linux/mm/hugetlb.c
Vishal Moola (Oracle) 98b74bb4d7 mm/hugetlb.c: fix UAF of vma in hugetlb fault pathway
Syzbot reports a UAF in hugetlb_fault().  This happens because
vmf_anon_prepare() could drop the per-VMA lock and allow the current VMA
to be freed before hugetlb_vma_unlock_read() is called.

We can fix this by using a modified version of vmf_anon_prepare() that
doesn't release the VMA lock on failure, and then release it ourselves
after hugetlb_vma_unlock_read().

Link: https://lkml.kernel.org/r/20240914194243.245-2-vishal.moola@gmail.com
Fixes: 9acad7ba3e ("hugetlb: use vmf_anon_prepare() instead of anon_vma_prepare()")
Reported-by: syzbot+2dab93857ee95f2eeb08@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-mm/00000000000067c20b06219fbc26@google.com/
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-17 00:58:04 -07:00

7838 lines
218 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Generic hugetlb support.
* (C) Nadia Yvette Chambers, April 2004
*/
#include <linux/list.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
#include <linux/mmu_notifier.h>
#include <linux/nodemask.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/compiler.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
#include <linux/memblock.h>
#include <linux/sysfs.h>
#include <linux/slab.h>
#include <linux/sched/mm.h>
#include <linux/mmdebug.h>
#include <linux/sched/signal.h>
#include <linux/rmap.h>
#include <linux/string_helpers.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/jhash.h>
#include <linux/numa.h>
#include <linux/llist.h>
#include <linux/cma.h>
#include <linux/migrate.h>
#include <linux/nospec.h>
#include <linux/delayacct.h>
#include <linux/memory.h>
#include <linux/mm_inline.h>
#include <linux/padata.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <linux/io.h>
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>
#include <linux/node.h>
#include <linux/page_owner.h>
#include "internal.h"
#include "hugetlb_vmemmap.h"
int hugetlb_max_hstate __read_mostly;
unsigned int default_hstate_idx;
struct hstate hstates[HUGE_MAX_HSTATE];
#ifdef CONFIG_CMA
static struct cma *hugetlb_cma[MAX_NUMNODES];
static unsigned long hugetlb_cma_size_in_node[MAX_NUMNODES] __initdata;
static bool hugetlb_cma_folio(struct folio *folio, unsigned int order)
{
return cma_pages_valid(hugetlb_cma[folio_nid(folio)], &folio->page,
1 << order);
}
#else
static bool hugetlb_cma_folio(struct folio *folio, unsigned int order)
{
return false;
}
#endif
static unsigned long hugetlb_cma_size __initdata;
__initdata struct list_head huge_boot_pages[MAX_NUMNODES];
/* for command line parsing */
static struct hstate * __initdata parsed_hstate;
static unsigned long __initdata default_hstate_max_huge_pages;
static bool __initdata parsed_valid_hugepagesz = true;
static bool __initdata parsed_default_hugepagesz;
static unsigned int default_hugepages_in_node[MAX_NUMNODES] __initdata;
/*
* Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
* free_huge_pages, and surplus_huge_pages.
*/
DEFINE_SPINLOCK(hugetlb_lock);
/*
* Serializes faults on the same logical page. This is used to
* prevent spurious OOMs when the hugepage pool is fully utilized.
*/
static int num_fault_mutexes;
struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
/* Forward declaration */
static int hugetlb_acct_memory(struct hstate *h, long delta);
static void hugetlb_vma_lock_free(struct vm_area_struct *vma);
static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma);
static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma);
static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
static struct resv_map *vma_resv_map(struct vm_area_struct *vma);
static inline bool subpool_is_free(struct hugepage_subpool *spool)
{
if (spool->count)
return false;
if (spool->max_hpages != -1)
return spool->used_hpages == 0;
if (spool->min_hpages != -1)
return spool->rsv_hpages == spool->min_hpages;
return true;
}
static inline void unlock_or_release_subpool(struct hugepage_subpool *spool,
unsigned long irq_flags)
{
spin_unlock_irqrestore(&spool->lock, irq_flags);
/* If no pages are used, and no other handles to the subpool
* remain, give up any reservations based on minimum size and
* free the subpool */
if (subpool_is_free(spool)) {
if (spool->min_hpages != -1)
hugetlb_acct_memory(spool->hstate,
-spool->min_hpages);
kfree(spool);
}
}
struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
long min_hpages)
{
struct hugepage_subpool *spool;
spool = kzalloc(sizeof(*spool), GFP_KERNEL);
if (!spool)
return NULL;
spin_lock_init(&spool->lock);
spool->count = 1;
spool->max_hpages = max_hpages;
spool->hstate = h;
spool->min_hpages = min_hpages;
if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
kfree(spool);
return NULL;
}
spool->rsv_hpages = min_hpages;
return spool;
}
void hugepage_put_subpool(struct hugepage_subpool *spool)
{
unsigned long flags;
spin_lock_irqsave(&spool->lock, flags);
BUG_ON(!spool->count);
spool->count--;
unlock_or_release_subpool(spool, flags);
}
/*
* Subpool accounting for allocating and reserving pages.
* Return -ENOMEM if there are not enough resources to satisfy the
* request. Otherwise, return the number of pages by which the
* global pools must be adjusted (upward). The returned value may
* only be different than the passed value (delta) in the case where
* a subpool minimum size must be maintained.
*/
static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
long delta)
{
long ret = delta;
if (!spool)
return ret;
spin_lock_irq(&spool->lock);
if (spool->max_hpages != -1) { /* maximum size accounting */
if ((spool->used_hpages + delta) <= spool->max_hpages)
spool->used_hpages += delta;
else {
ret = -ENOMEM;
goto unlock_ret;
}
}
/* minimum size accounting */
if (spool->min_hpages != -1 && spool->rsv_hpages) {
if (delta > spool->rsv_hpages) {
/*
* Asking for more reserves than those already taken on
* behalf of subpool. Return difference.
*/
ret = delta - spool->rsv_hpages;
spool->rsv_hpages = 0;
} else {
ret = 0; /* reserves already accounted for */
spool->rsv_hpages -= delta;
}
}
unlock_ret:
spin_unlock_irq(&spool->lock);
return ret;
}
/*
* Subpool accounting for freeing and unreserving pages.
* Return the number of global page reservations that must be dropped.
* The return value may only be different than the passed value (delta)
* in the case where a subpool minimum size must be maintained.
*/
static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
long delta)
{
long ret = delta;
unsigned long flags;
if (!spool)
return delta;
spin_lock_irqsave(&spool->lock, flags);
if (spool->max_hpages != -1) /* maximum size accounting */
spool->used_hpages -= delta;
/* minimum size accounting */
if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
if (spool->rsv_hpages + delta <= spool->min_hpages)
ret = 0;
else
ret = spool->rsv_hpages + delta - spool->min_hpages;
spool->rsv_hpages += delta;
if (spool->rsv_hpages > spool->min_hpages)
spool->rsv_hpages = spool->min_hpages;
}
/*
* If hugetlbfs_put_super couldn't free spool due to an outstanding
* quota reference, free it now.
*/
unlock_or_release_subpool(spool, flags);
return ret;
}
static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
{
return HUGETLBFS_SB(inode->i_sb)->spool;
}
static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
{
return subpool_inode(file_inode(vma->vm_file));
}
/*
* hugetlb vma_lock helper routines
*/
void hugetlb_vma_lock_read(struct vm_area_struct *vma)
{
if (__vma_shareable_lock(vma)) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
down_read(&vma_lock->rw_sema);
} else if (__vma_private_lock(vma)) {
struct resv_map *resv_map = vma_resv_map(vma);
down_read(&resv_map->rw_sema);
}
}
void hugetlb_vma_unlock_read(struct vm_area_struct *vma)
{
if (__vma_shareable_lock(vma)) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
up_read(&vma_lock->rw_sema);
} else if (__vma_private_lock(vma)) {
struct resv_map *resv_map = vma_resv_map(vma);
up_read(&resv_map->rw_sema);
}
}
void hugetlb_vma_lock_write(struct vm_area_struct *vma)
{
if (__vma_shareable_lock(vma)) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
down_write(&vma_lock->rw_sema);
} else if (__vma_private_lock(vma)) {
struct resv_map *resv_map = vma_resv_map(vma);
down_write(&resv_map->rw_sema);
}
}
void hugetlb_vma_unlock_write(struct vm_area_struct *vma)
{
if (__vma_shareable_lock(vma)) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
up_write(&vma_lock->rw_sema);
} else if (__vma_private_lock(vma)) {
struct resv_map *resv_map = vma_resv_map(vma);
up_write(&resv_map->rw_sema);
}
}
int hugetlb_vma_trylock_write(struct vm_area_struct *vma)
{
if (__vma_shareable_lock(vma)) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
return down_write_trylock(&vma_lock->rw_sema);
} else if (__vma_private_lock(vma)) {
struct resv_map *resv_map = vma_resv_map(vma);
return down_write_trylock(&resv_map->rw_sema);
}
return 1;
}
void hugetlb_vma_assert_locked(struct vm_area_struct *vma)
{
if (__vma_shareable_lock(vma)) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
lockdep_assert_held(&vma_lock->rw_sema);
} else if (__vma_private_lock(vma)) {
struct resv_map *resv_map = vma_resv_map(vma);
lockdep_assert_held(&resv_map->rw_sema);
}
}
void hugetlb_vma_lock_release(struct kref *kref)
{
struct hugetlb_vma_lock *vma_lock = container_of(kref,
struct hugetlb_vma_lock, refs);
kfree(vma_lock);
}
static void __hugetlb_vma_unlock_write_put(struct hugetlb_vma_lock *vma_lock)
{
struct vm_area_struct *vma = vma_lock->vma;
/*
* vma_lock structure may or not be released as a result of put,
* it certainly will no longer be attached to vma so clear pointer.
* Semaphore synchronizes access to vma_lock->vma field.
*/
vma_lock->vma = NULL;
vma->vm_private_data = NULL;
up_write(&vma_lock->rw_sema);
kref_put(&vma_lock->refs, hugetlb_vma_lock_release);
}
static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma)
{
if (__vma_shareable_lock(vma)) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
__hugetlb_vma_unlock_write_put(vma_lock);
} else if (__vma_private_lock(vma)) {
struct resv_map *resv_map = vma_resv_map(vma);
/* no free for anon vmas, but still need to unlock */
up_write(&resv_map->rw_sema);
}
}
static void hugetlb_vma_lock_free(struct vm_area_struct *vma)
{
/*
* Only present in sharable vmas.
*/
if (!vma || !__vma_shareable_lock(vma))
return;
if (vma->vm_private_data) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
down_write(&vma_lock->rw_sema);
__hugetlb_vma_unlock_write_put(vma_lock);
}
}
static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma)
{
struct hugetlb_vma_lock *vma_lock;
/* Only establish in (flags) sharable vmas */
if (!vma || !(vma->vm_flags & VM_MAYSHARE))
return;
/* Should never get here with non-NULL vm_private_data */
if (vma->vm_private_data)
return;
vma_lock = kmalloc(sizeof(*vma_lock), GFP_KERNEL);
if (!vma_lock) {
/*
* If we can not allocate structure, then vma can not
* participate in pmd sharing. This is only a possible
* performance enhancement and memory saving issue.
* However, the lock is also used to synchronize page
* faults with truncation. If the lock is not present,
* unlikely races could leave pages in a file past i_size
* until the file is removed. Warn in the unlikely case of
* allocation failure.
*/
pr_warn_once("HugeTLB: unable to allocate vma specific lock\n");
return;
}
kref_init(&vma_lock->refs);
init_rwsem(&vma_lock->rw_sema);
vma_lock->vma = vma;
vma->vm_private_data = vma_lock;
}
/* Helper that removes a struct file_region from the resv_map cache and returns
* it for use.
*/
static struct file_region *
get_file_region_entry_from_cache(struct resv_map *resv, long from, long to)
{
struct file_region *nrg;
VM_BUG_ON(resv->region_cache_count <= 0);
resv->region_cache_count--;
nrg = list_first_entry(&resv->region_cache, struct file_region, link);
list_del(&nrg->link);
nrg->from = from;
nrg->to = to;
return nrg;
}
static void copy_hugetlb_cgroup_uncharge_info(struct file_region *nrg,
struct file_region *rg)
{
#ifdef CONFIG_CGROUP_HUGETLB
nrg->reservation_counter = rg->reservation_counter;
nrg->css = rg->css;
if (rg->css)
css_get(rg->css);
#endif
}
/* Helper that records hugetlb_cgroup uncharge info. */
static void record_hugetlb_cgroup_uncharge_info(struct hugetlb_cgroup *h_cg,
struct hstate *h,
struct resv_map *resv,
struct file_region *nrg)
{
#ifdef CONFIG_CGROUP_HUGETLB
if (h_cg) {
nrg->reservation_counter =
&h_cg->rsvd_hugepage[hstate_index(h)];
nrg->css = &h_cg->css;
/*
* The caller will hold exactly one h_cg->css reference for the
* whole contiguous reservation region. But this area might be
* scattered when there are already some file_regions reside in
* it. As a result, many file_regions may share only one css
* reference. In order to ensure that one file_region must hold
* exactly one h_cg->css reference, we should do css_get for
* each file_region and leave the reference held by caller
* untouched.
*/
css_get(&h_cg->css);
if (!resv->pages_per_hpage)
resv->pages_per_hpage = pages_per_huge_page(h);
/* pages_per_hpage should be the same for all entries in
* a resv_map.
*/
VM_BUG_ON(resv->pages_per_hpage != pages_per_huge_page(h));
} else {
nrg->reservation_counter = NULL;
nrg->css = NULL;
}
#endif
}
static void put_uncharge_info(struct file_region *rg)
{
#ifdef CONFIG_CGROUP_HUGETLB
if (rg->css)
css_put(rg->css);
#endif
}
static bool has_same_uncharge_info(struct file_region *rg,
struct file_region *org)
{
#ifdef CONFIG_CGROUP_HUGETLB
return rg->reservation_counter == org->reservation_counter &&
rg->css == org->css;
#else
return true;
#endif
}
static void coalesce_file_region(struct resv_map *resv, struct file_region *rg)
{
struct file_region *nrg, *prg;
prg = list_prev_entry(rg, link);
if (&prg->link != &resv->regions && prg->to == rg->from &&
has_same_uncharge_info(prg, rg)) {
prg->to = rg->to;
list_del(&rg->link);
put_uncharge_info(rg);
kfree(rg);
rg = prg;
}
nrg = list_next_entry(rg, link);
if (&nrg->link != &resv->regions && nrg->from == rg->to &&
has_same_uncharge_info(nrg, rg)) {
nrg->from = rg->from;
list_del(&rg->link);
put_uncharge_info(rg);
kfree(rg);
}
}
static inline long
hugetlb_resv_map_add(struct resv_map *map, struct list_head *rg, long from,
long to, struct hstate *h, struct hugetlb_cgroup *cg,
long *regions_needed)
{
struct file_region *nrg;
if (!regions_needed) {
nrg = get_file_region_entry_from_cache(map, from, to);
record_hugetlb_cgroup_uncharge_info(cg, h, map, nrg);
list_add(&nrg->link, rg);
coalesce_file_region(map, nrg);
} else
*regions_needed += 1;
return to - from;
}
/*
* Must be called with resv->lock held.
*
* Calling this with regions_needed != NULL will count the number of pages
* to be added but will not modify the linked list. And regions_needed will
* indicate the number of file_regions needed in the cache to carry out to add
* the regions for this range.
*/
static long add_reservation_in_range(struct resv_map *resv, long f, long t,
struct hugetlb_cgroup *h_cg,
struct hstate *h, long *regions_needed)
{
long add = 0;
struct list_head *head = &resv->regions;
long last_accounted_offset = f;
struct file_region *iter, *trg = NULL;
struct list_head *rg = NULL;
if (regions_needed)
*regions_needed = 0;
/* In this loop, we essentially handle an entry for the range
* [last_accounted_offset, iter->from), at every iteration, with some
* bounds checking.
*/
list_for_each_entry_safe(iter, trg, head, link) {
/* Skip irrelevant regions that start before our range. */
if (iter->from < f) {
/* If this region ends after the last accounted offset,
* then we need to update last_accounted_offset.
*/
if (iter->to > last_accounted_offset)
last_accounted_offset = iter->to;
continue;
}
/* When we find a region that starts beyond our range, we've
* finished.
*/
if (iter->from >= t) {
rg = iter->link.prev;
break;
}
/* Add an entry for last_accounted_offset -> iter->from, and
* update last_accounted_offset.
*/
if (iter->from > last_accounted_offset)
add += hugetlb_resv_map_add(resv, iter->link.prev,
last_accounted_offset,
iter->from, h, h_cg,
regions_needed);
last_accounted_offset = iter->to;
}
/* Handle the case where our range extends beyond
* last_accounted_offset.
*/
if (!rg)
rg = head->prev;
if (last_accounted_offset < t)
add += hugetlb_resv_map_add(resv, rg, last_accounted_offset,
t, h, h_cg, regions_needed);
return add;
}
/* Must be called with resv->lock acquired. Will drop lock to allocate entries.
*/
static int allocate_file_region_entries(struct resv_map *resv,
int regions_needed)
__must_hold(&resv->lock)
{
LIST_HEAD(allocated_regions);
int to_allocate = 0, i = 0;
struct file_region *trg = NULL, *rg = NULL;
VM_BUG_ON(regions_needed < 0);
/*
* Check for sufficient descriptors in the cache to accommodate
* the number of in progress add operations plus regions_needed.
*
* This is a while loop because when we drop the lock, some other call
* to region_add or region_del may have consumed some region_entries,
* so we keep looping here until we finally have enough entries for
* (adds_in_progress + regions_needed).
*/
while (resv->region_cache_count <
(resv->adds_in_progress + regions_needed)) {
to_allocate = resv->adds_in_progress + regions_needed -
resv->region_cache_count;
/* At this point, we should have enough entries in the cache
* for all the existing adds_in_progress. We should only be
* needing to allocate for regions_needed.
*/
VM_BUG_ON(resv->region_cache_count < resv->adds_in_progress);
spin_unlock(&resv->lock);
for (i = 0; i < to_allocate; i++) {
trg = kmalloc(sizeof(*trg), GFP_KERNEL);
if (!trg)
goto out_of_memory;
list_add(&trg->link, &allocated_regions);
}
spin_lock(&resv->lock);
list_splice(&allocated_regions, &resv->region_cache);
resv->region_cache_count += to_allocate;
}
return 0;
out_of_memory:
list_for_each_entry_safe(rg, trg, &allocated_regions, link) {
list_del(&rg->link);
kfree(rg);
}
return -ENOMEM;
}
/*
* Add the huge page range represented by [f, t) to the reserve
* map. Regions will be taken from the cache to fill in this range.
* Sufficient regions should exist in the cache due to the previous
* call to region_chg with the same range, but in some cases the cache will not
* have sufficient entries due to races with other code doing region_add or
* region_del. The extra needed entries will be allocated.
*
* regions_needed is the out value provided by a previous call to region_chg.
*
* Return the number of new huge pages added to the map. This number is greater
* than or equal to zero. If file_region entries needed to be allocated for
* this operation and we were not able to allocate, it returns -ENOMEM.
* region_add of regions of length 1 never allocate file_regions and cannot
* fail; region_chg will always allocate at least 1 entry and a region_add for
* 1 page will only require at most 1 entry.
*/
static long region_add(struct resv_map *resv, long f, long t,
long in_regions_needed, struct hstate *h,
struct hugetlb_cgroup *h_cg)
{
long add = 0, actual_regions_needed = 0;
spin_lock(&resv->lock);
retry:
/* Count how many regions are actually needed to execute this add. */
add_reservation_in_range(resv, f, t, NULL, NULL,
&actual_regions_needed);
/*
* Check for sufficient descriptors in the cache to accommodate
* this add operation. Note that actual_regions_needed may be greater
* than in_regions_needed, as the resv_map may have been modified since
* the region_chg call. In this case, we need to make sure that we
* allocate extra entries, such that we have enough for all the
* existing adds_in_progress, plus the excess needed for this
* operation.
*/
if (actual_regions_needed > in_regions_needed &&
resv->region_cache_count <
resv->adds_in_progress +
(actual_regions_needed - in_regions_needed)) {
/* region_add operation of range 1 should never need to
* allocate file_region entries.
*/
VM_BUG_ON(t - f <= 1);
if (allocate_file_region_entries(
resv, actual_regions_needed - in_regions_needed)) {
return -ENOMEM;
}
goto retry;
}
add = add_reservation_in_range(resv, f, t, h_cg, h, NULL);
resv->adds_in_progress -= in_regions_needed;
spin_unlock(&resv->lock);
return add;
}
/*
* Examine the existing reserve map and determine how many
* huge pages in the specified range [f, t) are NOT currently
* represented. This routine is called before a subsequent
* call to region_add that will actually modify the reserve
* map to add the specified range [f, t). region_chg does
* not change the number of huge pages represented by the
* map. A number of new file_region structures is added to the cache as a
* placeholder, for the subsequent region_add call to use. At least 1
* file_region structure is added.
*
* out_regions_needed is the number of regions added to the
* resv->adds_in_progress. This value needs to be provided to a follow up call
* to region_add or region_abort for proper accounting.
*
* Returns the number of huge pages that need to be added to the existing
* reservation map for the range [f, t). This number is greater or equal to
* zero. -ENOMEM is returned if a new file_region structure or cache entry
* is needed and can not be allocated.
*/
static long region_chg(struct resv_map *resv, long f, long t,
long *out_regions_needed)
{
long chg = 0;
spin_lock(&resv->lock);
/* Count how many hugepages in this range are NOT represented. */
chg = add_reservation_in_range(resv, f, t, NULL, NULL,
out_regions_needed);
if (*out_regions_needed == 0)
*out_regions_needed = 1;
if (allocate_file_region_entries(resv, *out_regions_needed))
return -ENOMEM;
resv->adds_in_progress += *out_regions_needed;
spin_unlock(&resv->lock);
return chg;
}
/*
* Abort the in progress add operation. The adds_in_progress field
* of the resv_map keeps track of the operations in progress between
* calls to region_chg and region_add. Operations are sometimes
* aborted after the call to region_chg. In such cases, region_abort
* is called to decrement the adds_in_progress counter. regions_needed
* is the value returned by the region_chg call, it is used to decrement
* the adds_in_progress counter.
*
* NOTE: The range arguments [f, t) are not needed or used in this
* routine. They are kept to make reading the calling code easier as
* arguments will match the associated region_chg call.
*/
static void region_abort(struct resv_map *resv, long f, long t,
long regions_needed)
{
spin_lock(&resv->lock);
VM_BUG_ON(!resv->region_cache_count);
resv->adds_in_progress -= regions_needed;
spin_unlock(&resv->lock);
}
/*
* Delete the specified range [f, t) from the reserve map. If the
* t parameter is LONG_MAX, this indicates that ALL regions after f
* should be deleted. Locate the regions which intersect [f, t)
* and either trim, delete or split the existing regions.
*
* Returns the number of huge pages deleted from the reserve map.
* In the normal case, the return value is zero or more. In the
* case where a region must be split, a new region descriptor must
* be allocated. If the allocation fails, -ENOMEM will be returned.
* NOTE: If the parameter t == LONG_MAX, then we will never split
* a region and possibly return -ENOMEM. Callers specifying
* t == LONG_MAX do not need to check for -ENOMEM error.
*/
static long region_del(struct resv_map *resv, long f, long t)
{
struct list_head *head = &resv->regions;
struct file_region *rg, *trg;
struct file_region *nrg = NULL;
long del = 0;
retry:
spin_lock(&resv->lock);
list_for_each_entry_safe(rg, trg, head, link) {
/*
* Skip regions before the range to be deleted. file_region
* ranges are normally of the form [from, to). However, there
* may be a "placeholder" entry in the map which is of the form
* (from, to) with from == to. Check for placeholder entries
* at the beginning of the range to be deleted.
*/
if (rg->to <= f && (rg->to != rg->from || rg->to != f))
continue;
if (rg->from >= t)
break;
if (f > rg->from && t < rg->to) { /* Must split region */
/*
* Check for an entry in the cache before dropping
* lock and attempting allocation.
*/
if (!nrg &&
resv->region_cache_count > resv->adds_in_progress) {
nrg = list_first_entry(&resv->region_cache,
struct file_region,
link);
list_del(&nrg->link);
resv->region_cache_count--;
}
if (!nrg) {
spin_unlock(&resv->lock);
nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
if (!nrg)
return -ENOMEM;
goto retry;
}
del += t - f;
hugetlb_cgroup_uncharge_file_region(
resv, rg, t - f, false);
/* New entry for end of split region */
nrg->from = t;
nrg->to = rg->to;
copy_hugetlb_cgroup_uncharge_info(nrg, rg);
INIT_LIST_HEAD(&nrg->link);
/* Original entry is trimmed */
rg->to = f;
list_add(&nrg->link, &rg->link);
nrg = NULL;
break;
}
if (f <= rg->from && t >= rg->to) { /* Remove entire region */
del += rg->to - rg->from;
hugetlb_cgroup_uncharge_file_region(resv, rg,
rg->to - rg->from, true);
list_del(&rg->link);
kfree(rg);
continue;
}
if (f <= rg->from) { /* Trim beginning of region */
hugetlb_cgroup_uncharge_file_region(resv, rg,
t - rg->from, false);
del += t - rg->from;
rg->from = t;
} else { /* Trim end of region */
hugetlb_cgroup_uncharge_file_region(resv, rg,
rg->to - f, false);
del += rg->to - f;
rg->to = f;
}
}
spin_unlock(&resv->lock);
kfree(nrg);
return del;
}
/*
* A rare out of memory error was encountered which prevented removal of
* the reserve map region for a page. The huge page itself was free'ed
* and removed from the page cache. This routine will adjust the subpool
* usage count, and the global reserve count if needed. By incrementing
* these counts, the reserve map entry which could not be deleted will
* appear as a "reserved" entry instead of simply dangling with incorrect
* counts.
*/
void hugetlb_fix_reserve_counts(struct inode *inode)
{
struct hugepage_subpool *spool = subpool_inode(inode);
long rsv_adjust;
bool reserved = false;
rsv_adjust = hugepage_subpool_get_pages(spool, 1);
if (rsv_adjust > 0) {
struct hstate *h = hstate_inode(inode);
if (!hugetlb_acct_memory(h, 1))
reserved = true;
} else if (!rsv_adjust) {
reserved = true;
}
if (!reserved)
pr_warn("hugetlb: Huge Page Reserved count may go negative.\n");
}
/*
* Count and return the number of huge pages in the reserve map
* that intersect with the range [f, t).
*/
static long region_count(struct resv_map *resv, long f, long t)
{
struct list_head *head = &resv->regions;
struct file_region *rg;
long chg = 0;
spin_lock(&resv->lock);
/* Locate each segment we overlap with, and count that overlap. */
list_for_each_entry(rg, head, link) {
long seg_from;
long seg_to;
if (rg->to <= f)
continue;
if (rg->from >= t)
break;
seg_from = max(rg->from, f);
seg_to = min(rg->to, t);
chg += seg_to - seg_from;
}
spin_unlock(&resv->lock);
return chg;
}
/*
* Convert the address within this vma to the page offset within
* the mapping, huge page units here.
*/
static pgoff_t vma_hugecache_offset(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
return ((address - vma->vm_start) >> huge_page_shift(h)) +
(vma->vm_pgoff >> huge_page_order(h));
}
/**
* vma_kernel_pagesize - Page size granularity for this VMA.
* @vma: The user mapping.
*
* Folios in this VMA will be aligned to, and at least the size of the
* number of bytes returned by this function.
*
* Return: The default size of the folios allocated when backing a VMA.
*/
unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
{
if (vma->vm_ops && vma->vm_ops->pagesize)
return vma->vm_ops->pagesize(vma);
return PAGE_SIZE;
}
EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
/*
* Return the page size being used by the MMU to back a VMA. In the majority
* of cases, the page size used by the kernel matches the MMU size. On
* architectures where it differs, an architecture-specific 'strong'
* version of this symbol is required.
*/
__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
return vma_kernel_pagesize(vma);
}
/*
* Flags for MAP_PRIVATE reservations. These are stored in the bottom
* bits of the reservation map pointer, which are always clear due to
* alignment.
*/
#define HPAGE_RESV_OWNER (1UL << 0)
#define HPAGE_RESV_UNMAPPED (1UL << 1)
#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
/*
* These helpers are used to track how many pages are reserved for
* faults in a MAP_PRIVATE mapping. Only the process that called mmap()
* is guaranteed to have their future faults succeed.
*
* With the exception of hugetlb_dup_vma_private() which is called at fork(),
* the reserve counters are updated with the hugetlb_lock held. It is safe
* to reset the VMA at fork() time as it is not in use yet and there is no
* chance of the global counters getting corrupted as a result of the values.
*
* The private mapping reservation is represented in a subtly different
* manner to a shared mapping. A shared mapping has a region map associated
* with the underlying file, this region map represents the backing file
* pages which have ever had a reservation assigned which this persists even
* after the page is instantiated. A private mapping has a region map
* associated with the original mmap which is attached to all VMAs which
* reference it, this region map represents those offsets which have consumed
* reservation ie. where pages have been instantiated.
*/
static unsigned long get_vma_private_data(struct vm_area_struct *vma)
{
return (unsigned long)vma->vm_private_data;
}
static void set_vma_private_data(struct vm_area_struct *vma,
unsigned long value)
{
vma->vm_private_data = (void *)value;
}
static void
resv_map_set_hugetlb_cgroup_uncharge_info(struct resv_map *resv_map,
struct hugetlb_cgroup *h_cg,
struct hstate *h)
{
#ifdef CONFIG_CGROUP_HUGETLB
if (!h_cg || !h) {
resv_map->reservation_counter = NULL;
resv_map->pages_per_hpage = 0;
resv_map->css = NULL;
} else {
resv_map->reservation_counter =
&h_cg->rsvd_hugepage[hstate_index(h)];
resv_map->pages_per_hpage = pages_per_huge_page(h);
resv_map->css = &h_cg->css;
}
#endif
}
struct resv_map *resv_map_alloc(void)
{
struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
if (!resv_map || !rg) {
kfree(resv_map);
kfree(rg);
return NULL;
}
kref_init(&resv_map->refs);
spin_lock_init(&resv_map->lock);
INIT_LIST_HEAD(&resv_map->regions);
init_rwsem(&resv_map->rw_sema);
resv_map->adds_in_progress = 0;
/*
* Initialize these to 0. On shared mappings, 0's here indicate these
* fields don't do cgroup accounting. On private mappings, these will be
* re-initialized to the proper values, to indicate that hugetlb cgroup
* reservations are to be un-charged from here.
*/
resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, NULL, NULL);
INIT_LIST_HEAD(&resv_map->region_cache);
list_add(&rg->link, &resv_map->region_cache);
resv_map->region_cache_count = 1;
return resv_map;
}
void resv_map_release(struct kref *ref)
{
struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
struct list_head *head = &resv_map->region_cache;
struct file_region *rg, *trg;
/* Clear out any active regions before we release the map. */
region_del(resv_map, 0, LONG_MAX);
/* ... and any entries left in the cache */
list_for_each_entry_safe(rg, trg, head, link) {
list_del(&rg->link);
kfree(rg);
}
VM_BUG_ON(resv_map->adds_in_progress);
kfree(resv_map);
}
static inline struct resv_map *inode_resv_map(struct inode *inode)
{
/*
* At inode evict time, i_mapping may not point to the original
* address space within the inode. This original address space
* contains the pointer to the resv_map. So, always use the
* address space embedded within the inode.
* The VERY common case is inode->mapping == &inode->i_data but,
* this may not be true for device special inodes.
*/
return (struct resv_map *)(&inode->i_data)->i_private_data;
}
static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
if (vma->vm_flags & VM_MAYSHARE) {
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
return inode_resv_map(inode);
} else {
return (struct resv_map *)(get_vma_private_data(vma) &
~HPAGE_RESV_MASK);
}
}
static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
set_vma_private_data(vma, (unsigned long)map);
}
static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
set_vma_private_data(vma, get_vma_private_data(vma) | flags);
}
static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
return (get_vma_private_data(vma) & flag) != 0;
}
bool __vma_private_lock(struct vm_area_struct *vma)
{
return !(vma->vm_flags & VM_MAYSHARE) &&
get_vma_private_data(vma) & ~HPAGE_RESV_MASK &&
is_vma_resv_set(vma, HPAGE_RESV_OWNER);
}
void hugetlb_dup_vma_private(struct vm_area_struct *vma)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
/*
* Clear vm_private_data
* - For shared mappings this is a per-vma semaphore that may be
* allocated in a subsequent call to hugetlb_vm_op_open.
* Before clearing, make sure pointer is not associated with vma
* as this will leak the structure. This is the case when called
* via clear_vma_resv_huge_pages() and hugetlb_vm_op_open has already
* been called to allocate a new structure.
* - For MAP_PRIVATE mappings, this is the reserve map which does
* not apply to children. Faults generated by the children are
* not guaranteed to succeed, even if read-only.
*/
if (vma->vm_flags & VM_MAYSHARE) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
if (vma_lock && vma_lock->vma != vma)
vma->vm_private_data = NULL;
} else
vma->vm_private_data = NULL;
}
/*
* Reset and decrement one ref on hugepage private reservation.
* Called with mm->mmap_lock writer semaphore held.
* This function should be only used by move_vma() and operate on
* same sized vma. It should never come here with last ref on the
* reservation.
*/
void clear_vma_resv_huge_pages(struct vm_area_struct *vma)
{
/*
* Clear the old hugetlb private page reservation.
* It has already been transferred to new_vma.
*
* During a mremap() operation of a hugetlb vma we call move_vma()
* which copies vma into new_vma and unmaps vma. After the copy
* operation both new_vma and vma share a reference to the resv_map
* struct, and at that point vma is about to be unmapped. We don't
* want to return the reservation to the pool at unmap of vma because
* the reservation still lives on in new_vma, so simply decrement the
* ref here and remove the resv_map reference from this vma.
*/
struct resv_map *reservations = vma_resv_map(vma);
if (reservations && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
resv_map_put_hugetlb_cgroup_uncharge_info(reservations);
kref_put(&reservations->refs, resv_map_release);
}
hugetlb_dup_vma_private(vma);
}
/* Returns true if the VMA has associated reserve pages */
static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
{
if (vma->vm_flags & VM_NORESERVE) {
/*
* This address is already reserved by other process(chg == 0),
* so, we should decrement reserved count. Without decrementing,
* reserve count remains after releasing inode, because this
* allocated page will go into page cache and is regarded as
* coming from reserved pool in releasing step. Currently, we
* don't have any other solution to deal with this situation
* properly, so add work-around here.
*/
if (vma->vm_flags & VM_MAYSHARE && chg == 0)
return true;
else
return false;
}
/* Shared mappings always use reserves */
if (vma->vm_flags & VM_MAYSHARE) {
/*
* We know VM_NORESERVE is not set. Therefore, there SHOULD
* be a region map for all pages. The only situation where
* there is no region map is if a hole was punched via
* fallocate. In this case, there really are no reserves to
* use. This situation is indicated if chg != 0.
*/
if (chg)
return false;
else
return true;
}
/*
* Only the process that called mmap() has reserves for
* private mappings.
*/
if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
/*
* Like the shared case above, a hole punch or truncate
* could have been performed on the private mapping.
* Examine the value of chg to determine if reserves
* actually exist or were previously consumed.
* Very Subtle - The value of chg comes from a previous
* call to vma_needs_reserves(). The reserve map for
* private mappings has different (opposite) semantics
* than that of shared mappings. vma_needs_reserves()
* has already taken this difference in semantics into
* account. Therefore, the meaning of chg is the same
* as in the shared case above. Code could easily be
* combined, but keeping it separate draws attention to
* subtle differences.
*/
if (chg)
return false;
else
return true;
}
return false;
}
static void enqueue_hugetlb_folio(struct hstate *h, struct folio *folio)
{
int nid = folio_nid(folio);
lockdep_assert_held(&hugetlb_lock);
VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);
list_move(&folio->lru, &h->hugepage_freelists[nid]);
h->free_huge_pages++;
h->free_huge_pages_node[nid]++;
folio_set_hugetlb_freed(folio);
}
static struct folio *dequeue_hugetlb_folio_node_exact(struct hstate *h,
int nid)
{
struct folio *folio;
bool pin = !!(current->flags & PF_MEMALLOC_PIN);
lockdep_assert_held(&hugetlb_lock);
list_for_each_entry(folio, &h->hugepage_freelists[nid], lru) {
if (pin && !folio_is_longterm_pinnable(folio))
continue;
if (folio_test_hwpoison(folio))
continue;
list_move(&folio->lru, &h->hugepage_activelist);
folio_ref_unfreeze(folio, 1);
folio_clear_hugetlb_freed(folio);
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
return folio;
}
return NULL;
}
static struct folio *dequeue_hugetlb_folio_nodemask(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nmask)
{
unsigned int cpuset_mems_cookie;
struct zonelist *zonelist;
struct zone *zone;
struct zoneref *z;
int node = NUMA_NO_NODE;
/* 'nid' should not be NUMA_NO_NODE. Try to catch any misuse of it and rectifiy. */
if (nid == NUMA_NO_NODE)
nid = numa_node_id();
zonelist = node_zonelist(nid, gfp_mask);
retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();
for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nmask) {
struct folio *folio;
if (!cpuset_zone_allowed(zone, gfp_mask))
continue;
/*
* no need to ask again on the same node. Pool is node rather than
* zone aware
*/
if (zone_to_nid(zone) == node)
continue;
node = zone_to_nid(zone);
folio = dequeue_hugetlb_folio_node_exact(h, node);
if (folio)
return folio;
}
if (unlikely(read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
return NULL;
}
static unsigned long available_huge_pages(struct hstate *h)
{
return h->free_huge_pages - h->resv_huge_pages;
}
static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
struct vm_area_struct *vma,
unsigned long address, int avoid_reserve,
long chg)
{
struct folio *folio = NULL;
struct mempolicy *mpol;
gfp_t gfp_mask;
nodemask_t *nodemask;
int nid;
/*
* A child process with MAP_PRIVATE mappings created by their parent
* have no page reserves. This check ensures that reservations are
* not "stolen". The child may still get SIGKILLed
*/
if (!vma_has_reserves(vma, chg) && !available_huge_pages(h))
goto err;
/* If reserves cannot be used, ensure enough pages are in the pool */
if (avoid_reserve && !available_huge_pages(h))
goto err;
gfp_mask = htlb_alloc_mask(h);
nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
if (mpol_is_preferred_many(mpol)) {
folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask,
nid, nodemask);
/* Fallback to all nodes if page==NULL */
nodemask = NULL;
}
if (!folio)
folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask,
nid, nodemask);
if (folio && !avoid_reserve && vma_has_reserves(vma, chg)) {
folio_set_hugetlb_restore_reserve(folio);
h->resv_huge_pages--;
}
mpol_cond_put(mpol);
return folio;
err:
return NULL;
}
/*
* common helper functions for hstate_next_node_to_{alloc|free}.
* We may have allocated or freed a huge page based on a different
* nodes_allowed previously, so h->next_node_to_{alloc|free} might
* be outside of *nodes_allowed. Ensure that we use an allowed
* node for alloc or free.
*/
static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
{
nid = next_node_in(nid, *nodes_allowed);
VM_BUG_ON(nid >= MAX_NUMNODES);
return nid;
}
static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
{
if (!node_isset(nid, *nodes_allowed))
nid = next_node_allowed(nid, nodes_allowed);
return nid;
}
/*
* returns the previously saved node ["this node"] from which to
* allocate a persistent huge page for the pool and advance the
* next node from which to allocate, handling wrap at end of node
* mask.
*/
static int hstate_next_node_to_alloc(int *next_node,
nodemask_t *nodes_allowed)
{
int nid;
VM_BUG_ON(!nodes_allowed);
nid = get_valid_node_allowed(*next_node, nodes_allowed);
*next_node = next_node_allowed(nid, nodes_allowed);
return nid;
}
/*
* helper for remove_pool_hugetlb_folio() - return the previously saved
* node ["this node"] from which to free a huge page. Advance the
* next node id whether or not we find a free huge page to free so
* that the next attempt to free addresses the next node.
*/
static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
{
int nid;
VM_BUG_ON(!nodes_allowed);
nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
return nid;
}
#define for_each_node_mask_to_alloc(next_node, nr_nodes, node, mask) \
for (nr_nodes = nodes_weight(*mask); \
nr_nodes > 0 && \
((node = hstate_next_node_to_alloc(next_node, mask)) || 1); \
nr_nodes--)
#define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \
for (nr_nodes = nodes_weight(*mask); \
nr_nodes > 0 && \
((node = hstate_next_node_to_free(hs, mask)) || 1); \
nr_nodes--)
/* used to demote non-gigantic_huge pages as well */
static void __destroy_compound_gigantic_folio(struct folio *folio,
unsigned int order, bool demote)
{
int i;
int nr_pages = 1 << order;
struct page *p;
atomic_set(&folio->_entire_mapcount, 0);
atomic_set(&folio->_large_mapcount, 0);
atomic_set(&folio->_pincount, 0);
for (i = 1; i < nr_pages; i++) {
p = folio_page(folio, i);
p->flags &= ~PAGE_FLAGS_CHECK_AT_FREE;
p->mapping = NULL;
clear_compound_head(p);
if (!demote)
set_page_refcounted(p);
}
__folio_clear_head(folio);
}
static void destroy_compound_hugetlb_folio_for_demote(struct folio *folio,
unsigned int order)
{
__destroy_compound_gigantic_folio(folio, order, true);
}
#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
static void destroy_compound_gigantic_folio(struct folio *folio,
unsigned int order)
{
__destroy_compound_gigantic_folio(folio, order, false);
}
static void free_gigantic_folio(struct folio *folio, unsigned int order)
{
/*
* If the page isn't allocated using the cma allocator,
* cma_release() returns false.
*/
#ifdef CONFIG_CMA
int nid = folio_nid(folio);
if (cma_release(hugetlb_cma[nid], &folio->page, 1 << order))
return;
#endif
free_contig_range(folio_pfn(folio), 1 << order);
}
#ifdef CONFIG_CONTIG_ALLOC
static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nodemask)
{
struct page *page;
unsigned long nr_pages = pages_per_huge_page(h);
if (nid == NUMA_NO_NODE)
nid = numa_mem_id();
#ifdef CONFIG_CMA
{
int node;
if (hugetlb_cma[nid]) {
page = cma_alloc(hugetlb_cma[nid], nr_pages,
huge_page_order(h), true);
if (page)
return page_folio(page);
}
if (!(gfp_mask & __GFP_THISNODE)) {
for_each_node_mask(node, *nodemask) {
if (node == nid || !hugetlb_cma[node])
continue;
page = cma_alloc(hugetlb_cma[node], nr_pages,
huge_page_order(h), true);
if (page)
return page_folio(page);
}
}
}
#endif
page = alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask);
return page ? page_folio(page) : NULL;
}
#else /* !CONFIG_CONTIG_ALLOC */
static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nodemask)
{
return NULL;
}
#endif /* CONFIG_CONTIG_ALLOC */
#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nodemask)
{
return NULL;
}
static inline void free_gigantic_folio(struct folio *folio,
unsigned int order) { }
static inline void destroy_compound_gigantic_folio(struct folio *folio,
unsigned int order) { }
#endif
/*
* Remove hugetlb folio from lists.
* If vmemmap exists for the folio, clear the hugetlb flag so that the
* folio appears as just a compound page. Otherwise, wait until after
* allocating vmemmap to clear the flag.
*
* Must be called with hugetlb lock held.
*/
static void remove_hugetlb_folio(struct hstate *h, struct folio *folio,
bool adjust_surplus)
{
int nid = folio_nid(folio);
VM_BUG_ON_FOLIO(hugetlb_cgroup_from_folio(folio), folio);
VM_BUG_ON_FOLIO(hugetlb_cgroup_from_folio_rsvd(folio), folio);
lockdep_assert_held(&hugetlb_lock);
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
return;
list_del(&folio->lru);
if (folio_test_hugetlb_freed(folio)) {
folio_clear_hugetlb_freed(folio);
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
}
if (adjust_surplus) {
h->surplus_huge_pages--;
h->surplus_huge_pages_node[nid]--;
}
/*
* We can only clear the hugetlb flag after allocating vmemmap
* pages. Otherwise, someone (memory error handling) may try to write
* to tail struct pages.
*/
if (!folio_test_hugetlb_vmemmap_optimized(folio))
__folio_clear_hugetlb(folio);
h->nr_huge_pages--;
h->nr_huge_pages_node[nid]--;
}
static void add_hugetlb_folio(struct hstate *h, struct folio *folio,
bool adjust_surplus)
{
int nid = folio_nid(folio);
VM_BUG_ON_FOLIO(!folio_test_hugetlb_vmemmap_optimized(folio), folio);
lockdep_assert_held(&hugetlb_lock);
INIT_LIST_HEAD(&folio->lru);
h->nr_huge_pages++;
h->nr_huge_pages_node[nid]++;
if (adjust_surplus) {
h->surplus_huge_pages++;
h->surplus_huge_pages_node[nid]++;
}
__folio_set_hugetlb(folio);
folio_change_private(folio, NULL);
/*
* We have to set hugetlb_vmemmap_optimized again as above
* folio_change_private(folio, NULL) cleared it.
*/
folio_set_hugetlb_vmemmap_optimized(folio);
arch_clear_hugetlb_flags(folio);
enqueue_hugetlb_folio(h, folio);
}
static void __update_and_free_hugetlb_folio(struct hstate *h,
struct folio *folio)
{
bool clear_flag = folio_test_hugetlb_vmemmap_optimized(folio);
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
return;
/*
* If we don't know which subpages are hwpoisoned, we can't free
* the hugepage, so it's leaked intentionally.
*/
if (folio_test_hugetlb_raw_hwp_unreliable(folio))
return;
/*
* If folio is not vmemmap optimized (!clear_flag), then the folio
* is no longer identified as a hugetlb page. hugetlb_vmemmap_restore_folio
* can only be passed hugetlb pages and will BUG otherwise.
*/
if (clear_flag && hugetlb_vmemmap_restore_folio(h, folio)) {
spin_lock_irq(&hugetlb_lock);
/*
* If we cannot allocate vmemmap pages, just refuse to free the
* page and put the page back on the hugetlb free list and treat
* as a surplus page.
*/
add_hugetlb_folio(h, folio, true);
spin_unlock_irq(&hugetlb_lock);
return;
}
/*
* If vmemmap pages were allocated above, then we need to clear the
* hugetlb flag under the hugetlb lock.
*/
if (folio_test_hugetlb(folio)) {
spin_lock_irq(&hugetlb_lock);
__folio_clear_hugetlb(folio);
spin_unlock_irq(&hugetlb_lock);
}
/*
* Move PageHWPoison flag from head page to the raw error pages,
* which makes any healthy subpages reusable.
*/
if (unlikely(folio_test_hwpoison(folio)))
folio_clear_hugetlb_hwpoison(folio);
folio_ref_unfreeze(folio, 1);
/*
* Non-gigantic pages demoted from CMA allocated gigantic pages
* need to be given back to CMA in free_gigantic_folio.
*/
if (hstate_is_gigantic(h) ||
hugetlb_cma_folio(folio, huge_page_order(h))) {
destroy_compound_gigantic_folio(folio, huge_page_order(h));
free_gigantic_folio(folio, huge_page_order(h));
} else {
INIT_LIST_HEAD(&folio->_deferred_list);
folio_put(folio);
}
}
/*
* As update_and_free_hugetlb_folio() can be called under any context, so we cannot
* use GFP_KERNEL to allocate vmemmap pages. However, we can defer the
* actual freeing in a workqueue to prevent from using GFP_ATOMIC to allocate
* the vmemmap pages.
*
* free_hpage_workfn() locklessly retrieves the linked list of pages to be
* freed and frees them one-by-one. As the page->mapping pointer is going
* to be cleared in free_hpage_workfn() anyway, it is reused as the llist_node
* structure of a lockless linked list of huge pages to be freed.
*/
static LLIST_HEAD(hpage_freelist);
static void free_hpage_workfn(struct work_struct *work)
{
struct llist_node *node;
node = llist_del_all(&hpage_freelist);
while (node) {
struct folio *folio;
struct hstate *h;
folio = container_of((struct address_space **)node,
struct folio, mapping);
node = node->next;
folio->mapping = NULL;
/*
* The VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio) in
* folio_hstate() is going to trigger because a previous call to
* remove_hugetlb_folio() will clear the hugetlb bit, so do
* not use folio_hstate() directly.
*/
h = size_to_hstate(folio_size(folio));
__update_and_free_hugetlb_folio(h, folio);
cond_resched();
}
}
static DECLARE_WORK(free_hpage_work, free_hpage_workfn);
static inline void flush_free_hpage_work(struct hstate *h)
{
if (hugetlb_vmemmap_optimizable(h))
flush_work(&free_hpage_work);
}
static void update_and_free_hugetlb_folio(struct hstate *h, struct folio *folio,
bool atomic)
{
if (!folio_test_hugetlb_vmemmap_optimized(folio) || !atomic) {
__update_and_free_hugetlb_folio(h, folio);
return;
}
/*
* Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap pages.
*
* Only call schedule_work() if hpage_freelist is previously
* empty. Otherwise, schedule_work() had been called but the workfn
* hasn't retrieved the list yet.
*/
if (llist_add((struct llist_node *)&folio->mapping, &hpage_freelist))
schedule_work(&free_hpage_work);
}
static void bulk_vmemmap_restore_error(struct hstate *h,
struct list_head *folio_list,
struct list_head *non_hvo_folios)
{
struct folio *folio, *t_folio;
if (!list_empty(non_hvo_folios)) {
/*
* Free any restored hugetlb pages so that restore of the
* entire list can be retried.
* The idea is that in the common case of ENOMEM errors freeing
* hugetlb pages with vmemmap we will free up memory so that we
* can allocate vmemmap for more hugetlb pages.
*/
list_for_each_entry_safe(folio, t_folio, non_hvo_folios, lru) {
list_del(&folio->lru);
spin_lock_irq(&hugetlb_lock);
__folio_clear_hugetlb(folio);
spin_unlock_irq(&hugetlb_lock);
update_and_free_hugetlb_folio(h, folio, false);
cond_resched();
}
} else {
/*
* In the case where there are no folios which can be
* immediately freed, we loop through the list trying to restore
* vmemmap individually in the hope that someone elsewhere may
* have done something to cause success (such as freeing some
* memory). If unable to restore a hugetlb page, the hugetlb
* page is made a surplus page and removed from the list.
* If are able to restore vmemmap and free one hugetlb page, we
* quit processing the list to retry the bulk operation.
*/
list_for_each_entry_safe(folio, t_folio, folio_list, lru)
if (hugetlb_vmemmap_restore_folio(h, folio)) {
list_del(&folio->lru);
spin_lock_irq(&hugetlb_lock);
add_hugetlb_folio(h, folio, true);
spin_unlock_irq(&hugetlb_lock);
} else {
list_del(&folio->lru);
spin_lock_irq(&hugetlb_lock);
__folio_clear_hugetlb(folio);
spin_unlock_irq(&hugetlb_lock);
update_and_free_hugetlb_folio(h, folio, false);
cond_resched();
break;
}
}
}
static void update_and_free_pages_bulk(struct hstate *h,
struct list_head *folio_list)
{
long ret;
struct folio *folio, *t_folio;
LIST_HEAD(non_hvo_folios);
/*
* First allocate required vmemmmap (if necessary) for all folios.
* Carefully handle errors and free up any available hugetlb pages
* in an effort to make forward progress.
*/
retry:
ret = hugetlb_vmemmap_restore_folios(h, folio_list, &non_hvo_folios);
if (ret < 0) {
bulk_vmemmap_restore_error(h, folio_list, &non_hvo_folios);
goto retry;
}
/*
* At this point, list should be empty, ret should be >= 0 and there
* should only be pages on the non_hvo_folios list.
* Do note that the non_hvo_folios list could be empty.
* Without HVO enabled, ret will be 0 and there is no need to call
* __folio_clear_hugetlb as this was done previously.
*/
VM_WARN_ON(!list_empty(folio_list));
VM_WARN_ON(ret < 0);
if (!list_empty(&non_hvo_folios) && ret) {
spin_lock_irq(&hugetlb_lock);
list_for_each_entry(folio, &non_hvo_folios, lru)
__folio_clear_hugetlb(folio);
spin_unlock_irq(&hugetlb_lock);
}
list_for_each_entry_safe(folio, t_folio, &non_hvo_folios, lru) {
update_and_free_hugetlb_folio(h, folio, false);
cond_resched();
}
}
struct hstate *size_to_hstate(unsigned long size)
{
struct hstate *h;
for_each_hstate(h) {
if (huge_page_size(h) == size)
return h;
}
return NULL;
}
void free_huge_folio(struct folio *folio)
{
/*
* Can't pass hstate in here because it is called from the
* generic mm code.
*/
struct hstate *h = folio_hstate(folio);
int nid = folio_nid(folio);
struct hugepage_subpool *spool = hugetlb_folio_subpool(folio);
bool restore_reserve;
unsigned long flags;
VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);
VM_BUG_ON_FOLIO(folio_mapcount(folio), folio);
hugetlb_set_folio_subpool(folio, NULL);
if (folio_test_anon(folio))
__ClearPageAnonExclusive(&folio->page);
folio->mapping = NULL;
restore_reserve = folio_test_hugetlb_restore_reserve(folio);
folio_clear_hugetlb_restore_reserve(folio);
/*
* If HPageRestoreReserve was set on page, page allocation consumed a
* reservation. If the page was associated with a subpool, there
* would have been a page reserved in the subpool before allocation
* via hugepage_subpool_get_pages(). Since we are 'restoring' the
* reservation, do not call hugepage_subpool_put_pages() as this will
* remove the reserved page from the subpool.
*/
if (!restore_reserve) {
/*
* A return code of zero implies that the subpool will be
* under its minimum size if the reservation is not restored
* after page is free. Therefore, force restore_reserve
* operation.
*/
if (hugepage_subpool_put_pages(spool, 1) == 0)
restore_reserve = true;
}
spin_lock_irqsave(&hugetlb_lock, flags);
folio_clear_hugetlb_migratable(folio);
hugetlb_cgroup_uncharge_folio(hstate_index(h),
pages_per_huge_page(h), folio);
hugetlb_cgroup_uncharge_folio_rsvd(hstate_index(h),
pages_per_huge_page(h), folio);
mem_cgroup_uncharge(folio);
if (restore_reserve)
h->resv_huge_pages++;
if (folio_test_hugetlb_temporary(folio)) {
remove_hugetlb_folio(h, folio, false);
spin_unlock_irqrestore(&hugetlb_lock, flags);
update_and_free_hugetlb_folio(h, folio, true);
} else if (h->surplus_huge_pages_node[nid]) {
/* remove the page from active list */
remove_hugetlb_folio(h, folio, true);
spin_unlock_irqrestore(&hugetlb_lock, flags);
update_and_free_hugetlb_folio(h, folio, true);
} else {
arch_clear_hugetlb_flags(folio);
enqueue_hugetlb_folio(h, folio);
spin_unlock_irqrestore(&hugetlb_lock, flags);
}
}
/*
* Must be called with the hugetlb lock held
*/
static void __prep_account_new_huge_page(struct hstate *h, int nid)
{
lockdep_assert_held(&hugetlb_lock);
h->nr_huge_pages++;
h->nr_huge_pages_node[nid]++;
}
static void init_new_hugetlb_folio(struct hstate *h, struct folio *folio)
{
__folio_set_hugetlb(folio);
INIT_LIST_HEAD(&folio->lru);
hugetlb_set_folio_subpool(folio, NULL);
set_hugetlb_cgroup(folio, NULL);
set_hugetlb_cgroup_rsvd(folio, NULL);
}
static void __prep_new_hugetlb_folio(struct hstate *h, struct folio *folio)
{
init_new_hugetlb_folio(h, folio);
hugetlb_vmemmap_optimize_folio(h, folio);
}
static void prep_new_hugetlb_folio(struct hstate *h, struct folio *folio, int nid)
{
__prep_new_hugetlb_folio(h, folio);
spin_lock_irq(&hugetlb_lock);
__prep_account_new_huge_page(h, nid);
spin_unlock_irq(&hugetlb_lock);
}
static bool __prep_compound_gigantic_folio(struct folio *folio,
unsigned int order, bool demote)
{
int i, j;
int nr_pages = 1 << order;
struct page *p;
__folio_clear_reserved(folio);
for (i = 0; i < nr_pages; i++) {
p = folio_page(folio, i);
/*
* For gigantic hugepages allocated through bootmem at
* boot, it's safer to be consistent with the not-gigantic
* hugepages and clear the PG_reserved bit from all tail pages
* too. Otherwise drivers using get_user_pages() to access tail
* pages may get the reference counting wrong if they see
* PG_reserved set on a tail page (despite the head page not
* having PG_reserved set). Enforcing this consistency between
* head and tail pages allows drivers to optimize away a check
* on the head page when they need know if put_page() is needed
* after get_user_pages().
*/
if (i != 0) /* head page cleared above */
__ClearPageReserved(p);
/*
* Subtle and very unlikely
*
* Gigantic 'page allocators' such as memblock or cma will
* return a set of pages with each page ref counted. We need
* to turn this set of pages into a compound page with tail
* page ref counts set to zero. Code such as speculative page
* cache adding could take a ref on a 'to be' tail page.
* We need to respect any increased ref count, and only set
* the ref count to zero if count is currently 1. If count
* is not 1, we return an error. An error return indicates
* the set of pages can not be converted to a gigantic page.
* The caller who allocated the pages should then discard the
* pages using the appropriate free interface.
*
* In the case of demote, the ref count will be zero.
*/
if (!demote) {
if (!page_ref_freeze(p, 1)) {
pr_warn("HugeTLB page can not be used due to unexpected inflated ref count\n");
goto out_error;
}
} else {
VM_BUG_ON_PAGE(page_count(p), p);
}
if (i != 0)
set_compound_head(p, &folio->page);
}
__folio_set_head(folio);
/* we rely on prep_new_hugetlb_folio to set the hugetlb flag */
folio_set_order(folio, order);
atomic_set(&folio->_entire_mapcount, -1);
atomic_set(&folio->_large_mapcount, -1);
atomic_set(&folio->_pincount, 0);
return true;
out_error:
/* undo page modifications made above */
for (j = 0; j < i; j++) {
p = folio_page(folio, j);
if (j != 0)
clear_compound_head(p);
set_page_refcounted(p);
}
/* need to clear PG_reserved on remaining tail pages */
for (; j < nr_pages; j++) {
p = folio_page(folio, j);
__ClearPageReserved(p);
}
return false;
}
static bool prep_compound_gigantic_folio(struct folio *folio,
unsigned int order)
{
return __prep_compound_gigantic_folio(folio, order, false);
}
static bool prep_compound_gigantic_folio_for_demote(struct folio *folio,
unsigned int order)
{
return __prep_compound_gigantic_folio(folio, order, true);
}
/*
* Find and lock address space (mapping) in write mode.
*
* Upon entry, the folio is locked which means that folio_mapping() is
* stable. Due to locking order, we can only trylock_write. If we can
* not get the lock, simply return NULL to caller.
*/
struct address_space *hugetlb_folio_mapping_lock_write(struct folio *folio)
{
struct address_space *mapping = folio_mapping(folio);
if (!mapping)
return mapping;
if (i_mmap_trylock_write(mapping))
return mapping;
return NULL;
}
static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h,
gfp_t gfp_mask, int nid, nodemask_t *nmask,
nodemask_t *node_alloc_noretry)
{
int order = huge_page_order(h);
struct folio *folio;
bool alloc_try_hard = true;
bool retry = true;
/*
* By default we always try hard to allocate the folio with
* __GFP_RETRY_MAYFAIL flag. However, if we are allocating folios in
* a loop (to adjust global huge page counts) and previous allocation
* failed, do not continue to try hard on the same node. Use the
* node_alloc_noretry bitmap to manage this state information.
*/
if (node_alloc_noretry && node_isset(nid, *node_alloc_noretry))
alloc_try_hard = false;
gfp_mask |= __GFP_COMP|__GFP_NOWARN;
if (alloc_try_hard)
gfp_mask |= __GFP_RETRY_MAYFAIL;
if (nid == NUMA_NO_NODE)
nid = numa_mem_id();
retry:
folio = __folio_alloc(gfp_mask, order, nid, nmask);
/* Ensure hugetlb folio won't have large_rmappable flag set. */
if (folio)
folio_clear_large_rmappable(folio);
if (folio && !folio_ref_freeze(folio, 1)) {
folio_put(folio);
if (retry) { /* retry once */
retry = false;
goto retry;
}
/* WOW! twice in a row. */
pr_warn("HugeTLB unexpected inflated folio ref count\n");
folio = NULL;
}
/*
* If we did not specify __GFP_RETRY_MAYFAIL, but still got a
* folio this indicates an overall state change. Clear bit so
* that we resume normal 'try hard' allocations.
*/
if (node_alloc_noretry && folio && !alloc_try_hard)
node_clear(nid, *node_alloc_noretry);
/*
* If we tried hard to get a folio but failed, set bit so that
* subsequent attempts will not try as hard until there is an
* overall state change.
*/
if (node_alloc_noretry && !folio && alloc_try_hard)
node_set(nid, *node_alloc_noretry);
if (!folio) {
__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
return NULL;
}
__count_vm_event(HTLB_BUDDY_PGALLOC);
return folio;
}
static struct folio *__alloc_fresh_hugetlb_folio(struct hstate *h,
gfp_t gfp_mask, int nid, nodemask_t *nmask,
nodemask_t *node_alloc_noretry)
{
struct folio *folio;
bool retry = false;
retry:
if (hstate_is_gigantic(h))
folio = alloc_gigantic_folio(h, gfp_mask, nid, nmask);
else
folio = alloc_buddy_hugetlb_folio(h, gfp_mask,
nid, nmask, node_alloc_noretry);
if (!folio)
return NULL;
if (hstate_is_gigantic(h)) {
if (!prep_compound_gigantic_folio(folio, huge_page_order(h))) {
/*
* Rare failure to convert pages to compound page.
* Free pages and try again - ONCE!
*/
free_gigantic_folio(folio, huge_page_order(h));
if (!retry) {
retry = true;
goto retry;
}
return NULL;
}
}
return folio;
}
static struct folio *only_alloc_fresh_hugetlb_folio(struct hstate *h,
gfp_t gfp_mask, int nid, nodemask_t *nmask,
nodemask_t *node_alloc_noretry)
{
struct folio *folio;
folio = __alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask,
node_alloc_noretry);
if (folio)
init_new_hugetlb_folio(h, folio);
return folio;
}
/*
* Common helper to allocate a fresh hugetlb page. All specific allocators
* should use this function to get new hugetlb pages
*
* Note that returned page is 'frozen': ref count of head page and all tail
* pages is zero.
*/
static struct folio *alloc_fresh_hugetlb_folio(struct hstate *h,
gfp_t gfp_mask, int nid, nodemask_t *nmask)
{
struct folio *folio;
folio = __alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, NULL);
if (!folio)
return NULL;
prep_new_hugetlb_folio(h, folio, folio_nid(folio));
return folio;
}
static void prep_and_add_allocated_folios(struct hstate *h,
struct list_head *folio_list)
{
unsigned long flags;
struct folio *folio, *tmp_f;
/* Send list for bulk vmemmap optimization processing */
hugetlb_vmemmap_optimize_folios(h, folio_list);
/* Add all new pool pages to free lists in one lock cycle */
spin_lock_irqsave(&hugetlb_lock, flags);
list_for_each_entry_safe(folio, tmp_f, folio_list, lru) {
__prep_account_new_huge_page(h, folio_nid(folio));
enqueue_hugetlb_folio(h, folio);
}
spin_unlock_irqrestore(&hugetlb_lock, flags);
}
/*
* Allocates a fresh hugetlb page in a node interleaved manner. The page
* will later be added to the appropriate hugetlb pool.
*/
static struct folio *alloc_pool_huge_folio(struct hstate *h,
nodemask_t *nodes_allowed,
nodemask_t *node_alloc_noretry,
int *next_node)
{
gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
int nr_nodes, node;
for_each_node_mask_to_alloc(next_node, nr_nodes, node, nodes_allowed) {
struct folio *folio;
folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, node,
nodes_allowed, node_alloc_noretry);
if (folio)
return folio;
}
return NULL;
}
/*
* Remove huge page from pool from next node to free. Attempt to keep
* persistent huge pages more or less balanced over allowed nodes.
* This routine only 'removes' the hugetlb page. The caller must make
* an additional call to free the page to low level allocators.
* Called with hugetlb_lock locked.
*/
static struct folio *remove_pool_hugetlb_folio(struct hstate *h,
nodemask_t *nodes_allowed, bool acct_surplus)
{
int nr_nodes, node;
struct folio *folio = NULL;
lockdep_assert_held(&hugetlb_lock);
for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
/*
* If we're returning unused surplus pages, only examine
* nodes with surplus pages.
*/
if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
!list_empty(&h->hugepage_freelists[node])) {
folio = list_entry(h->hugepage_freelists[node].next,
struct folio, lru);
remove_hugetlb_folio(h, folio, acct_surplus);
break;
}
}
return folio;
}
/*
* Dissolve a given free hugetlb folio into free buddy pages. This function
* does nothing for in-use hugetlb folios and non-hugetlb folios.
* This function returns values like below:
*
* -ENOMEM: failed to allocate vmemmap pages to free the freed hugepages
* when the system is under memory pressure and the feature of
* freeing unused vmemmap pages associated with each hugetlb page
* is enabled.
* -EBUSY: failed to dissolved free hugepages or the hugepage is in-use
* (allocated or reserved.)
* 0: successfully dissolved free hugepages or the page is not a
* hugepage (considered as already dissolved)
*/
int dissolve_free_hugetlb_folio(struct folio *folio)
{
int rc = -EBUSY;
retry:
/* Not to disrupt normal path by vainly holding hugetlb_lock */
if (!folio_test_hugetlb(folio))
return 0;
spin_lock_irq(&hugetlb_lock);
if (!folio_test_hugetlb(folio)) {
rc = 0;
goto out;
}
if (!folio_ref_count(folio)) {
struct hstate *h = folio_hstate(folio);
if (!available_huge_pages(h))
goto out;
/*
* We should make sure that the page is already on the free list
* when it is dissolved.
*/
if (unlikely(!folio_test_hugetlb_freed(folio))) {
spin_unlock_irq(&hugetlb_lock);
cond_resched();
/*
* Theoretically, we should return -EBUSY when we
* encounter this race. In fact, we have a chance
* to successfully dissolve the page if we do a
* retry. Because the race window is quite small.
* If we seize this opportunity, it is an optimization
* for increasing the success rate of dissolving page.
*/
goto retry;
}
remove_hugetlb_folio(h, folio, false);
h->max_huge_pages--;
spin_unlock_irq(&hugetlb_lock);
/*
* Normally update_and_free_hugtlb_folio will allocate required vmemmmap
* before freeing the page. update_and_free_hugtlb_folio will fail to
* free the page if it can not allocate required vmemmap. We
* need to adjust max_huge_pages if the page is not freed.
* Attempt to allocate vmemmmap here so that we can take
* appropriate action on failure.
*
* The folio_test_hugetlb check here is because
* remove_hugetlb_folio will clear hugetlb folio flag for
* non-vmemmap optimized hugetlb folios.
*/
if (folio_test_hugetlb(folio)) {
rc = hugetlb_vmemmap_restore_folio(h, folio);
if (rc) {
spin_lock_irq(&hugetlb_lock);
add_hugetlb_folio(h, folio, false);
h->max_huge_pages++;
goto out;
}
} else
rc = 0;
update_and_free_hugetlb_folio(h, folio, false);
return rc;
}
out:
spin_unlock_irq(&hugetlb_lock);
return rc;
}
/*
* Dissolve free hugepages in a given pfn range. Used by memory hotplug to
* make specified memory blocks removable from the system.
* Note that this will dissolve a free gigantic hugepage completely, if any
* part of it lies within the given range.
* Also note that if dissolve_free_hugetlb_folio() returns with an error, all
* free hugetlb folios that were dissolved before that error are lost.
*/
int dissolve_free_hugetlb_folios(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
struct folio *folio;
int rc = 0;
unsigned int order;
struct hstate *h;
if (!hugepages_supported())
return rc;
order = huge_page_order(&default_hstate);
for_each_hstate(h)
order = min(order, huge_page_order(h));
for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) {
folio = pfn_folio(pfn);
rc = dissolve_free_hugetlb_folio(folio);
if (rc)
break;
}
return rc;
}
/*
* Allocates a fresh surplus page from the page allocator.
*/
static struct folio *alloc_surplus_hugetlb_folio(struct hstate *h,
gfp_t gfp_mask, int nid, nodemask_t *nmask)
{
struct folio *folio = NULL;
if (hstate_is_gigantic(h))
return NULL;
spin_lock_irq(&hugetlb_lock);
if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages)
goto out_unlock;
spin_unlock_irq(&hugetlb_lock);
folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask);
if (!folio)
return NULL;
spin_lock_irq(&hugetlb_lock);
/*
* We could have raced with the pool size change.
* Double check that and simply deallocate the new page
* if we would end up overcommiting the surpluses. Abuse
* temporary page to workaround the nasty free_huge_folio
* codeflow
*/
if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
folio_set_hugetlb_temporary(folio);
spin_unlock_irq(&hugetlb_lock);
free_huge_folio(folio);
return NULL;
}
h->surplus_huge_pages++;
h->surplus_huge_pages_node[folio_nid(folio)]++;
out_unlock:
spin_unlock_irq(&hugetlb_lock);
return folio;
}
static struct folio *alloc_migrate_hugetlb_folio(struct hstate *h, gfp_t gfp_mask,
int nid, nodemask_t *nmask)
{
struct folio *folio;
if (hstate_is_gigantic(h))
return NULL;
folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask);
if (!folio)
return NULL;
/* fresh huge pages are frozen */
folio_ref_unfreeze(folio, 1);
/*
* We do not account these pages as surplus because they are only
* temporary and will be released properly on the last reference
*/
folio_set_hugetlb_temporary(folio);
return folio;
}
/*
* Use the VMA's mpolicy to allocate a huge page from the buddy.
*/
static
struct folio *alloc_buddy_hugetlb_folio_with_mpol(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
struct folio *folio = NULL;
struct mempolicy *mpol;
gfp_t gfp_mask = htlb_alloc_mask(h);
int nid;
nodemask_t *nodemask;
nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
if (mpol_is_preferred_many(mpol)) {
gfp_t gfp = gfp_mask | __GFP_NOWARN;
gfp &= ~(__GFP_DIRECT_RECLAIM | __GFP_NOFAIL);
folio = alloc_surplus_hugetlb_folio(h, gfp, nid, nodemask);
/* Fallback to all nodes if page==NULL */
nodemask = NULL;
}
if (!folio)
folio = alloc_surplus_hugetlb_folio(h, gfp_mask, nid, nodemask);
mpol_cond_put(mpol);
return folio;
}
/* folio migration callback function */
struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid,
nodemask_t *nmask, gfp_t gfp_mask, bool allow_alloc_fallback)
{
spin_lock_irq(&hugetlb_lock);
if (available_huge_pages(h)) {
struct folio *folio;
folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask,
preferred_nid, nmask);
if (folio) {
spin_unlock_irq(&hugetlb_lock);
return folio;
}
}
spin_unlock_irq(&hugetlb_lock);
/* We cannot fallback to other nodes, as we could break the per-node pool. */
if (!allow_alloc_fallback)
gfp_mask |= __GFP_THISNODE;
return alloc_migrate_hugetlb_folio(h, gfp_mask, preferred_nid, nmask);
}
static nodemask_t *policy_mbind_nodemask(gfp_t gfp)
{
#ifdef CONFIG_NUMA
struct mempolicy *mpol = get_task_policy(current);
/*
* Only enforce MPOL_BIND policy which overlaps with cpuset policy
* (from policy_nodemask) specifically for hugetlb case
*/
if (mpol->mode == MPOL_BIND &&
(apply_policy_zone(mpol, gfp_zone(gfp)) &&
cpuset_nodemask_valid_mems_allowed(&mpol->nodes)))
return &mpol->nodes;
#endif
return NULL;
}
/*
* Increase the hugetlb pool such that it can accommodate a reservation
* of size 'delta'.
*/
static int gather_surplus_pages(struct hstate *h, long delta)
__must_hold(&hugetlb_lock)
{
LIST_HEAD(surplus_list);
struct folio *folio, *tmp;
int ret;
long i;
long needed, allocated;
bool alloc_ok = true;
int node;
nodemask_t *mbind_nodemask = policy_mbind_nodemask(htlb_alloc_mask(h));
lockdep_assert_held(&hugetlb_lock);
needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
if (needed <= 0) {
h->resv_huge_pages += delta;
return 0;
}
allocated = 0;
ret = -ENOMEM;
retry:
spin_unlock_irq(&hugetlb_lock);
for (i = 0; i < needed; i++) {
folio = NULL;
for_each_node_mask(node, cpuset_current_mems_allowed) {
if (!mbind_nodemask || node_isset(node, *mbind_nodemask)) {
folio = alloc_surplus_hugetlb_folio(h, htlb_alloc_mask(h),
node, NULL);
if (folio)
break;
}
}
if (!folio) {
alloc_ok = false;
break;
}
list_add(&folio->lru, &surplus_list);
cond_resched();
}
allocated += i;
/*
* After retaking hugetlb_lock, we need to recalculate 'needed'
* because either resv_huge_pages or free_huge_pages may have changed.
*/
spin_lock_irq(&hugetlb_lock);
needed = (h->resv_huge_pages + delta) -
(h->free_huge_pages + allocated);
if (needed > 0) {
if (alloc_ok)
goto retry;
/*
* We were not able to allocate enough pages to
* satisfy the entire reservation so we free what
* we've allocated so far.
*/
goto free;
}
/*
* The surplus_list now contains _at_least_ the number of extra pages
* needed to accommodate the reservation. Add the appropriate number
* of pages to the hugetlb pool and free the extras back to the buddy
* allocator. Commit the entire reservation here to prevent another
* process from stealing the pages as they are added to the pool but
* before they are reserved.
*/
needed += allocated;
h->resv_huge_pages += delta;
ret = 0;
/* Free the needed pages to the hugetlb pool */
list_for_each_entry_safe(folio, tmp, &surplus_list, lru) {
if ((--needed) < 0)
break;
/* Add the page to the hugetlb allocator */
enqueue_hugetlb_folio(h, folio);
}
free:
spin_unlock_irq(&hugetlb_lock);
/*
* Free unnecessary surplus pages to the buddy allocator.
* Pages have no ref count, call free_huge_folio directly.
*/
list_for_each_entry_safe(folio, tmp, &surplus_list, lru)
free_huge_folio(folio);
spin_lock_irq(&hugetlb_lock);
return ret;
}
/*
* This routine has two main purposes:
* 1) Decrement the reservation count (resv_huge_pages) by the value passed
* in unused_resv_pages. This corresponds to the prior adjustments made
* to the associated reservation map.
* 2) Free any unused surplus pages that may have been allocated to satisfy
* the reservation. As many as unused_resv_pages may be freed.
*/
static void return_unused_surplus_pages(struct hstate *h,
unsigned long unused_resv_pages)
{
unsigned long nr_pages;
LIST_HEAD(page_list);
lockdep_assert_held(&hugetlb_lock);
/* Uncommit the reservation */
h->resv_huge_pages -= unused_resv_pages;
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
goto out;
/*
* Part (or even all) of the reservation could have been backed
* by pre-allocated pages. Only free surplus pages.
*/
nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
/*
* We want to release as many surplus pages as possible, spread
* evenly across all nodes with memory. Iterate across these nodes
* until we can no longer free unreserved surplus pages. This occurs
* when the nodes with surplus pages have no free pages.
* remove_pool_hugetlb_folio() will balance the freed pages across the
* on-line nodes with memory and will handle the hstate accounting.
*/
while (nr_pages--) {
struct folio *folio;
folio = remove_pool_hugetlb_folio(h, &node_states[N_MEMORY], 1);
if (!folio)
goto out;
list_add(&folio->lru, &page_list);
}
out:
spin_unlock_irq(&hugetlb_lock);
update_and_free_pages_bulk(h, &page_list);
spin_lock_irq(&hugetlb_lock);
}
/*
* vma_needs_reservation, vma_commit_reservation and vma_end_reservation
* are used by the huge page allocation routines to manage reservations.
*
* vma_needs_reservation is called to determine if the huge page at addr
* within the vma has an associated reservation. If a reservation is
* needed, the value 1 is returned. The caller is then responsible for
* managing the global reservation and subpool usage counts. After
* the huge page has been allocated, vma_commit_reservation is called
* to add the page to the reservation map. If the page allocation fails,
* the reservation must be ended instead of committed. vma_end_reservation
* is called in such cases.
*
* In the normal case, vma_commit_reservation returns the same value
* as the preceding vma_needs_reservation call. The only time this
* is not the case is if a reserve map was changed between calls. It
* is the responsibility of the caller to notice the difference and
* take appropriate action.
*
* vma_add_reservation is used in error paths where a reservation must
* be restored when a newly allocated huge page must be freed. It is
* to be called after calling vma_needs_reservation to determine if a
* reservation exists.
*
* vma_del_reservation is used in error paths where an entry in the reserve
* map was created during huge page allocation and must be removed. It is to
* be called after calling vma_needs_reservation to determine if a reservation
* exists.
*/
enum vma_resv_mode {
VMA_NEEDS_RESV,
VMA_COMMIT_RESV,
VMA_END_RESV,
VMA_ADD_RESV,
VMA_DEL_RESV,
};
static long __vma_reservation_common(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr,
enum vma_resv_mode mode)
{
struct resv_map *resv;
pgoff_t idx;
long ret;
long dummy_out_regions_needed;
resv = vma_resv_map(vma);
if (!resv)
return 1;
idx = vma_hugecache_offset(h, vma, addr);
switch (mode) {
case VMA_NEEDS_RESV:
ret = region_chg(resv, idx, idx + 1, &dummy_out_regions_needed);
/* We assume that vma_reservation_* routines always operate on
* 1 page, and that adding to resv map a 1 page entry can only
* ever require 1 region.
*/
VM_BUG_ON(dummy_out_regions_needed != 1);
break;
case VMA_COMMIT_RESV:
ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
/* region_add calls of range 1 should never fail. */
VM_BUG_ON(ret < 0);
break;
case VMA_END_RESV:
region_abort(resv, idx, idx + 1, 1);
ret = 0;
break;
case VMA_ADD_RESV:
if (vma->vm_flags & VM_MAYSHARE) {
ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
/* region_add calls of range 1 should never fail. */
VM_BUG_ON(ret < 0);
} else {
region_abort(resv, idx, idx + 1, 1);
ret = region_del(resv, idx, idx + 1);
}
break;
case VMA_DEL_RESV:
if (vma->vm_flags & VM_MAYSHARE) {
region_abort(resv, idx, idx + 1, 1);
ret = region_del(resv, idx, idx + 1);
} else {
ret = region_add(resv, idx, idx + 1, 1, NULL, NULL);
/* region_add calls of range 1 should never fail. */
VM_BUG_ON(ret < 0);
}
break;
default:
BUG();
}
if (vma->vm_flags & VM_MAYSHARE || mode == VMA_DEL_RESV)
return ret;
/*
* We know private mapping must have HPAGE_RESV_OWNER set.
*
* In most cases, reserves always exist for private mappings.
* However, a file associated with mapping could have been
* hole punched or truncated after reserves were consumed.
* As subsequent fault on such a range will not use reserves.
* Subtle - The reserve map for private mappings has the
* opposite meaning than that of shared mappings. If NO
* entry is in the reserve map, it means a reservation exists.
* If an entry exists in the reserve map, it means the
* reservation has already been consumed. As a result, the
* return value of this routine is the opposite of the
* value returned from reserve map manipulation routines above.
*/
if (ret > 0)
return 0;
if (ret == 0)
return 1;
return ret;
}
static long vma_needs_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
}
static long vma_commit_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
}
static void vma_end_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
}
static long vma_add_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
return __vma_reservation_common(h, vma, addr, VMA_ADD_RESV);
}
static long vma_del_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
return __vma_reservation_common(h, vma, addr, VMA_DEL_RESV);
}
/*
* This routine is called to restore reservation information on error paths.
* It should ONLY be called for folios allocated via alloc_hugetlb_folio(),
* and the hugetlb mutex should remain held when calling this routine.
*
* It handles two specific cases:
* 1) A reservation was in place and the folio consumed the reservation.
* hugetlb_restore_reserve is set in the folio.
* 2) No reservation was in place for the page, so hugetlb_restore_reserve is
* not set. However, alloc_hugetlb_folio always updates the reserve map.
*
* In case 1, free_huge_folio later in the error path will increment the
* global reserve count. But, free_huge_folio does not have enough context
* to adjust the reservation map. This case deals primarily with private
* mappings. Adjust the reserve map here to be consistent with global
* reserve count adjustments to be made by free_huge_folio. Make sure the
* reserve map indicates there is a reservation present.
*
* In case 2, simply undo reserve map modifications done by alloc_hugetlb_folio.
*/
void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma,
unsigned long address, struct folio *folio)
{
long rc = vma_needs_reservation(h, vma, address);
if (folio_test_hugetlb_restore_reserve(folio)) {
if (unlikely(rc < 0))
/*
* Rare out of memory condition in reserve map
* manipulation. Clear hugetlb_restore_reserve so
* that global reserve count will not be incremented
* by free_huge_folio. This will make it appear
* as though the reservation for this folio was
* consumed. This may prevent the task from
* faulting in the folio at a later time. This
* is better than inconsistent global huge page
* accounting of reserve counts.
*/
folio_clear_hugetlb_restore_reserve(folio);
else if (rc)
(void)vma_add_reservation(h, vma, address);
else
vma_end_reservation(h, vma, address);
} else {
if (!rc) {
/*
* This indicates there is an entry in the reserve map
* not added by alloc_hugetlb_folio. We know it was added
* before the alloc_hugetlb_folio call, otherwise
* hugetlb_restore_reserve would be set on the folio.
* Remove the entry so that a subsequent allocation
* does not consume a reservation.
*/
rc = vma_del_reservation(h, vma, address);
if (rc < 0)
/*
* VERY rare out of memory condition. Since
* we can not delete the entry, set
* hugetlb_restore_reserve so that the reserve
* count will be incremented when the folio
* is freed. This reserve will be consumed
* on a subsequent allocation.
*/
folio_set_hugetlb_restore_reserve(folio);
} else if (rc < 0) {
/*
* Rare out of memory condition from
* vma_needs_reservation call. Memory allocation is
* only attempted if a new entry is needed. Therefore,
* this implies there is not an entry in the
* reserve map.
*
* For shared mappings, no entry in the map indicates
* no reservation. We are done.
*/
if (!(vma->vm_flags & VM_MAYSHARE))
/*
* For private mappings, no entry indicates
* a reservation is present. Since we can
* not add an entry, set hugetlb_restore_reserve
* on the folio so reserve count will be
* incremented when freed. This reserve will
* be consumed on a subsequent allocation.
*/
folio_set_hugetlb_restore_reserve(folio);
} else
/*
* No reservation present, do nothing
*/
vma_end_reservation(h, vma, address);
}
}
/*
* alloc_and_dissolve_hugetlb_folio - Allocate a new folio and dissolve
* the old one
* @h: struct hstate old page belongs to
* @old_folio: Old folio to dissolve
* @list: List to isolate the page in case we need to
* Returns 0 on success, otherwise negated error.
*/
static int alloc_and_dissolve_hugetlb_folio(struct hstate *h,
struct folio *old_folio, struct list_head *list)
{
gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
int nid = folio_nid(old_folio);
struct folio *new_folio = NULL;
int ret = 0;
retry:
spin_lock_irq(&hugetlb_lock);
if (!folio_test_hugetlb(old_folio)) {
/*
* Freed from under us. Drop new_folio too.
*/
goto free_new;
} else if (folio_ref_count(old_folio)) {
bool isolated;
/*
* Someone has grabbed the folio, try to isolate it here.
* Fail with -EBUSY if not possible.
*/
spin_unlock_irq(&hugetlb_lock);
isolated = isolate_hugetlb(old_folio, list);
ret = isolated ? 0 : -EBUSY;
spin_lock_irq(&hugetlb_lock);
goto free_new;
} else if (!folio_test_hugetlb_freed(old_folio)) {
/*
* Folio's refcount is 0 but it has not been enqueued in the
* freelist yet. Race window is small, so we can succeed here if
* we retry.
*/
spin_unlock_irq(&hugetlb_lock);
cond_resched();
goto retry;
} else {
if (!new_folio) {
spin_unlock_irq(&hugetlb_lock);
new_folio = alloc_buddy_hugetlb_folio(h, gfp_mask, nid,
NULL, NULL);
if (!new_folio)
return -ENOMEM;
__prep_new_hugetlb_folio(h, new_folio);
goto retry;
}
/*
* Ok, old_folio is still a genuine free hugepage. Remove it from
* the freelist and decrease the counters. These will be
* incremented again when calling __prep_account_new_huge_page()
* and enqueue_hugetlb_folio() for new_folio. The counters will
* remain stable since this happens under the lock.
*/
remove_hugetlb_folio(h, old_folio, false);
/*
* Ref count on new_folio is already zero as it was dropped
* earlier. It can be directly added to the pool free list.
*/
__prep_account_new_huge_page(h, nid);
enqueue_hugetlb_folio(h, new_folio);
/*
* Folio has been replaced, we can safely free the old one.
*/
spin_unlock_irq(&hugetlb_lock);
update_and_free_hugetlb_folio(h, old_folio, false);
}
return ret;
free_new:
spin_unlock_irq(&hugetlb_lock);
if (new_folio)
update_and_free_hugetlb_folio(h, new_folio, false);
return ret;
}
int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
{
struct hstate *h;
struct folio *folio = page_folio(page);
int ret = -EBUSY;
/*
* The page might have been dissolved from under our feet, so make sure
* to carefully check the state under the lock.
* Return success when racing as if we dissolved the page ourselves.
*/
spin_lock_irq(&hugetlb_lock);
if (folio_test_hugetlb(folio)) {
h = folio_hstate(folio);
} else {
spin_unlock_irq(&hugetlb_lock);
return 0;
}
spin_unlock_irq(&hugetlb_lock);
/*
* Fence off gigantic pages as there is a cyclic dependency between
* alloc_contig_range and them. Return -ENOMEM as this has the effect
* of bailing out right away without further retrying.
*/
if (hstate_is_gigantic(h))
return -ENOMEM;
if (folio_ref_count(folio) && isolate_hugetlb(folio, list))
ret = 0;
else if (!folio_ref_count(folio))
ret = alloc_and_dissolve_hugetlb_folio(h, folio, list);
return ret;
}
struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
unsigned long addr, int avoid_reserve)
{
struct hugepage_subpool *spool = subpool_vma(vma);
struct hstate *h = hstate_vma(vma);
struct folio *folio;
long map_chg, map_commit, nr_pages = pages_per_huge_page(h);
long gbl_chg;
int memcg_charge_ret, ret, idx;
struct hugetlb_cgroup *h_cg = NULL;
struct mem_cgroup *memcg;
bool deferred_reserve;
gfp_t gfp = htlb_alloc_mask(h) | __GFP_RETRY_MAYFAIL;
memcg = get_mem_cgroup_from_current();
memcg_charge_ret = mem_cgroup_hugetlb_try_charge(memcg, gfp, nr_pages);
if (memcg_charge_ret == -ENOMEM) {
mem_cgroup_put(memcg);
return ERR_PTR(-ENOMEM);
}
idx = hstate_index(h);
/*
* Examine the region/reserve map to determine if the process
* has a reservation for the page to be allocated. A return
* code of zero indicates a reservation exists (no change).
*/
map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
if (map_chg < 0) {
if (!memcg_charge_ret)
mem_cgroup_cancel_charge(memcg, nr_pages);
mem_cgroup_put(memcg);
return ERR_PTR(-ENOMEM);
}
/*
* Processes that did not create the mapping will have no
* reserves as indicated by the region/reserve map. Check
* that the allocation will not exceed the subpool limit.
* Allocations for MAP_NORESERVE mappings also need to be
* checked against any subpool limit.
*/
if (map_chg || avoid_reserve) {
gbl_chg = hugepage_subpool_get_pages(spool, 1);
if (gbl_chg < 0)
goto out_end_reservation;
/*
* Even though there was no reservation in the region/reserve
* map, there could be reservations associated with the
* subpool that can be used. This would be indicated if the
* return value of hugepage_subpool_get_pages() is zero.
* However, if avoid_reserve is specified we still avoid even
* the subpool reservations.
*/
if (avoid_reserve)
gbl_chg = 1;
}
/* If this allocation is not consuming a reservation, charge it now.
*/
deferred_reserve = map_chg || avoid_reserve;
if (deferred_reserve) {
ret = hugetlb_cgroup_charge_cgroup_rsvd(
idx, pages_per_huge_page(h), &h_cg);
if (ret)
goto out_subpool_put;
}
ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
if (ret)
goto out_uncharge_cgroup_reservation;
spin_lock_irq(&hugetlb_lock);
/*
* glb_chg is passed to indicate whether or not a page must be taken
* from the global free pool (global change). gbl_chg == 0 indicates
* a reservation exists for the allocation.
*/
folio = dequeue_hugetlb_folio_vma(h, vma, addr, avoid_reserve, gbl_chg);
if (!folio) {
spin_unlock_irq(&hugetlb_lock);
folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);
if (!folio)
goto out_uncharge_cgroup;
spin_lock_irq(&hugetlb_lock);
if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
folio_set_hugetlb_restore_reserve(folio);
h->resv_huge_pages--;
}
list_add(&folio->lru, &h->hugepage_activelist);
folio_ref_unfreeze(folio, 1);
/* Fall through */
}
hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, folio);
/* If allocation is not consuming a reservation, also store the
* hugetlb_cgroup pointer on the page.
*/
if (deferred_reserve) {
hugetlb_cgroup_commit_charge_rsvd(idx, pages_per_huge_page(h),
h_cg, folio);
}
spin_unlock_irq(&hugetlb_lock);
hugetlb_set_folio_subpool(folio, spool);
map_commit = vma_commit_reservation(h, vma, addr);
if (unlikely(map_chg > map_commit)) {
/*
* The page was added to the reservation map between
* vma_needs_reservation and vma_commit_reservation.
* This indicates a race with hugetlb_reserve_pages.
* Adjust for the subpool count incremented above AND
* in hugetlb_reserve_pages for the same page. Also,
* the reservation count added in hugetlb_reserve_pages
* no longer applies.
*/
long rsv_adjust;
rsv_adjust = hugepage_subpool_put_pages(spool, 1);
hugetlb_acct_memory(h, -rsv_adjust);
if (deferred_reserve) {
spin_lock_irq(&hugetlb_lock);
hugetlb_cgroup_uncharge_folio_rsvd(hstate_index(h),
pages_per_huge_page(h), folio);
spin_unlock_irq(&hugetlb_lock);
}
}
if (!memcg_charge_ret)
mem_cgroup_commit_charge(folio, memcg);
mem_cgroup_put(memcg);
return folio;
out_uncharge_cgroup:
hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
out_uncharge_cgroup_reservation:
if (deferred_reserve)
hugetlb_cgroup_uncharge_cgroup_rsvd(idx, pages_per_huge_page(h),
h_cg);
out_subpool_put:
if (map_chg || avoid_reserve)
hugepage_subpool_put_pages(spool, 1);
out_end_reservation:
vma_end_reservation(h, vma, addr);
if (!memcg_charge_ret)
mem_cgroup_cancel_charge(memcg, nr_pages);
mem_cgroup_put(memcg);
return ERR_PTR(-ENOSPC);
}
int alloc_bootmem_huge_page(struct hstate *h, int nid)
__attribute__ ((weak, alias("__alloc_bootmem_huge_page")));
int __alloc_bootmem_huge_page(struct hstate *h, int nid)
{
struct huge_bootmem_page *m = NULL; /* initialize for clang */
int nr_nodes, node = nid;
/* do node specific alloc */
if (nid != NUMA_NO_NODE) {
m = memblock_alloc_try_nid_raw(huge_page_size(h), huge_page_size(h),
0, MEMBLOCK_ALLOC_ACCESSIBLE, nid);
if (!m)
return 0;
goto found;
}
/* allocate from next node when distributing huge pages */
for_each_node_mask_to_alloc(&h->next_nid_to_alloc, nr_nodes, node, &node_states[N_MEMORY]) {
m = memblock_alloc_try_nid_raw(
huge_page_size(h), huge_page_size(h),
0, MEMBLOCK_ALLOC_ACCESSIBLE, node);
/*
* Use the beginning of the huge page to store the
* huge_bootmem_page struct (until gather_bootmem
* puts them into the mem_map).
*/
if (!m)
return 0;
goto found;
}
found:
/*
* Only initialize the head struct page in memmap_init_reserved_pages,
* rest of the struct pages will be initialized by the HugeTLB
* subsystem itself.
* The head struct page is used to get folio information by the HugeTLB
* subsystem like zone id and node id.
*/
memblock_reserved_mark_noinit(virt_to_phys((void *)m + PAGE_SIZE),
huge_page_size(h) - PAGE_SIZE);
/* Put them into a private list first because mem_map is not up yet */
INIT_LIST_HEAD(&m->list);
list_add(&m->list, &huge_boot_pages[node]);
m->hstate = h;
return 1;
}
/* Initialize [start_page:end_page_number] tail struct pages of a hugepage */
static void __init hugetlb_folio_init_tail_vmemmap(struct folio *folio,
unsigned long start_page_number,
unsigned long end_page_number)
{
enum zone_type zone = zone_idx(folio_zone(folio));
int nid = folio_nid(folio);
unsigned long head_pfn = folio_pfn(folio);
unsigned long pfn, end_pfn = head_pfn + end_page_number;
int ret;
for (pfn = head_pfn + start_page_number; pfn < end_pfn; pfn++) {
struct page *page = pfn_to_page(pfn);
__init_single_page(page, pfn, zone, nid);
prep_compound_tail((struct page *)folio, pfn - head_pfn);
ret = page_ref_freeze(page, 1);
VM_BUG_ON(!ret);
}
}
static void __init hugetlb_folio_init_vmemmap(struct folio *folio,
struct hstate *h,
unsigned long nr_pages)
{
int ret;
/* Prepare folio head */
__folio_clear_reserved(folio);
__folio_set_head(folio);
ret = folio_ref_freeze(folio, 1);
VM_BUG_ON(!ret);
/* Initialize the necessary tail struct pages */
hugetlb_folio_init_tail_vmemmap(folio, 1, nr_pages);
prep_compound_head((struct page *)folio, huge_page_order(h));
}
static void __init prep_and_add_bootmem_folios(struct hstate *h,
struct list_head *folio_list)
{
unsigned long flags;
struct folio *folio, *tmp_f;
/* Send list for bulk vmemmap optimization processing */
hugetlb_vmemmap_optimize_folios(h, folio_list);
list_for_each_entry_safe(folio, tmp_f, folio_list, lru) {
if (!folio_test_hugetlb_vmemmap_optimized(folio)) {
/*
* If HVO fails, initialize all tail struct pages
* We do not worry about potential long lock hold
* time as this is early in boot and there should
* be no contention.
*/
hugetlb_folio_init_tail_vmemmap(folio,
HUGETLB_VMEMMAP_RESERVE_PAGES,
pages_per_huge_page(h));
}
/* Subdivide locks to achieve better parallel performance */
spin_lock_irqsave(&hugetlb_lock, flags);
__prep_account_new_huge_page(h, folio_nid(folio));
enqueue_hugetlb_folio(h, folio);
spin_unlock_irqrestore(&hugetlb_lock, flags);
}
}
/*
* Put bootmem huge pages into the standard lists after mem_map is up.
* Note: This only applies to gigantic (order > MAX_PAGE_ORDER) pages.
*/
static void __init gather_bootmem_prealloc_node(unsigned long nid)
{
LIST_HEAD(folio_list);
struct huge_bootmem_page *m;
struct hstate *h = NULL, *prev_h = NULL;
list_for_each_entry(m, &huge_boot_pages[nid], list) {
struct page *page = virt_to_page(m);
struct folio *folio = (void *)page;
h = m->hstate;
/*
* It is possible to have multiple huge page sizes (hstates)
* in this list. If so, process each size separately.
*/
if (h != prev_h && prev_h != NULL)
prep_and_add_bootmem_folios(prev_h, &folio_list);
prev_h = h;
VM_BUG_ON(!hstate_is_gigantic(h));
WARN_ON(folio_ref_count(folio) != 1);
hugetlb_folio_init_vmemmap(folio, h,
HUGETLB_VMEMMAP_RESERVE_PAGES);
init_new_hugetlb_folio(h, folio);
list_add(&folio->lru, &folio_list);
/*
* We need to restore the 'stolen' pages to totalram_pages
* in order to fix confusing memory reports from free(1) and
* other side-effects, like CommitLimit going negative.
*/
adjust_managed_page_count(page, pages_per_huge_page(h));
cond_resched();
}
prep_and_add_bootmem_folios(h, &folio_list);
}
static void __init gather_bootmem_prealloc_parallel(unsigned long start,
unsigned long end, void *arg)
{
int nid;
for (nid = start; nid < end; nid++)
gather_bootmem_prealloc_node(nid);
}
static void __init gather_bootmem_prealloc(void)
{
struct padata_mt_job job = {
.thread_fn = gather_bootmem_prealloc_parallel,
.fn_arg = NULL,
.start = 0,
.size = num_node_state(N_MEMORY),
.align = 1,
.min_chunk = 1,
.max_threads = num_node_state(N_MEMORY),
.numa_aware = true,
};
padata_do_multithreaded(&job);
}
static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
{
unsigned long i;
char buf[32];
for (i = 0; i < h->max_huge_pages_node[nid]; ++i) {
if (hstate_is_gigantic(h)) {
if (!alloc_bootmem_huge_page(h, nid))
break;
} else {
struct folio *folio;
gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid,
&node_states[N_MEMORY]);
if (!folio)
break;
free_huge_folio(folio); /* free it into the hugepage allocator */
}
cond_resched();
}
if (i == h->max_huge_pages_node[nid])
return;
string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
pr_warn("HugeTLB: allocating %u of page size %s failed node%d. Only allocated %lu hugepages.\n",
h->max_huge_pages_node[nid], buf, nid, i);
h->max_huge_pages -= (h->max_huge_pages_node[nid] - i);
h->max_huge_pages_node[nid] = i;
}
static bool __init hugetlb_hstate_alloc_pages_specific_nodes(struct hstate *h)
{
int i;
bool node_specific_alloc = false;
for_each_online_node(i) {
if (h->max_huge_pages_node[i] > 0) {
hugetlb_hstate_alloc_pages_onenode(h, i);
node_specific_alloc = true;
}
}
return node_specific_alloc;
}
static void __init hugetlb_hstate_alloc_pages_errcheck(unsigned long allocated, struct hstate *h)
{
if (allocated < h->max_huge_pages) {
char buf[32];
string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
pr_warn("HugeTLB: allocating %lu of page size %s failed. Only allocated %lu hugepages.\n",
h->max_huge_pages, buf, allocated);
h->max_huge_pages = allocated;
}
}
static void __init hugetlb_pages_alloc_boot_node(unsigned long start, unsigned long end, void *arg)
{
struct hstate *h = (struct hstate *)arg;
int i, num = end - start;
nodemask_t node_alloc_noretry;
LIST_HEAD(folio_list);
int next_node = first_online_node;
/* Bit mask controlling how hard we retry per-node allocations.*/
nodes_clear(node_alloc_noretry);
for (i = 0; i < num; ++i) {
struct folio *folio = alloc_pool_huge_folio(h, &node_states[N_MEMORY],
&node_alloc_noretry, &next_node);
if (!folio)
break;
list_move(&folio->lru, &folio_list);
cond_resched();
}
prep_and_add_allocated_folios(h, &folio_list);
}
static unsigned long __init hugetlb_gigantic_pages_alloc_boot(struct hstate *h)
{
unsigned long i;
for (i = 0; i < h->max_huge_pages; ++i) {
if (!alloc_bootmem_huge_page(h, NUMA_NO_NODE))
break;
cond_resched();
}
return i;
}
static unsigned long __init hugetlb_pages_alloc_boot(struct hstate *h)
{
struct padata_mt_job job = {
.fn_arg = h,
.align = 1,
.numa_aware = true
};
job.thread_fn = hugetlb_pages_alloc_boot_node;
job.start = 0;
job.size = h->max_huge_pages;
/*
* job.max_threads is twice the num_node_state(N_MEMORY),
*
* Tests below indicate that a multiplier of 2 significantly improves
* performance, and although larger values also provide improvements,
* the gains are marginal.
*
* Therefore, choosing 2 as the multiplier strikes a good balance between
* enhancing parallel processing capabilities and maintaining efficient
* resource management.
*
* +------------+-------+-------+-------+-------+-------+
* | multiplier | 1 | 2 | 3 | 4 | 5 |
* +------------+-------+-------+-------+-------+-------+
* | 256G 2node | 358ms | 215ms | 157ms | 134ms | 126ms |
* | 2T 4node | 979ms | 679ms | 543ms | 489ms | 481ms |
* | 50G 2node | 71ms | 44ms | 37ms | 30ms | 31ms |
* +------------+-------+-------+-------+-------+-------+
*/
job.max_threads = num_node_state(N_MEMORY) * 2;
job.min_chunk = h->max_huge_pages / num_node_state(N_MEMORY) / 2;
padata_do_multithreaded(&job);
return h->nr_huge_pages;
}
/*
* NOTE: this routine is called in different contexts for gigantic and
* non-gigantic pages.
* - For gigantic pages, this is called early in the boot process and
* pages are allocated from memblock allocated or something similar.
* Gigantic pages are actually added to pools later with the routine
* gather_bootmem_prealloc.
* - For non-gigantic pages, this is called later in the boot process after
* all of mm is up and functional. Pages are allocated from buddy and
* then added to hugetlb pools.
*/
static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
{
unsigned long allocated;
static bool initialized __initdata;
/* skip gigantic hugepages allocation if hugetlb_cma enabled */
if (hstate_is_gigantic(h) && hugetlb_cma_size) {
pr_warn_once("HugeTLB: hugetlb_cma is enabled, skip boot time allocation\n");
return;
}
/* hugetlb_hstate_alloc_pages will be called many times, initialize huge_boot_pages once */
if (!initialized) {
int i = 0;
for (i = 0; i < MAX_NUMNODES; i++)
INIT_LIST_HEAD(&huge_boot_pages[i]);
initialized = true;
}
/* do node specific alloc */
if (hugetlb_hstate_alloc_pages_specific_nodes(h))
return;
/* below will do all node balanced alloc */
if (hstate_is_gigantic(h))
allocated = hugetlb_gigantic_pages_alloc_boot(h);
else
allocated = hugetlb_pages_alloc_boot(h);
hugetlb_hstate_alloc_pages_errcheck(allocated, h);
}
static void __init hugetlb_init_hstates(void)
{
struct hstate *h, *h2;
for_each_hstate(h) {
/* oversize hugepages were init'ed in early boot */
if (!hstate_is_gigantic(h))
hugetlb_hstate_alloc_pages(h);
/*
* Set demote order for each hstate. Note that
* h->demote_order is initially 0.
* - We can not demote gigantic pages if runtime freeing
* is not supported, so skip this.
* - If CMA allocation is possible, we can not demote
* HUGETLB_PAGE_ORDER or smaller size pages.
*/
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
continue;
if (hugetlb_cma_size && h->order <= HUGETLB_PAGE_ORDER)
continue;
for_each_hstate(h2) {
if (h2 == h)
continue;
if (h2->order < h->order &&
h2->order > h->demote_order)
h->demote_order = h2->order;
}
}
}
static void __init report_hugepages(void)
{
struct hstate *h;
for_each_hstate(h) {
char buf[32];
string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
pr_info("HugeTLB: registered %s page size, pre-allocated %ld pages\n",
buf, h->free_huge_pages);
pr_info("HugeTLB: %d KiB vmemmap can be freed for a %s page\n",
hugetlb_vmemmap_optimizable_size(h) / SZ_1K, buf);
}
}
#ifdef CONFIG_HIGHMEM
static void try_to_free_low(struct hstate *h, unsigned long count,
nodemask_t *nodes_allowed)
{
int i;
LIST_HEAD(page_list);
lockdep_assert_held(&hugetlb_lock);
if (hstate_is_gigantic(h))
return;
/*
* Collect pages to be freed on a list, and free after dropping lock
*/
for_each_node_mask(i, *nodes_allowed) {
struct folio *folio, *next;
struct list_head *freel = &h->hugepage_freelists[i];
list_for_each_entry_safe(folio, next, freel, lru) {
if (count >= h->nr_huge_pages)
goto out;
if (folio_test_highmem(folio))
continue;
remove_hugetlb_folio(h, folio, false);
list_add(&folio->lru, &page_list);
}
}
out:
spin_unlock_irq(&hugetlb_lock);
update_and_free_pages_bulk(h, &page_list);
spin_lock_irq(&hugetlb_lock);
}
#else
static inline void try_to_free_low(struct hstate *h, unsigned long count,
nodemask_t *nodes_allowed)
{
}
#endif
/*
* Increment or decrement surplus_huge_pages. Keep node-specific counters
* balanced by operating on them in a round-robin fashion.
* Returns 1 if an adjustment was made.
*/
static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
int delta)
{
int nr_nodes, node;
lockdep_assert_held(&hugetlb_lock);
VM_BUG_ON(delta != -1 && delta != 1);
if (delta < 0) {
for_each_node_mask_to_alloc(&h->next_nid_to_alloc, nr_nodes, node, nodes_allowed) {
if (h->surplus_huge_pages_node[node])
goto found;
}
} else {
for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
if (h->surplus_huge_pages_node[node] <
h->nr_huge_pages_node[node])
goto found;
}
}
return 0;
found:
h->surplus_huge_pages += delta;
h->surplus_huge_pages_node[node] += delta;
return 1;
}
#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
nodemask_t *nodes_allowed)
{
unsigned long min_count;
unsigned long allocated;
struct folio *folio;
LIST_HEAD(page_list);
NODEMASK_ALLOC(nodemask_t, node_alloc_noretry, GFP_KERNEL);
/*
* Bit mask controlling how hard we retry per-node allocations.
* If we can not allocate the bit mask, do not attempt to allocate
* the requested huge pages.
*/
if (node_alloc_noretry)
nodes_clear(*node_alloc_noretry);
else
return -ENOMEM;
/*
* resize_lock mutex prevents concurrent adjustments to number of
* pages in hstate via the proc/sysfs interfaces.
*/
mutex_lock(&h->resize_lock);
flush_free_hpage_work(h);
spin_lock_irq(&hugetlb_lock);
/*
* Check for a node specific request.
* Changing node specific huge page count may require a corresponding
* change to the global count. In any case, the passed node mask
* (nodes_allowed) will restrict alloc/free to the specified node.
*/
if (nid != NUMA_NO_NODE) {
unsigned long old_count = count;
count += persistent_huge_pages(h) -
(h->nr_huge_pages_node[nid] -
h->surplus_huge_pages_node[nid]);
/*
* User may have specified a large count value which caused the
* above calculation to overflow. In this case, they wanted
* to allocate as many huge pages as possible. Set count to
* largest possible value to align with their intention.
*/
if (count < old_count)
count = ULONG_MAX;
}
/*
* Gigantic pages runtime allocation depend on the capability for large
* page range allocation.
* If the system does not provide this feature, return an error when
* the user tries to allocate gigantic pages but let the user free the
* boottime allocated gigantic pages.
*/
if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
if (count > persistent_huge_pages(h)) {
spin_unlock_irq(&hugetlb_lock);
mutex_unlock(&h->resize_lock);
NODEMASK_FREE(node_alloc_noretry);
return -EINVAL;
}
/* Fall through to decrease pool */
}
/*
* Increase the pool size
* First take pages out of surplus state. Then make up the
* remaining difference by allocating fresh huge pages.
*
* We might race with alloc_surplus_hugetlb_folio() here and be unable
* to convert a surplus huge page to a normal huge page. That is
* not critical, though, it just means the overall size of the
* pool might be one hugepage larger than it needs to be, but
* within all the constraints specified by the sysctls.
*/
while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
if (!adjust_pool_surplus(h, nodes_allowed, -1))
break;
}
allocated = 0;
while (count > (persistent_huge_pages(h) + allocated)) {
/*
* If this allocation races such that we no longer need the
* page, free_huge_folio will handle it by freeing the page
* and reducing the surplus.
*/
spin_unlock_irq(&hugetlb_lock);
/* yield cpu to avoid soft lockup */
cond_resched();
folio = alloc_pool_huge_folio(h, nodes_allowed,
node_alloc_noretry,
&h->next_nid_to_alloc);
if (!folio) {
prep_and_add_allocated_folios(h, &page_list);
spin_lock_irq(&hugetlb_lock);
goto out;
}
list_add(&folio->lru, &page_list);
allocated++;
/* Bail for signals. Probably ctrl-c from user */
if (signal_pending(current)) {
prep_and_add_allocated_folios(h, &page_list);
spin_lock_irq(&hugetlb_lock);
goto out;
}
spin_lock_irq(&hugetlb_lock);
}
/* Add allocated pages to the pool */
if (!list_empty(&page_list)) {
spin_unlock_irq(&hugetlb_lock);
prep_and_add_allocated_folios(h, &page_list);
spin_lock_irq(&hugetlb_lock);
}
/*
* Decrease the pool size
* First return free pages to the buddy allocator (being careful
* to keep enough around to satisfy reservations). Then place
* pages into surplus state as needed so the pool will shrink
* to the desired size as pages become free.
*
* By placing pages into the surplus state independent of the
* overcommit value, we are allowing the surplus pool size to
* exceed overcommit. There are few sane options here. Since
* alloc_surplus_hugetlb_folio() is checking the global counter,
* though, we'll note that we're not allowed to exceed surplus
* and won't grow the pool anywhere else. Not until one of the
* sysctls are changed, or the surplus pages go out of use.
*/
min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
min_count = max(count, min_count);
try_to_free_low(h, min_count, nodes_allowed);
/*
* Collect pages to be removed on list without dropping lock
*/
while (min_count < persistent_huge_pages(h)) {
folio = remove_pool_hugetlb_folio(h, nodes_allowed, 0);
if (!folio)
break;
list_add(&folio->lru, &page_list);
}
/* free the pages after dropping lock */
spin_unlock_irq(&hugetlb_lock);
update_and_free_pages_bulk(h, &page_list);
flush_free_hpage_work(h);
spin_lock_irq(&hugetlb_lock);
while (count < persistent_huge_pages(h)) {
if (!adjust_pool_surplus(h, nodes_allowed, 1))
break;
}
out:
h->max_huge_pages = persistent_huge_pages(h);
spin_unlock_irq(&hugetlb_lock);
mutex_unlock(&h->resize_lock);
NODEMASK_FREE(node_alloc_noretry);
return 0;
}
static int demote_free_hugetlb_folio(struct hstate *h, struct folio *folio)
{
int i, nid = folio_nid(folio);
struct hstate *target_hstate;
struct page *subpage;
struct folio *inner_folio;
int rc = 0;
target_hstate = size_to_hstate(PAGE_SIZE << h->demote_order);
remove_hugetlb_folio(h, folio, false);
spin_unlock_irq(&hugetlb_lock);
/*
* If vmemmap already existed for folio, the remove routine above would
* have cleared the hugetlb folio flag. Hence the folio is technically
* no longer a hugetlb folio. hugetlb_vmemmap_restore_folio can only be
* passed hugetlb folios and will BUG otherwise.
*/
if (folio_test_hugetlb(folio)) {
rc = hugetlb_vmemmap_restore_folio(h, folio);
if (rc) {
/* Allocation of vmemmmap failed, we can not demote folio */
spin_lock_irq(&hugetlb_lock);
add_hugetlb_folio(h, folio, false);
return rc;
}
}
/*
* Use destroy_compound_hugetlb_folio_for_demote for all huge page
* sizes as it will not ref count folios.
*/
destroy_compound_hugetlb_folio_for_demote(folio, huge_page_order(h));
/*
* Taking target hstate mutex synchronizes with set_max_huge_pages.
* Without the mutex, pages added to target hstate could be marked
* as surplus.
*
* Note that we already hold h->resize_lock. To prevent deadlock,
* use the convention of always taking larger size hstate mutex first.
*/
mutex_lock(&target_hstate->resize_lock);
for (i = 0; i < pages_per_huge_page(h);
i += pages_per_huge_page(target_hstate)) {
subpage = folio_page(folio, i);
inner_folio = page_folio(subpage);
if (hstate_is_gigantic(target_hstate))
prep_compound_gigantic_folio_for_demote(inner_folio,
target_hstate->order);
else
prep_compound_page(subpage, target_hstate->order);
folio_change_private(inner_folio, NULL);
prep_new_hugetlb_folio(target_hstate, inner_folio, nid);
free_huge_folio(inner_folio);
}
mutex_unlock(&target_hstate->resize_lock);
spin_lock_irq(&hugetlb_lock);
/*
* Not absolutely necessary, but for consistency update max_huge_pages
* based on pool changes for the demoted page.
*/
h->max_huge_pages--;
target_hstate->max_huge_pages +=
pages_per_huge_page(h) / pages_per_huge_page(target_hstate);
return rc;
}
static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
__must_hold(&hugetlb_lock)
{
int nr_nodes, node;
struct folio *folio;
lockdep_assert_held(&hugetlb_lock);
/* We should never get here if no demote order */
if (!h->demote_order) {
pr_warn("HugeTLB: NULL demote order passed to demote_pool_huge_page.\n");
return -EINVAL; /* internal error */
}
for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
list_for_each_entry(folio, &h->hugepage_freelists[node], lru) {
if (folio_test_hwpoison(folio))
continue;
return demote_free_hugetlb_folio(h, folio);
}
}
/*
* Only way to get here is if all pages on free lists are poisoned.
* Return -EBUSY so that caller will not retry.
*/
return -EBUSY;
}
#define HSTATE_ATTR_RO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
#define HSTATE_ATTR_WO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_WO(_name)
#define HSTATE_ATTR(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RW(_name)
static struct kobject *hugepages_kobj;
static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
{
int i;
for (i = 0; i < HUGE_MAX_HSTATE; i++)
if (hstate_kobjs[i] == kobj) {
if (nidp)
*nidp = NUMA_NO_NODE;
return &hstates[i];
}
return kobj_to_node_hstate(kobj, nidp);
}
static ssize_t nr_hugepages_show_common(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h;
unsigned long nr_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
nr_huge_pages = h->nr_huge_pages;
else
nr_huge_pages = h->nr_huge_pages_node[nid];
return sysfs_emit(buf, "%lu\n", nr_huge_pages);
}
static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
struct hstate *h, int nid,
unsigned long count, size_t len)
{
int err;
nodemask_t nodes_allowed, *n_mask;
if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
return -EINVAL;
if (nid == NUMA_NO_NODE) {
/*
* global hstate attribute
*/
if (!(obey_mempolicy &&
init_nodemask_of_mempolicy(&nodes_allowed)))
n_mask = &node_states[N_MEMORY];
else
n_mask = &nodes_allowed;
} else {
/*
* Node specific request. count adjustment happens in
* set_max_huge_pages() after acquiring hugetlb_lock.
*/
init_nodemask_of_node(&nodes_allowed, nid);
n_mask = &nodes_allowed;
}
err = set_max_huge_pages(h, count, nid, n_mask);
return err ? err : len;
}
static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
struct kobject *kobj, const char *buf,
size_t len)
{
struct hstate *h;
unsigned long count;
int nid;
int err;
err = kstrtoul(buf, 10, &count);
if (err)
return err;
h = kobj_to_hstate(kobj, &nid);
return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
}
static ssize_t nr_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return nr_hugepages_show_common(kobj, attr, buf);
}
static ssize_t nr_hugepages_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t len)
{
return nr_hugepages_store_common(false, kobj, buf, len);
}
HSTATE_ATTR(nr_hugepages);
#ifdef CONFIG_NUMA
/*
* hstate attribute for optionally mempolicy-based constraint on persistent
* huge page alloc/free.
*/
static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
return nr_hugepages_show_common(kobj, attr, buf);
}
static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t len)
{
return nr_hugepages_store_common(true, kobj, buf, len);
}
HSTATE_ATTR(nr_hugepages_mempolicy);
#endif
static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h = kobj_to_hstate(kobj, NULL);
return sysfs_emit(buf, "%lu\n", h->nr_overcommit_huge_pages);
}
static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t count)
{
int err;
unsigned long input;
struct hstate *h = kobj_to_hstate(kobj, NULL);
if (hstate_is_gigantic(h))
return -EINVAL;
err = kstrtoul(buf, 10, &input);
if (err)
return err;
spin_lock_irq(&hugetlb_lock);
h->nr_overcommit_huge_pages = input;
spin_unlock_irq(&hugetlb_lock);
return count;
}
HSTATE_ATTR(nr_overcommit_hugepages);
static ssize_t free_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h;
unsigned long free_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
free_huge_pages = h->free_huge_pages;
else
free_huge_pages = h->free_huge_pages_node[nid];
return sysfs_emit(buf, "%lu\n", free_huge_pages);
}
HSTATE_ATTR_RO(free_hugepages);
static ssize_t resv_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h = kobj_to_hstate(kobj, NULL);
return sysfs_emit(buf, "%lu\n", h->resv_huge_pages);
}
HSTATE_ATTR_RO(resv_hugepages);
static ssize_t surplus_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h;
unsigned long surplus_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
surplus_huge_pages = h->surplus_huge_pages;
else
surplus_huge_pages = h->surplus_huge_pages_node[nid];
return sysfs_emit(buf, "%lu\n", surplus_huge_pages);
}
HSTATE_ATTR_RO(surplus_hugepages);
static ssize_t demote_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t len)
{
unsigned long nr_demote;
unsigned long nr_available;
nodemask_t nodes_allowed, *n_mask;
struct hstate *h;
int err;
int nid;
err = kstrtoul(buf, 10, &nr_demote);
if (err)
return err;
h = kobj_to_hstate(kobj, &nid);
if (nid != NUMA_NO_NODE) {
init_nodemask_of_node(&nodes_allowed, nid);
n_mask = &nodes_allowed;
} else {
n_mask = &node_states[N_MEMORY];
}
/* Synchronize with other sysfs operations modifying huge pages */
mutex_lock(&h->resize_lock);
spin_lock_irq(&hugetlb_lock);
while (nr_demote) {
/*
* Check for available pages to demote each time thorough the
* loop as demote_pool_huge_page will drop hugetlb_lock.
*/
if (nid != NUMA_NO_NODE)
nr_available = h->free_huge_pages_node[nid];
else
nr_available = h->free_huge_pages;
nr_available -= h->resv_huge_pages;
if (!nr_available)
break;
err = demote_pool_huge_page(h, n_mask);
if (err)
break;
nr_demote--;
}
spin_unlock_irq(&hugetlb_lock);
mutex_unlock(&h->resize_lock);
if (err)
return err;
return len;
}
HSTATE_ATTR_WO(demote);
static ssize_t demote_size_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h = kobj_to_hstate(kobj, NULL);
unsigned long demote_size = (PAGE_SIZE << h->demote_order) / SZ_1K;
return sysfs_emit(buf, "%lukB\n", demote_size);
}
static ssize_t demote_size_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
struct hstate *h, *demote_hstate;
unsigned long demote_size;
unsigned int demote_order;
demote_size = (unsigned long)memparse(buf, NULL);
demote_hstate = size_to_hstate(demote_size);
if (!demote_hstate)
return -EINVAL;
demote_order = demote_hstate->order;
if (demote_order < HUGETLB_PAGE_ORDER)
return -EINVAL;
/* demote order must be smaller than hstate order */
h = kobj_to_hstate(kobj, NULL);
if (demote_order >= h->order)
return -EINVAL;
/* resize_lock synchronizes access to demote size and writes */
mutex_lock(&h->resize_lock);
h->demote_order = demote_order;
mutex_unlock(&h->resize_lock);
return count;
}
HSTATE_ATTR(demote_size);
static struct attribute *hstate_attrs[] = {
&nr_hugepages_attr.attr,
&nr_overcommit_hugepages_attr.attr,
&free_hugepages_attr.attr,
&resv_hugepages_attr.attr,
&surplus_hugepages_attr.attr,
#ifdef CONFIG_NUMA
&nr_hugepages_mempolicy_attr.attr,
#endif
NULL,
};
static const struct attribute_group hstate_attr_group = {
.attrs = hstate_attrs,
};
static struct attribute *hstate_demote_attrs[] = {
&demote_size_attr.attr,
&demote_attr.attr,
NULL,
};
static const struct attribute_group hstate_demote_attr_group = {
.attrs = hstate_demote_attrs,
};
static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
struct kobject **hstate_kobjs,
const struct attribute_group *hstate_attr_group)
{
int retval;
int hi = hstate_index(h);
hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
if (!hstate_kobjs[hi])
return -ENOMEM;
retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
if (retval) {
kobject_put(hstate_kobjs[hi]);
hstate_kobjs[hi] = NULL;
return retval;
}
if (h->demote_order) {
retval = sysfs_create_group(hstate_kobjs[hi],
&hstate_demote_attr_group);
if (retval) {
pr_warn("HugeTLB unable to create demote interfaces for %s\n", h->name);
sysfs_remove_group(hstate_kobjs[hi], hstate_attr_group);
kobject_put(hstate_kobjs[hi]);
hstate_kobjs[hi] = NULL;
return retval;
}
}
return 0;
}
#ifdef CONFIG_NUMA
static bool hugetlb_sysfs_initialized __ro_after_init;
/*
* node_hstate/s - associate per node hstate attributes, via their kobjects,
* with node devices in node_devices[] using a parallel array. The array
* index of a node device or _hstate == node id.
* This is here to avoid any static dependency of the node device driver, in
* the base kernel, on the hugetlb module.
*/
struct node_hstate {
struct kobject *hugepages_kobj;
struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
};
static struct node_hstate node_hstates[MAX_NUMNODES];
/*
* A subset of global hstate attributes for node devices
*/
static struct attribute *per_node_hstate_attrs[] = {
&nr_hugepages_attr.attr,
&free_hugepages_attr.attr,
&surplus_hugepages_attr.attr,
NULL,
};
static const struct attribute_group per_node_hstate_attr_group = {
.attrs = per_node_hstate_attrs,
};
/*
* kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
* Returns node id via non-NULL nidp.
*/
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
{
int nid;
for (nid = 0; nid < nr_node_ids; nid++) {
struct node_hstate *nhs = &node_hstates[nid];
int i;
for (i = 0; i < HUGE_MAX_HSTATE; i++)
if (nhs->hstate_kobjs[i] == kobj) {
if (nidp)
*nidp = nid;
return &hstates[i];
}
}
BUG();
return NULL;
}
/*
* Unregister hstate attributes from a single node device.
* No-op if no hstate attributes attached.
*/
void hugetlb_unregister_node(struct node *node)
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
if (!nhs->hugepages_kobj)
return; /* no hstate attributes */
for_each_hstate(h) {
int idx = hstate_index(h);
struct kobject *hstate_kobj = nhs->hstate_kobjs[idx];
if (!hstate_kobj)
continue;
if (h->demote_order)
sysfs_remove_group(hstate_kobj, &hstate_demote_attr_group);
sysfs_remove_group(hstate_kobj, &per_node_hstate_attr_group);
kobject_put(hstate_kobj);
nhs->hstate_kobjs[idx] = NULL;
}
kobject_put(nhs->hugepages_kobj);
nhs->hugepages_kobj = NULL;
}
/*
* Register hstate attributes for a single node device.
* No-op if attributes already registered.
*/
void hugetlb_register_node(struct node *node)
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
int err;
if (!hugetlb_sysfs_initialized)
return;
if (nhs->hugepages_kobj)
return; /* already allocated */
nhs->hugepages_kobj = kobject_create_and_add("hugepages",
&node->dev.kobj);
if (!nhs->hugepages_kobj)
return;
for_each_hstate(h) {
err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
nhs->hstate_kobjs,
&per_node_hstate_attr_group);
if (err) {
pr_err("HugeTLB: Unable to add hstate %s for node %d\n",
h->name, node->dev.id);
hugetlb_unregister_node(node);
break;
}
}
}
/*
* hugetlb init time: register hstate attributes for all registered node
* devices of nodes that have memory. All on-line nodes should have
* registered their associated device by this time.
*/
static void __init hugetlb_register_all_nodes(void)
{
int nid;
for_each_online_node(nid)
hugetlb_register_node(node_devices[nid]);
}
#else /* !CONFIG_NUMA */
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
{
BUG();
if (nidp)
*nidp = -1;
return NULL;
}
static void hugetlb_register_all_nodes(void) { }
#endif
#ifdef CONFIG_CMA
static void __init hugetlb_cma_check(void);
#else
static inline __init void hugetlb_cma_check(void)
{
}
#endif
static void __init hugetlb_sysfs_init(void)
{
struct hstate *h;
int err;
hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
if (!hugepages_kobj)
return;
for_each_hstate(h) {
err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
hstate_kobjs, &hstate_attr_group);
if (err)
pr_err("HugeTLB: Unable to add hstate %s", h->name);
}
#ifdef CONFIG_NUMA
hugetlb_sysfs_initialized = true;
#endif
hugetlb_register_all_nodes();
}
#ifdef CONFIG_SYSCTL
static void hugetlb_sysctl_init(void);
#else
static inline void hugetlb_sysctl_init(void) { }
#endif
static int __init hugetlb_init(void)
{
int i;
BUILD_BUG_ON(sizeof_field(struct page, private) * BITS_PER_BYTE <
__NR_HPAGEFLAGS);
if (!hugepages_supported()) {
if (hugetlb_max_hstate || default_hstate_max_huge_pages)
pr_warn("HugeTLB: huge pages not supported, ignoring associated command-line parameters\n");
return 0;
}
/*
* Make sure HPAGE_SIZE (HUGETLB_PAGE_ORDER) hstate exists. Some
* architectures depend on setup being done here.
*/
hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
if (!parsed_default_hugepagesz) {
/*
* If we did not parse a default huge page size, set
* default_hstate_idx to HPAGE_SIZE hstate. And, if the
* number of huge pages for this default size was implicitly
* specified, set that here as well.
* Note that the implicit setting will overwrite an explicit
* setting. A warning will be printed in this case.
*/
default_hstate_idx = hstate_index(size_to_hstate(HPAGE_SIZE));
if (default_hstate_max_huge_pages) {
if (default_hstate.max_huge_pages) {
char buf[32];
string_get_size(huge_page_size(&default_hstate),
1, STRING_UNITS_2, buf, 32);
pr_warn("HugeTLB: Ignoring hugepages=%lu associated with %s page size\n",
default_hstate.max_huge_pages, buf);
pr_warn("HugeTLB: Using hugepages=%lu for number of default huge pages\n",
default_hstate_max_huge_pages);
}
default_hstate.max_huge_pages =
default_hstate_max_huge_pages;
for_each_online_node(i)
default_hstate.max_huge_pages_node[i] =
default_hugepages_in_node[i];
}
}
hugetlb_cma_check();
hugetlb_init_hstates();
gather_bootmem_prealloc();
report_hugepages();
hugetlb_sysfs_init();
hugetlb_cgroup_file_init();
hugetlb_sysctl_init();
#ifdef CONFIG_SMP
num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
#else
num_fault_mutexes = 1;
#endif
hugetlb_fault_mutex_table =
kmalloc_array(num_fault_mutexes, sizeof(struct mutex),
GFP_KERNEL);
BUG_ON(!hugetlb_fault_mutex_table);
for (i = 0; i < num_fault_mutexes; i++)
mutex_init(&hugetlb_fault_mutex_table[i]);
return 0;
}
subsys_initcall(hugetlb_init);
/* Overwritten by architectures with more huge page sizes */
bool __init __attribute((weak)) arch_hugetlb_valid_size(unsigned long size)
{
return size == HPAGE_SIZE;
}
void __init hugetlb_add_hstate(unsigned int order)
{
struct hstate *h;
unsigned long i;
if (size_to_hstate(PAGE_SIZE << order)) {
return;
}
BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
BUG_ON(order < order_base_2(__NR_USED_SUBPAGE));
h = &hstates[hugetlb_max_hstate++];
__mutex_init(&h->resize_lock, "resize mutex", &h->resize_key);
h->order = order;
h->mask = ~(huge_page_size(h) - 1);
for (i = 0; i < MAX_NUMNODES; ++i)
INIT_LIST_HEAD(&h->hugepage_freelists[i]);
INIT_LIST_HEAD(&h->hugepage_activelist);
h->next_nid_to_alloc = first_memory_node;
h->next_nid_to_free = first_memory_node;
snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
huge_page_size(h)/SZ_1K);
parsed_hstate = h;
}
bool __init __weak hugetlb_node_alloc_supported(void)
{
return true;
}
static void __init hugepages_clear_pages_in_node(void)
{
if (!hugetlb_max_hstate) {
default_hstate_max_huge_pages = 0;
memset(default_hugepages_in_node, 0,
sizeof(default_hugepages_in_node));
} else {
parsed_hstate->max_huge_pages = 0;
memset(parsed_hstate->max_huge_pages_node, 0,
sizeof(parsed_hstate->max_huge_pages_node));
}
}
/*
* hugepages command line processing
* hugepages normally follows a valid hugepagsz or default_hugepagsz
* specification. If not, ignore the hugepages value. hugepages can also
* be the first huge page command line option in which case it implicitly
* specifies the number of huge pages for the default size.
*/
static int __init hugepages_setup(char *s)
{
unsigned long *mhp;
static unsigned long *last_mhp;
int node = NUMA_NO_NODE;
int count;
unsigned long tmp;
char *p = s;
if (!parsed_valid_hugepagesz) {
pr_warn("HugeTLB: hugepages=%s does not follow a valid hugepagesz, ignoring\n", s);
parsed_valid_hugepagesz = true;
return 1;
}
/*
* !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter
* yet, so this hugepages= parameter goes to the "default hstate".
* Otherwise, it goes with the previously parsed hugepagesz or
* default_hugepagesz.
*/
else if (!hugetlb_max_hstate)
mhp = &default_hstate_max_huge_pages;
else
mhp = &parsed_hstate->max_huge_pages;
if (mhp == last_mhp) {
pr_warn("HugeTLB: hugepages= specified twice without interleaving hugepagesz=, ignoring hugepages=%s\n", s);
return 1;
}
while (*p) {
count = 0;
if (sscanf(p, "%lu%n", &tmp, &count) != 1)
goto invalid;
/* Parameter is node format */
if (p[count] == ':') {
if (!hugetlb_node_alloc_supported()) {
pr_warn("HugeTLB: architecture can't support node specific alloc, ignoring!\n");
return 1;
}
if (tmp >= MAX_NUMNODES || !node_online(tmp))
goto invalid;
node = array_index_nospec(tmp, MAX_NUMNODES);
p += count + 1;
/* Parse hugepages */
if (sscanf(p, "%lu%n", &tmp, &count) != 1)
goto invalid;
if (!hugetlb_max_hstate)
default_hugepages_in_node[node] = tmp;
else
parsed_hstate->max_huge_pages_node[node] = tmp;
*mhp += tmp;
/* Go to parse next node*/
if (p[count] == ',')
p += count + 1;
else
break;
} else {
if (p != s)
goto invalid;
*mhp = tmp;
break;
}
}
/*
* Global state is always initialized later in hugetlb_init.
* But we need to allocate gigantic hstates here early to still
* use the bootmem allocator.
*/
if (hugetlb_max_hstate && hstate_is_gigantic(parsed_hstate))
hugetlb_hstate_alloc_pages(parsed_hstate);
last_mhp = mhp;
return 1;
invalid:
pr_warn("HugeTLB: Invalid hugepages parameter %s\n", p);
hugepages_clear_pages_in_node();
return 1;
}
__setup("hugepages=", hugepages_setup);
/*
* hugepagesz command line processing
* A specific huge page size can only be specified once with hugepagesz.
* hugepagesz is followed by hugepages on the command line. The global
* variable 'parsed_valid_hugepagesz' is used to determine if prior
* hugepagesz argument was valid.
*/
static int __init hugepagesz_setup(char *s)
{
unsigned long size;
struct hstate *h;
parsed_valid_hugepagesz = false;
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
pr_err("HugeTLB: unsupported hugepagesz=%s\n", s);
return 1;
}
h = size_to_hstate(size);
if (h) {
/*
* hstate for this size already exists. This is normally
* an error, but is allowed if the existing hstate is the
* default hstate. More specifically, it is only allowed if
* the number of huge pages for the default hstate was not
* previously specified.
*/
if (!parsed_default_hugepagesz || h != &default_hstate ||
default_hstate.max_huge_pages) {
pr_warn("HugeTLB: hugepagesz=%s specified twice, ignoring\n", s);
return 1;
}
/*
* No need to call hugetlb_add_hstate() as hstate already
* exists. But, do set parsed_hstate so that a following
* hugepages= parameter will be applied to this hstate.
*/
parsed_hstate = h;
parsed_valid_hugepagesz = true;
return 1;
}
hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
parsed_valid_hugepagesz = true;
return 1;
}
__setup("hugepagesz=", hugepagesz_setup);
/*
* default_hugepagesz command line input
* Only one instance of default_hugepagesz allowed on command line.
*/
static int __init default_hugepagesz_setup(char *s)
{
unsigned long size;
int i;
parsed_valid_hugepagesz = false;
if (parsed_default_hugepagesz) {
pr_err("HugeTLB: default_hugepagesz previously specified, ignoring %s\n", s);
return 1;
}
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
pr_err("HugeTLB: unsupported default_hugepagesz=%s\n", s);
return 1;
}
hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
parsed_valid_hugepagesz = true;
parsed_default_hugepagesz = true;
default_hstate_idx = hstate_index(size_to_hstate(size));
/*
* The number of default huge pages (for this size) could have been
* specified as the first hugetlb parameter: hugepages=X. If so,
* then default_hstate_max_huge_pages is set. If the default huge
* page size is gigantic (> MAX_PAGE_ORDER), then the pages must be
* allocated here from bootmem allocator.
*/
if (default_hstate_max_huge_pages) {
default_hstate.max_huge_pages = default_hstate_max_huge_pages;
for_each_online_node(i)
default_hstate.max_huge_pages_node[i] =
default_hugepages_in_node[i];
if (hstate_is_gigantic(&default_hstate))
hugetlb_hstate_alloc_pages(&default_hstate);
default_hstate_max_huge_pages = 0;
}
return 1;
}
__setup("default_hugepagesz=", default_hugepagesz_setup);
static unsigned int allowed_mems_nr(struct hstate *h)
{
int node;
unsigned int nr = 0;
nodemask_t *mbind_nodemask;
unsigned int *array = h->free_huge_pages_node;
gfp_t gfp_mask = htlb_alloc_mask(h);
mbind_nodemask = policy_mbind_nodemask(gfp_mask);
for_each_node_mask(node, cpuset_current_mems_allowed) {
if (!mbind_nodemask || node_isset(node, *mbind_nodemask))
nr += array[node];
}
return nr;
}
#ifdef CONFIG_SYSCTL
static int proc_hugetlb_doulongvec_minmax(const struct ctl_table *table, int write,
void *buffer, size_t *length,
loff_t *ppos, unsigned long *out)
{
struct ctl_table dup_table;
/*
* In order to avoid races with __do_proc_doulongvec_minmax(), we
* can duplicate the @table and alter the duplicate of it.
*/
dup_table = *table;
dup_table.data = out;
return proc_doulongvec_minmax(&dup_table, write, buffer, length, ppos);
}
static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
const struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
struct hstate *h = &default_hstate;
unsigned long tmp = h->max_huge_pages;
int ret;
if (!hugepages_supported())
return -EOPNOTSUPP;
ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos,
&tmp);
if (ret)
goto out;
if (write)
ret = __nr_hugepages_store_common(obey_mempolicy, h,
NUMA_NO_NODE, tmp, *length);
out:
return ret;
}
static int hugetlb_sysctl_handler(const struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
return hugetlb_sysctl_handler_common(false, table, write,
buffer, length, ppos);
}
#ifdef CONFIG_NUMA
static int hugetlb_mempolicy_sysctl_handler(const struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
return hugetlb_sysctl_handler_common(true, table, write,
buffer, length, ppos);
}
#endif /* CONFIG_NUMA */
static int hugetlb_overcommit_handler(const struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
struct hstate *h = &default_hstate;
unsigned long tmp;
int ret;
if (!hugepages_supported())
return -EOPNOTSUPP;
tmp = h->nr_overcommit_huge_pages;
if (write && hstate_is_gigantic(h))
return -EINVAL;
ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos,
&tmp);
if (ret)
goto out;
if (write) {
spin_lock_irq(&hugetlb_lock);
h->nr_overcommit_huge_pages = tmp;
spin_unlock_irq(&hugetlb_lock);
}
out:
return ret;
}
static struct ctl_table hugetlb_table[] = {
{
.procname = "nr_hugepages",
.data = NULL,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = hugetlb_sysctl_handler,
},
#ifdef CONFIG_NUMA
{
.procname = "nr_hugepages_mempolicy",
.data = NULL,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = &hugetlb_mempolicy_sysctl_handler,
},
#endif
{
.procname = "hugetlb_shm_group",
.data = &sysctl_hugetlb_shm_group,
.maxlen = sizeof(gid_t),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "nr_overcommit_hugepages",
.data = NULL,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = hugetlb_overcommit_handler,
},
};
static void hugetlb_sysctl_init(void)
{
register_sysctl_init("vm", hugetlb_table);
}
#endif /* CONFIG_SYSCTL */
void hugetlb_report_meminfo(struct seq_file *m)
{
struct hstate *h;
unsigned long total = 0;
if (!hugepages_supported())
return;
for_each_hstate(h) {
unsigned long count = h->nr_huge_pages;
total += huge_page_size(h) * count;
if (h == &default_hstate)
seq_printf(m,
"HugePages_Total: %5lu\n"
"HugePages_Free: %5lu\n"
"HugePages_Rsvd: %5lu\n"
"HugePages_Surp: %5lu\n"
"Hugepagesize: %8lu kB\n",
count,
h->free_huge_pages,
h->resv_huge_pages,
h->surplus_huge_pages,
huge_page_size(h) / SZ_1K);
}
seq_printf(m, "Hugetlb: %8lu kB\n", total / SZ_1K);
}
int hugetlb_report_node_meminfo(char *buf, int len, int nid)
{
struct hstate *h = &default_hstate;
if (!hugepages_supported())
return 0;
return sysfs_emit_at(buf, len,
"Node %d HugePages_Total: %5u\n"
"Node %d HugePages_Free: %5u\n"
"Node %d HugePages_Surp: %5u\n",
nid, h->nr_huge_pages_node[nid],
nid, h->free_huge_pages_node[nid],
nid, h->surplus_huge_pages_node[nid]);
}
void hugetlb_show_meminfo_node(int nid)
{
struct hstate *h;
if (!hugepages_supported())
return;
for_each_hstate(h)
printk("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
nid,
h->nr_huge_pages_node[nid],
h->free_huge_pages_node[nid],
h->surplus_huge_pages_node[nid],
huge_page_size(h) / SZ_1K);
}
void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
{
seq_printf(m, "HugetlbPages:\t%8lu kB\n",
K(atomic_long_read(&mm->hugetlb_usage)));
}
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
struct hstate *h;
unsigned long nr_total_pages = 0;
for_each_hstate(h)
nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
return nr_total_pages;
}
static int hugetlb_acct_memory(struct hstate *h, long delta)
{
int ret = -ENOMEM;
if (!delta)
return 0;
spin_lock_irq(&hugetlb_lock);
/*
* When cpuset is configured, it breaks the strict hugetlb page
* reservation as the accounting is done on a global variable. Such
* reservation is completely rubbish in the presence of cpuset because
* the reservation is not checked against page availability for the
* current cpuset. Application can still potentially OOM'ed by kernel
* with lack of free htlb page in cpuset that the task is in.
* Attempt to enforce strict accounting with cpuset is almost
* impossible (or too ugly) because cpuset is too fluid that
* task or memory node can be dynamically moved between cpusets.
*
* The change of semantics for shared hugetlb mapping with cpuset is
* undesirable. However, in order to preserve some of the semantics,
* we fall back to check against current free page availability as
* a best attempt and hopefully to minimize the impact of changing
* semantics that cpuset has.
*
* Apart from cpuset, we also have memory policy mechanism that
* also determines from which node the kernel will allocate memory
* in a NUMA system. So similar to cpuset, we also should consider
* the memory policy of the current task. Similar to the description
* above.
*/
if (delta > 0) {
if (gather_surplus_pages(h, delta) < 0)
goto out;
if (delta > allowed_mems_nr(h)) {
return_unused_surplus_pages(h, delta);
goto out;
}
}
ret = 0;
if (delta < 0)
return_unused_surplus_pages(h, (unsigned long) -delta);
out:
spin_unlock_irq(&hugetlb_lock);
return ret;
}
static void hugetlb_vm_op_open(struct vm_area_struct *vma)
{
struct resv_map *resv = vma_resv_map(vma);
/*
* HPAGE_RESV_OWNER indicates a private mapping.
* This new VMA should share its siblings reservation map if present.
* The VMA will only ever have a valid reservation map pointer where
* it is being copied for another still existing VMA. As that VMA
* has a reference to the reservation map it cannot disappear until
* after this open call completes. It is therefore safe to take a
* new reference here without additional locking.
*/
if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
resv_map_dup_hugetlb_cgroup_uncharge_info(resv);
kref_get(&resv->refs);
}
/*
* vma_lock structure for sharable mappings is vma specific.
* Clear old pointer (if copied via vm_area_dup) and allocate
* new structure. Before clearing, make sure vma_lock is not
* for this vma.
*/
if (vma->vm_flags & VM_MAYSHARE) {
struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
if (vma_lock) {
if (vma_lock->vma != vma) {
vma->vm_private_data = NULL;
hugetlb_vma_lock_alloc(vma);
} else
pr_warn("HugeTLB: vma_lock already exists in %s.\n", __func__);
} else
hugetlb_vma_lock_alloc(vma);
}
}
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
struct hstate *h = hstate_vma(vma);
struct resv_map *resv;
struct hugepage_subpool *spool = subpool_vma(vma);
unsigned long reserve, start, end;
long gbl_reserve;
hugetlb_vma_lock_free(vma);
resv = vma_resv_map(vma);
if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
return;
start = vma_hugecache_offset(h, vma, vma->vm_start);
end = vma_hugecache_offset(h, vma, vma->vm_end);
reserve = (end - start) - region_count(resv, start, end);
hugetlb_cgroup_uncharge_counter(resv, start, end);
if (reserve) {
/*
* Decrement reserve counts. The global reserve count may be
* adjusted if the subpool has a minimum size.
*/
gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
hugetlb_acct_memory(h, -gbl_reserve);
}
kref_put(&resv->refs, resv_map_release);
}
static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
{
if (addr & ~(huge_page_mask(hstate_vma(vma))))
return -EINVAL;
/*
* PMD sharing is only possible for PUD_SIZE-aligned address ranges
* in HugeTLB VMAs. If we will lose PUD_SIZE alignment due to this
* split, unshare PMDs in the PUD_SIZE interval surrounding addr now.
*/
if (addr & ~PUD_MASK) {
/*
* hugetlb_vm_op_split is called right before we attempt to
* split the VMA. We will need to unshare PMDs in the old and
* new VMAs, so let's unshare before we split.
*/
unsigned long floor = addr & PUD_MASK;
unsigned long ceil = floor + PUD_SIZE;
if (floor >= vma->vm_start && ceil <= vma->vm_end)
hugetlb_unshare_pmds(vma, floor, ceil);
}
return 0;
}
static unsigned long hugetlb_vm_op_pagesize(struct vm_area_struct *vma)
{
return huge_page_size(hstate_vma(vma));
}
/*
* We cannot handle pagefaults against hugetlb pages at all. They cause
* handle_mm_fault() to try to instantiate regular-sized pages in the
* hugepage VMA. do_page_fault() is supposed to trap this, so BUG is we get
* this far.
*/
static vm_fault_t hugetlb_vm_op_fault(struct vm_fault *vmf)
{
BUG();
return 0;
}
/*
* When a new function is introduced to vm_operations_struct and added
* to hugetlb_vm_ops, please consider adding the function to shm_vm_ops.
* This is because under System V memory model, mappings created via
* shmget/shmat with "huge page" specified are backed by hugetlbfs files,
* their original vm_ops are overwritten with shm_vm_ops.
*/
const struct vm_operations_struct hugetlb_vm_ops = {
.fault = hugetlb_vm_op_fault,
.open = hugetlb_vm_op_open,
.close = hugetlb_vm_op_close,
.may_split = hugetlb_vm_op_split,
.pagesize = hugetlb_vm_op_pagesize,
};
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
int writable)
{
pte_t entry;
unsigned int shift = huge_page_shift(hstate_vma(vma));
if (writable) {
entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
vma->vm_page_prot)));
} else {
entry = huge_pte_wrprotect(mk_huge_pte(page,
vma->vm_page_prot));
}
entry = pte_mkyoung(entry);
entry = arch_make_huge_pte(entry, shift, vma->vm_flags);
return entry;
}
static void set_huge_ptep_writable(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep)
{
pte_t entry;
entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(vma->vm_mm, address, ptep)));
if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
update_mmu_cache(vma, address, ptep);
}
bool is_hugetlb_entry_migration(pte_t pte)
{
swp_entry_t swp;
if (huge_pte_none(pte) || pte_present(pte))
return false;
swp = pte_to_swp_entry(pte);
if (is_migration_entry(swp))
return true;
else
return false;
}
bool is_hugetlb_entry_hwpoisoned(pte_t pte)
{
swp_entry_t swp;
if (huge_pte_none(pte) || pte_present(pte))
return false;
swp = pte_to_swp_entry(pte);
if (is_hwpoison_entry(swp))
return true;
else
return false;
}
static void
hugetlb_install_folio(struct vm_area_struct *vma, pte_t *ptep, unsigned long addr,
struct folio *new_folio, pte_t old, unsigned long sz)
{
pte_t newpte = make_huge_pte(vma, &new_folio->page, 1);
__folio_mark_uptodate(new_folio);
hugetlb_add_new_anon_rmap(new_folio, vma, addr);
if (userfaultfd_wp(vma) && huge_pte_uffd_wp(old))
newpte = huge_pte_mkuffd_wp(newpte);
set_huge_pte_at(vma->vm_mm, addr, ptep, newpte, sz);
hugetlb_count_add(pages_per_huge_page(hstate_vma(vma)), vma->vm_mm);
folio_set_hugetlb_migratable(new_folio);
}
int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
struct vm_area_struct *dst_vma,
struct vm_area_struct *src_vma)
{
pte_t *src_pte, *dst_pte, entry;
struct folio *pte_folio;
unsigned long addr;
bool cow = is_cow_mapping(src_vma->vm_flags);
struct hstate *h = hstate_vma(src_vma);
unsigned long sz = huge_page_size(h);
unsigned long npages = pages_per_huge_page(h);
struct mmu_notifier_range range;
unsigned long last_addr_mask;
int ret = 0;
if (cow) {
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, src,
src_vma->vm_start,
src_vma->vm_end);
mmu_notifier_invalidate_range_start(&range);
vma_assert_write_locked(src_vma);
raw_write_seqcount_begin(&src->write_protect_seq);
} else {
/*
* For shared mappings the vma lock must be held before
* calling hugetlb_walk() in the src vma. Otherwise, the
* returned ptep could go away if part of a shared pmd and
* another thread calls huge_pmd_unshare.
*/
hugetlb_vma_lock_read(src_vma);
}
last_addr_mask = hugetlb_mask_last_page(h);
for (addr = src_vma->vm_start; addr < src_vma->vm_end; addr += sz) {
spinlock_t *src_ptl, *dst_ptl;
src_pte = hugetlb_walk(src_vma, addr, sz);
if (!src_pte) {
addr |= last_addr_mask;
continue;
}
dst_pte = huge_pte_alloc(dst, dst_vma, addr, sz);
if (!dst_pte) {
ret = -ENOMEM;
break;
}
/*
* If the pagetables are shared don't copy or take references.
*
* dst_pte == src_pte is the common case of src/dest sharing.
* However, src could have 'unshared' and dst shares with
* another vma. So page_count of ptep page is checked instead
* to reliably determine whether pte is shared.
*/
if (page_count(virt_to_page(dst_pte)) > 1) {
addr |= last_addr_mask;
continue;
}
dst_ptl = huge_pte_lock(h, dst, dst_pte);
src_ptl = huge_pte_lockptr(h, src, src_pte);
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
entry = huge_ptep_get(src_vma->vm_mm, addr, src_pte);
again:
if (huge_pte_none(entry)) {
/*
* Skip if src entry none.
*/
;
} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) {
if (!userfaultfd_wp(dst_vma))
entry = huge_pte_clear_uffd_wp(entry);
set_huge_pte_at(dst, addr, dst_pte, entry, sz);
} else if (unlikely(is_hugetlb_entry_migration(entry))) {
swp_entry_t swp_entry = pte_to_swp_entry(entry);
bool uffd_wp = pte_swp_uffd_wp(entry);
if (!is_readable_migration_entry(swp_entry) && cow) {
/*
* COW mappings require pages in both
* parent and child to be set to read.
*/
swp_entry = make_readable_migration_entry(
swp_offset(swp_entry));
entry = swp_entry_to_pte(swp_entry);
if (userfaultfd_wp(src_vma) && uffd_wp)
entry = pte_swp_mkuffd_wp(entry);
set_huge_pte_at(src, addr, src_pte, entry, sz);
}
if (!userfaultfd_wp(dst_vma))
entry = huge_pte_clear_uffd_wp(entry);
set_huge_pte_at(dst, addr, dst_pte, entry, sz);
} else if (unlikely(is_pte_marker(entry))) {
pte_marker marker = copy_pte_marker(
pte_to_swp_entry(entry), dst_vma);
if (marker)
set_huge_pte_at(dst, addr, dst_pte,
make_pte_marker(marker), sz);
} else {
entry = huge_ptep_get(src_vma->vm_mm, addr, src_pte);
pte_folio = page_folio(pte_page(entry));
folio_get(pte_folio);
/*
* Failing to duplicate the anon rmap is a rare case
* where we see pinned hugetlb pages while they're
* prone to COW. We need to do the COW earlier during
* fork.
*
* When pre-allocating the page or copying data, we
* need to be without the pgtable locks since we could
* sleep during the process.
*/
if (!folio_test_anon(pte_folio)) {
hugetlb_add_file_rmap(pte_folio);
} else if (hugetlb_try_dup_anon_rmap(pte_folio, src_vma)) {
pte_t src_pte_old = entry;
struct folio *new_folio;
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
/* Do not use reserve as it's private owned */
new_folio = alloc_hugetlb_folio(dst_vma, addr, 1);
if (IS_ERR(new_folio)) {
folio_put(pte_folio);
ret = PTR_ERR(new_folio);
break;
}
ret = copy_user_large_folio(new_folio, pte_folio,
ALIGN_DOWN(addr, sz), dst_vma);
folio_put(pte_folio);
if (ret) {
folio_put(new_folio);
break;
}
/* Install the new hugetlb folio if src pte stable */
dst_ptl = huge_pte_lock(h, dst, dst_pte);
src_ptl = huge_pte_lockptr(h, src, src_pte);
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
entry = huge_ptep_get(src_vma->vm_mm, addr, src_pte);
if (!pte_same(src_pte_old, entry)) {
restore_reserve_on_error(h, dst_vma, addr,
new_folio);
folio_put(new_folio);
/* huge_ptep of dst_pte won't change as in child */
goto again;
}
hugetlb_install_folio(dst_vma, dst_pte, addr,
new_folio, src_pte_old, sz);
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
continue;
}
if (cow) {
/*
* No need to notify as we are downgrading page
* table protection not changing it to point
* to a new page.
*
* See Documentation/mm/mmu_notifier.rst
*/
huge_ptep_set_wrprotect(src, addr, src_pte);
entry = huge_pte_wrprotect(entry);
}
if (!userfaultfd_wp(dst_vma))
entry = huge_pte_clear_uffd_wp(entry);
set_huge_pte_at(dst, addr, dst_pte, entry, sz);
hugetlb_count_add(npages, dst);
}
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
}
if (cow) {
raw_write_seqcount_end(&src->write_protect_seq);
mmu_notifier_invalidate_range_end(&range);
} else {
hugetlb_vma_unlock_read(src_vma);
}
return ret;
}
static void move_huge_pte(struct vm_area_struct *vma, unsigned long old_addr,
unsigned long new_addr, pte_t *src_pte, pte_t *dst_pte,
unsigned long sz)
{
struct hstate *h = hstate_vma(vma);
struct mm_struct *mm = vma->vm_mm;
spinlock_t *src_ptl, *dst_ptl;
pte_t pte;
dst_ptl = huge_pte_lock(h, mm, dst_pte);
src_ptl = huge_pte_lockptr(h, mm, src_pte);
/*
* We don't have to worry about the ordering of src and dst ptlocks
* because exclusive mmap_lock (or the i_mmap_lock) prevents deadlock.
*/
if (src_ptl != dst_ptl)
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
pte = huge_ptep_get_and_clear(mm, old_addr, src_pte);
set_huge_pte_at(mm, new_addr, dst_pte, pte, sz);
if (src_ptl != dst_ptl)
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
}
int move_hugetlb_page_tables(struct vm_area_struct *vma,
struct vm_area_struct *new_vma,
unsigned long old_addr, unsigned long new_addr,
unsigned long len)
{
struct hstate *h = hstate_vma(vma);
struct address_space *mapping = vma->vm_file->f_mapping;
unsigned long sz = huge_page_size(h);
struct mm_struct *mm = vma->vm_mm;
unsigned long old_end = old_addr + len;
unsigned long last_addr_mask;
pte_t *src_pte, *dst_pte;
struct mmu_notifier_range range;
bool shared_pmd = false;
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, old_addr,
old_end);
adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
/*
* In case of shared PMDs, we should cover the maximum possible
* range.
*/
flush_cache_range(vma, range.start, range.end);
mmu_notifier_invalidate_range_start(&range);
last_addr_mask = hugetlb_mask_last_page(h);
/* Prevent race with file truncation */
hugetlb_vma_lock_write(vma);
i_mmap_lock_write(mapping);
for (; old_addr < old_end; old_addr += sz, new_addr += sz) {
src_pte = hugetlb_walk(vma, old_addr, sz);
if (!src_pte) {
old_addr |= last_addr_mask;
new_addr |= last_addr_mask;
continue;
}
if (huge_pte_none(huge_ptep_get(mm, old_addr, src_pte)))
continue;
if (huge_pmd_unshare(mm, vma, old_addr, src_pte)) {
shared_pmd = true;
old_addr |= last_addr_mask;
new_addr |= last_addr_mask;
continue;
}
dst_pte = huge_pte_alloc(mm, new_vma, new_addr, sz);
if (!dst_pte)
break;
move_huge_pte(vma, old_addr, new_addr, src_pte, dst_pte, sz);
}
if (shared_pmd)
flush_hugetlb_tlb_range(vma, range.start, range.end);
else
flush_hugetlb_tlb_range(vma, old_end - len, old_end);
mmu_notifier_invalidate_range_end(&range);
i_mmap_unlock_write(mapping);
hugetlb_vma_unlock_write(vma);
return len + old_addr - old_end;
}
void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct page *ref_page, zap_flags_t zap_flags)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long address;
pte_t *ptep;
pte_t pte;
spinlock_t *ptl;
struct page *page;
struct hstate *h = hstate_vma(vma);
unsigned long sz = huge_page_size(h);
bool adjust_reservation = false;
unsigned long last_addr_mask;
bool force_flush = false;
WARN_ON(!is_vm_hugetlb_page(vma));
BUG_ON(start & ~huge_page_mask(h));
BUG_ON(end & ~huge_page_mask(h));
/*
* This is a hugetlb vma, all the pte entries should point
* to huge page.
*/
tlb_change_page_size(tlb, sz);
tlb_start_vma(tlb, vma);
last_addr_mask = hugetlb_mask_last_page(h);
address = start;
for (; address < end; address += sz) {
ptep = hugetlb_walk(vma, address, sz);
if (!ptep) {
address |= last_addr_mask;
continue;
}
ptl = huge_pte_lock(h, mm, ptep);
if (huge_pmd_unshare(mm, vma, address, ptep)) {
spin_unlock(ptl);
tlb_flush_pmd_range(tlb, address & PUD_MASK, PUD_SIZE);
force_flush = true;
address |= last_addr_mask;
continue;
}
pte = huge_ptep_get(mm, address, ptep);
if (huge_pte_none(pte)) {
spin_unlock(ptl);
continue;
}
/*
* Migrating hugepage or HWPoisoned hugepage is already
* unmapped and its refcount is dropped, so just clear pte here.
*/
if (unlikely(!pte_present(pte))) {
/*
* If the pte was wr-protected by uffd-wp in any of the
* swap forms, meanwhile the caller does not want to
* drop the uffd-wp bit in this zap, then replace the
* pte with a marker.
*/
if (pte_swp_uffd_wp_any(pte) &&
!(zap_flags & ZAP_FLAG_DROP_MARKER))
set_huge_pte_at(mm, address, ptep,
make_pte_marker(PTE_MARKER_UFFD_WP),
sz);
else
huge_pte_clear(mm, address, ptep, sz);
spin_unlock(ptl);
continue;
}
page = pte_page(pte);
/*
* If a reference page is supplied, it is because a specific
* page is being unmapped, not a range. Ensure the page we
* are about to unmap is the actual page of interest.
*/
if (ref_page) {
if (page != ref_page) {
spin_unlock(ptl);
continue;
}
/*
* Mark the VMA as having unmapped its page so that
* future faults in this VMA will fail rather than
* looking like data was lost
*/
set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
}
pte = huge_ptep_get_and_clear(mm, address, ptep);
tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
if (huge_pte_dirty(pte))
set_page_dirty(page);
/* Leave a uffd-wp pte marker if needed */
if (huge_pte_uffd_wp(pte) &&
!(zap_flags & ZAP_FLAG_DROP_MARKER))
set_huge_pte_at(mm, address, ptep,
make_pte_marker(PTE_MARKER_UFFD_WP),
sz);
hugetlb_count_sub(pages_per_huge_page(h), mm);
hugetlb_remove_rmap(page_folio(page));
/*
* Restore the reservation for anonymous page, otherwise the
* backing page could be stolen by someone.
* If there we are freeing a surplus, do not set the restore
* reservation bit.
*/
if (!h->surplus_huge_pages && __vma_private_lock(vma) &&
folio_test_anon(page_folio(page))) {
folio_set_hugetlb_restore_reserve(page_folio(page));
/* Reservation to be adjusted after the spin lock */
adjust_reservation = true;
}
spin_unlock(ptl);
/*
* Adjust the reservation for the region that will have the
* reserve restored. Keep in mind that vma_needs_reservation() changes
* resv->adds_in_progress if it succeeds. If this is not done,
* do_exit() will not see it, and will keep the reservation
* forever.
*/
if (adjust_reservation) {
int rc = vma_needs_reservation(h, vma, address);
if (rc < 0)
/* Pressumably allocate_file_region_entries failed
* to allocate a file_region struct. Clear
* hugetlb_restore_reserve so that global reserve
* count will not be incremented by free_huge_folio.
* Act as if we consumed the reservation.
*/
folio_clear_hugetlb_restore_reserve(page_folio(page));
else if (rc)
vma_add_reservation(h, vma, address);
}
tlb_remove_page_size(tlb, page, huge_page_size(h));
/*
* Bail out after unmapping reference page if supplied
*/
if (ref_page)
break;
}
tlb_end_vma(tlb, vma);
/*
* If we unshared PMDs, the TLB flush was not recorded in mmu_gather. We
* could defer the flush until now, since by holding i_mmap_rwsem we
* guaranteed that the last refernece would not be dropped. But we must
* do the flushing before we return, as otherwise i_mmap_rwsem will be
* dropped and the last reference to the shared PMDs page might be
* dropped as well.
*
* In theory we could defer the freeing of the PMD pages as well, but
* huge_pmd_unshare() relies on the exact page_count for the PMD page to
* detect sharing, so we cannot defer the release of the page either.
* Instead, do flush now.
*/
if (force_flush)
tlb_flush_mmu_tlbonly(tlb);
}
void __hugetlb_zap_begin(struct vm_area_struct *vma,
unsigned long *start, unsigned long *end)
{
if (!vma->vm_file) /* hugetlbfs_file_mmap error */
return;
adjust_range_if_pmd_sharing_possible(vma, start, end);
hugetlb_vma_lock_write(vma);
if (vma->vm_file)
i_mmap_lock_write(vma->vm_file->f_mapping);
}
void __hugetlb_zap_end(struct vm_area_struct *vma,
struct zap_details *details)
{
zap_flags_t zap_flags = details ? details->zap_flags : 0;
if (!vma->vm_file) /* hugetlbfs_file_mmap error */
return;
if (zap_flags & ZAP_FLAG_UNMAP) { /* final unmap */
/*
* Unlock and free the vma lock before releasing i_mmap_rwsem.
* When the vma_lock is freed, this makes the vma ineligible
* for pmd sharing. And, i_mmap_rwsem is required to set up
* pmd sharing. This is important as page tables for this
* unmapped range will be asynchrously deleted. If the page
* tables are shared, there will be issues when accessed by
* someone else.
*/
__hugetlb_vma_unlock_write_free(vma);
} else {
hugetlb_vma_unlock_write(vma);
}
if (vma->vm_file)
i_mmap_unlock_write(vma->vm_file->f_mapping);
}
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end, struct page *ref_page,
zap_flags_t zap_flags)
{
struct mmu_notifier_range range;
struct mmu_gather tlb;
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
start, end);
adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
mmu_notifier_invalidate_range_start(&range);
tlb_gather_mmu(&tlb, vma->vm_mm);
__unmap_hugepage_range(&tlb, vma, start, end, ref_page, zap_flags);
mmu_notifier_invalidate_range_end(&range);
tlb_finish_mmu(&tlb);
}
/*
* This is called when the original mapper is failing to COW a MAP_PRIVATE
* mapping it owns the reserve page for. The intention is to unmap the page
* from other VMAs and let the children be SIGKILLed if they are faulting the
* same region.
*/
static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
struct page *page, unsigned long address)
{
struct hstate *h = hstate_vma(vma);
struct vm_area_struct *iter_vma;
struct address_space *mapping;
pgoff_t pgoff;
/*
* vm_pgoff is in PAGE_SIZE units, hence the different calculation
* from page cache lookup which is in HPAGE_SIZE units.
*/
address = address & huge_page_mask(h);
pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
vma->vm_pgoff;
mapping = vma->vm_file->f_mapping;
/*
* Take the mapping lock for the duration of the table walk. As
* this mapping should be shared between all the VMAs,
* __unmap_hugepage_range() is called as the lock is already held
*/
i_mmap_lock_write(mapping);
vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
/* Do not unmap the current VMA */
if (iter_vma == vma)
continue;
/*
* Shared VMAs have their own reserves and do not affect
* MAP_PRIVATE accounting but it is possible that a shared
* VMA is using the same page so check and skip such VMAs.
*/
if (iter_vma->vm_flags & VM_MAYSHARE)
continue;
/*
* Unmap the page from other VMAs without their own reserves.
* They get marked to be SIGKILLed if they fault in these
* areas. This is because a future no-page fault on this VMA
* could insert a zeroed page instead of the data existing
* from the time of fork. This would look like data corruption
*/
if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
unmap_hugepage_range(iter_vma, address,
address + huge_page_size(h), page, 0);
}
i_mmap_unlock_write(mapping);
}
/*
* hugetlb_wp() should be called with page lock of the original hugepage held.
* Called with hugetlb_fault_mutex_table held and pte_page locked so we
* cannot race with other handlers or page migration.
* Keep the pte_same checks anyway to make transition from the mutex easier.
*/
static vm_fault_t hugetlb_wp(struct folio *pagecache_folio,
struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
struct mm_struct *mm = vma->vm_mm;
const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
pte_t pte = huge_ptep_get(mm, vmf->address, vmf->pte);
struct hstate *h = hstate_vma(vma);
struct folio *old_folio;
struct folio *new_folio;
int outside_reserve = 0;
vm_fault_t ret = 0;
struct mmu_notifier_range range;
/*
* Never handle CoW for uffd-wp protected pages. It should be only
* handled when the uffd-wp protection is removed.
*
* Note that only the CoW optimization path (in hugetlb_no_page())
* can trigger this, because hugetlb_fault() will always resolve
* uffd-wp bit first.
*/
if (!unshare && huge_pte_uffd_wp(pte))
return 0;
/*
* hugetlb does not support FOLL_FORCE-style write faults that keep the
* PTE mapped R/O such as maybe_mkwrite() would do.
*/
if (WARN_ON_ONCE(!unshare && !(vma->vm_flags & VM_WRITE)))
return VM_FAULT_SIGSEGV;
/* Let's take out MAP_SHARED mappings first. */
if (vma->vm_flags & VM_MAYSHARE) {
set_huge_ptep_writable(vma, vmf->address, vmf->pte);
return 0;
}
old_folio = page_folio(pte_page(pte));
delayacct_wpcopy_start();
retry_avoidcopy:
/*
* If no-one else is actually using this page, we're the exclusive
* owner and can reuse this page.
*
* Note that we don't rely on the (safer) folio refcount here, because
* copying the hugetlb folio when there are unexpected (temporary)
* folio references could harm simple fork()+exit() users when
* we run out of free hugetlb folios: we would have to kill processes
* in scenarios that used to work. As a side effect, there can still
* be leaks between processes, for example, with FOLL_GET users.
*/
if (folio_mapcount(old_folio) == 1 && folio_test_anon(old_folio)) {
if (!PageAnonExclusive(&old_folio->page)) {
folio_move_anon_rmap(old_folio, vma);
SetPageAnonExclusive(&old_folio->page);
}
if (likely(!unshare))
set_huge_ptep_writable(vma, vmf->address, vmf->pte);
delayacct_wpcopy_end();
return 0;
}
VM_BUG_ON_PAGE(folio_test_anon(old_folio) &&
PageAnonExclusive(&old_folio->page), &old_folio->page);
/*
* If the process that created a MAP_PRIVATE mapping is about to
* perform a COW due to a shared page count, attempt to satisfy
* the allocation without using the existing reserves. The pagecache
* page is used to determine if the reserve at this address was
* consumed or not. If reserves were used, a partial faulted mapping
* at the time of fork() could consume its reserves on COW instead
* of the full address range.
*/
if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
old_folio != pagecache_folio)
outside_reserve = 1;
folio_get(old_folio);
/*
* Drop page table lock as buddy allocator may be called. It will
* be acquired again before returning to the caller, as expected.
*/
spin_unlock(vmf->ptl);
new_folio = alloc_hugetlb_folio(vma, vmf->address, outside_reserve);
if (IS_ERR(new_folio)) {
/*
* If a process owning a MAP_PRIVATE mapping fails to COW,
* it is due to references held by a child and an insufficient
* huge page pool. To guarantee the original mappers
* reliability, unmap the page from child processes. The child
* may get SIGKILLed if it later faults.
*/
if (outside_reserve) {
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t idx;
u32 hash;
folio_put(old_folio);
/*
* Drop hugetlb_fault_mutex and vma_lock before
* unmapping. unmapping needs to hold vma_lock
* in write mode. Dropping vma_lock in read mode
* here is OK as COW mappings do not interact with
* PMD sharing.
*
* Reacquire both after unmap operation.
*/
idx = vma_hugecache_offset(h, vma, vmf->address);
hash = hugetlb_fault_mutex_hash(mapping, idx);
hugetlb_vma_unlock_read(vma);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
unmap_ref_private(mm, vma, &old_folio->page,
vmf->address);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
hugetlb_vma_lock_read(vma);
spin_lock(vmf->ptl);
vmf->pte = hugetlb_walk(vma, vmf->address,
huge_page_size(h));
if (likely(vmf->pte &&
pte_same(huge_ptep_get(mm, vmf->address, vmf->pte), pte)))
goto retry_avoidcopy;
/*
* race occurs while re-acquiring page table
* lock, and our job is done.
*/
delayacct_wpcopy_end();
return 0;
}
ret = vmf_error(PTR_ERR(new_folio));
goto out_release_old;
}
/*
* When the original hugepage is shared one, it does not have
* anon_vma prepared.
*/
ret = __vmf_anon_prepare(vmf);
if (unlikely(ret))
goto out_release_all;
if (copy_user_large_folio(new_folio, old_folio, vmf->real_address, vma)) {
ret = VM_FAULT_HWPOISON_LARGE | VM_FAULT_SET_HINDEX(hstate_index(h));
goto out_release_all;
}
__folio_mark_uptodate(new_folio);
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, vmf->address,
vmf->address + huge_page_size(h));
mmu_notifier_invalidate_range_start(&range);
/*
* Retake the page table lock to check for racing updates
* before the page tables are altered
*/
spin_lock(vmf->ptl);
vmf->pte = hugetlb_walk(vma, vmf->address, huge_page_size(h));
if (likely(vmf->pte && pte_same(huge_ptep_get(mm, vmf->address, vmf->pte), pte))) {
pte_t newpte = make_huge_pte(vma, &new_folio->page, !unshare);
/* Break COW or unshare */
huge_ptep_clear_flush(vma, vmf->address, vmf->pte);
hugetlb_remove_rmap(old_folio);
hugetlb_add_new_anon_rmap(new_folio, vma, vmf->address);
if (huge_pte_uffd_wp(pte))
newpte = huge_pte_mkuffd_wp(newpte);
set_huge_pte_at(mm, vmf->address, vmf->pte, newpte,
huge_page_size(h));
folio_set_hugetlb_migratable(new_folio);
/* Make the old page be freed below */
new_folio = old_folio;
}
spin_unlock(vmf->ptl);
mmu_notifier_invalidate_range_end(&range);
out_release_all:
/*
* No restore in case of successful pagetable update (Break COW or
* unshare)
*/
if (new_folio != old_folio)
restore_reserve_on_error(h, vma, vmf->address, new_folio);
folio_put(new_folio);
out_release_old:
folio_put(old_folio);
spin_lock(vmf->ptl); /* Caller expects lock to be held */
delayacct_wpcopy_end();
return ret;
}
/*
* Return whether there is a pagecache page to back given address within VMA.
*/
bool hugetlbfs_pagecache_present(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t idx = linear_page_index(vma, address);
struct folio *folio;
folio = filemap_get_folio(mapping, idx);
if (IS_ERR(folio))
return false;
folio_put(folio);
return true;
}
int hugetlb_add_to_page_cache(struct folio *folio, struct address_space *mapping,
pgoff_t idx)
{
struct inode *inode = mapping->host;
struct hstate *h = hstate_inode(inode);
int err;
idx <<= huge_page_order(h);
__folio_set_locked(folio);
err = __filemap_add_folio(mapping, folio, idx, GFP_KERNEL, NULL);
if (unlikely(err)) {
__folio_clear_locked(folio);
return err;
}
folio_clear_hugetlb_restore_reserve(folio);
/*
* mark folio dirty so that it will not be removed from cache/file
* by non-hugetlbfs specific code paths.
*/
folio_mark_dirty(folio);
spin_lock(&inode->i_lock);
inode->i_blocks += blocks_per_huge_page(h);
spin_unlock(&inode->i_lock);
return 0;
}
static inline vm_fault_t hugetlb_handle_userfault(struct vm_fault *vmf,
struct address_space *mapping,
unsigned long reason)
{
u32 hash;
/*
* vma_lock and hugetlb_fault_mutex must be dropped before handling
* userfault. Also mmap_lock could be dropped due to handling
* userfault, any vma operation should be careful from here.
*/
hugetlb_vma_unlock_read(vmf->vma);
hash = hugetlb_fault_mutex_hash(mapping, vmf->pgoff);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
return handle_userfault(vmf, reason);
}
/*
* Recheck pte with pgtable lock. Returns true if pte didn't change, or
* false if pte changed or is changing.
*/
static bool hugetlb_pte_stable(struct hstate *h, struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t old_pte)
{
spinlock_t *ptl;
bool same;
ptl = huge_pte_lock(h, mm, ptep);
same = pte_same(huge_ptep_get(mm, addr, ptep), old_pte);
spin_unlock(ptl);
return same;
}
static vm_fault_t hugetlb_no_page(struct address_space *mapping,
struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
struct mm_struct *mm = vma->vm_mm;
struct hstate *h = hstate_vma(vma);
vm_fault_t ret = VM_FAULT_SIGBUS;
int anon_rmap = 0;
unsigned long size;
struct folio *folio;
pte_t new_pte;
bool new_folio, new_pagecache_folio = false;
u32 hash = hugetlb_fault_mutex_hash(mapping, vmf->pgoff);
/*
* Currently, we are forced to kill the process in the event the
* original mapper has unmapped pages from the child due to a failed
* COW/unsharing. Warn that such a situation has occurred as it may not
* be obvious.
*/
if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n",
current->pid);
goto out;
}
/*
* Use page lock to guard against racing truncation
* before we get page_table_lock.
*/
new_folio = false;
folio = filemap_lock_hugetlb_folio(h, mapping, vmf->pgoff);
if (IS_ERR(folio)) {
size = i_size_read(mapping->host) >> huge_page_shift(h);
if (vmf->pgoff >= size)
goto out;
/* Check for page in userfault range */
if (userfaultfd_missing(vma)) {
/*
* Since hugetlb_no_page() was examining pte
* without pgtable lock, we need to re-test under
* lock because the pte may not be stable and could
* have changed from under us. Try to detect
* either changed or during-changing ptes and retry
* properly when needed.
*
* Note that userfaultfd is actually fine with
* false positives (e.g. caused by pte changed),
* but not wrong logical events (e.g. caused by
* reading a pte during changing). The latter can
* confuse the userspace, so the strictness is very
* much preferred. E.g., MISSING event should
* never happen on the page after UFFDIO_COPY has
* correctly installed the page and returned.
*/
if (!hugetlb_pte_stable(h, mm, vmf->address, vmf->pte, vmf->orig_pte)) {
ret = 0;
goto out;
}
return hugetlb_handle_userfault(vmf, mapping,
VM_UFFD_MISSING);
}
if (!(vma->vm_flags & VM_MAYSHARE)) {
ret = __vmf_anon_prepare(vmf);
if (unlikely(ret))
goto out;
}
folio = alloc_hugetlb_folio(vma, vmf->address, 0);
if (IS_ERR(folio)) {
/*
* Returning error will result in faulting task being
* sent SIGBUS. The hugetlb fault mutex prevents two
* tasks from racing to fault in the same page which
* could result in false unable to allocate errors.
* Page migration does not take the fault mutex, but
* does a clear then write of pte's under page table
* lock. Page fault code could race with migration,
* notice the clear pte and try to allocate a page
* here. Before returning error, get ptl and make
* sure there really is no pte entry.
*/
if (hugetlb_pte_stable(h, mm, vmf->address, vmf->pte, vmf->orig_pte))
ret = vmf_error(PTR_ERR(folio));
else
ret = 0;
goto out;
}
folio_zero_user(folio, vmf->real_address);
__folio_mark_uptodate(folio);
new_folio = true;
if (vma->vm_flags & VM_MAYSHARE) {
int err = hugetlb_add_to_page_cache(folio, mapping,
vmf->pgoff);
if (err) {
/*
* err can't be -EEXIST which implies someone
* else consumed the reservation since hugetlb
* fault mutex is held when add a hugetlb page
* to the page cache. So it's safe to call
* restore_reserve_on_error() here.
*/
restore_reserve_on_error(h, vma, vmf->address,
folio);
folio_put(folio);
ret = VM_FAULT_SIGBUS;
goto out;
}
new_pagecache_folio = true;
} else {
folio_lock(folio);
anon_rmap = 1;
}
} else {
/*
* If memory error occurs between mmap() and fault, some process
* don't have hwpoisoned swap entry for errored virtual address.
* So we need to block hugepage fault by PG_hwpoison bit check.
*/
if (unlikely(folio_test_hwpoison(folio))) {
ret = VM_FAULT_HWPOISON_LARGE |
VM_FAULT_SET_HINDEX(hstate_index(h));
goto backout_unlocked;
}
/* Check for page in userfault range. */
if (userfaultfd_minor(vma)) {
folio_unlock(folio);
folio_put(folio);
/* See comment in userfaultfd_missing() block above */
if (!hugetlb_pte_stable(h, mm, vmf->address, vmf->pte, vmf->orig_pte)) {
ret = 0;
goto out;
}
return hugetlb_handle_userfault(vmf, mapping,
VM_UFFD_MINOR);
}
}
/*
* If we are going to COW a private mapping later, we examine the
* pending reservations for this page now. This will ensure that
* any allocations necessary to record that reservation occur outside
* the spinlock.
*/
if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
if (vma_needs_reservation(h, vma, vmf->address) < 0) {
ret = VM_FAULT_OOM;
goto backout_unlocked;
}
/* Just decrements count, does not deallocate */
vma_end_reservation(h, vma, vmf->address);
}
vmf->ptl = huge_pte_lock(h, mm, vmf->pte);
ret = 0;
/* If pte changed from under us, retry */
if (!pte_same(huge_ptep_get(mm, vmf->address, vmf->pte), vmf->orig_pte))
goto backout;
if (anon_rmap)
hugetlb_add_new_anon_rmap(folio, vma, vmf->address);
else
hugetlb_add_file_rmap(folio);
new_pte = make_huge_pte(vma, &folio->page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
/*
* If this pte was previously wr-protected, keep it wr-protected even
* if populated.
*/
if (unlikely(pte_marker_uffd_wp(vmf->orig_pte)))
new_pte = huge_pte_mkuffd_wp(new_pte);
set_huge_pte_at(mm, vmf->address, vmf->pte, new_pte, huge_page_size(h));
hugetlb_count_add(pages_per_huge_page(h), mm);
if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
/* Optimization, do the COW without a second fault */
ret = hugetlb_wp(folio, vmf);
}
spin_unlock(vmf->ptl);
/*
* Only set hugetlb_migratable in newly allocated pages. Existing pages
* found in the pagecache may not have hugetlb_migratable if they have
* been isolated for migration.
*/
if (new_folio)
folio_set_hugetlb_migratable(folio);
folio_unlock(folio);
out:
hugetlb_vma_unlock_read(vma);
/*
* We must check to release the per-VMA lock. __vmf_anon_prepare() is
* the only way ret can be set to VM_FAULT_RETRY.
*/
if (unlikely(ret & VM_FAULT_RETRY))
vma_end_read(vma);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
return ret;
backout:
spin_unlock(vmf->ptl);
backout_unlocked:
if (new_folio && !new_pagecache_folio)
restore_reserve_on_error(h, vma, vmf->address, folio);
folio_unlock(folio);
folio_put(folio);
goto out;
}
#ifdef CONFIG_SMP
u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx)
{
unsigned long key[2];
u32 hash;
key[0] = (unsigned long) mapping;
key[1] = idx;
hash = jhash2((u32 *)&key, sizeof(key)/(sizeof(u32)), 0);
return hash & (num_fault_mutexes - 1);
}
#else
/*
* For uniprocessor systems we always use a single mutex, so just
* return 0 and avoid the hashing overhead.
*/
u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx)
{
return 0;
}
#endif
vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
{
vm_fault_t ret;
u32 hash;
struct folio *folio = NULL;
struct folio *pagecache_folio = NULL;
struct hstate *h = hstate_vma(vma);
struct address_space *mapping;
int need_wait_lock = 0;
struct vm_fault vmf = {
.vma = vma,
.address = address & huge_page_mask(h),
.real_address = address,
.flags = flags,
.pgoff = vma_hugecache_offset(h, vma,
address & huge_page_mask(h)),
/* TODO: Track hugetlb faults using vm_fault */
/*
* Some fields may not be initialized, be careful as it may
* be hard to debug if called functions make assumptions
*/
};
/*
* Serialize hugepage allocation and instantiation, so that we don't
* get spurious allocation failures if two CPUs race to instantiate
* the same page in the page cache.
*/
mapping = vma->vm_file->f_mapping;
hash = hugetlb_fault_mutex_hash(mapping, vmf.pgoff);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
/*
* Acquire vma lock before calling huge_pte_alloc and hold
* until finished with vmf.pte. This prevents huge_pmd_unshare from
* being called elsewhere and making the vmf.pte no longer valid.
*/
hugetlb_vma_lock_read(vma);
vmf.pte = huge_pte_alloc(mm, vma, vmf.address, huge_page_size(h));
if (!vmf.pte) {
hugetlb_vma_unlock_read(vma);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
return VM_FAULT_OOM;
}
vmf.orig_pte = huge_ptep_get(mm, vmf.address, vmf.pte);
if (huge_pte_none_mostly(vmf.orig_pte)) {
if (is_pte_marker(vmf.orig_pte)) {
pte_marker marker =
pte_marker_get(pte_to_swp_entry(vmf.orig_pte));
if (marker & PTE_MARKER_POISONED) {
ret = VM_FAULT_HWPOISON_LARGE |
VM_FAULT_SET_HINDEX(hstate_index(h));
goto out_mutex;
}
}
/*
* Other PTE markers should be handled the same way as none PTE.
*
* hugetlb_no_page will drop vma lock and hugetlb fault
* mutex internally, which make us return immediately.
*/
return hugetlb_no_page(mapping, &vmf);
}
ret = 0;
/*
* vmf.orig_pte could be a migration/hwpoison vmf.orig_pte at this
* point, so this check prevents the kernel from going below assuming
* that we have an active hugepage in pagecache. This goto expects
* the 2nd page fault, and is_hugetlb_entry_(migration|hwpoisoned)
* check will properly handle it.
*/
if (!pte_present(vmf.orig_pte)) {
if (unlikely(is_hugetlb_entry_migration(vmf.orig_pte))) {
/*
* Release the hugetlb fault lock now, but retain
* the vma lock, because it is needed to guard the
* huge_pte_lockptr() later in
* migration_entry_wait_huge(). The vma lock will
* be released there.
*/
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
migration_entry_wait_huge(vma, vmf.address, vmf.pte);
return 0;
} else if (unlikely(is_hugetlb_entry_hwpoisoned(vmf.orig_pte)))
ret = VM_FAULT_HWPOISON_LARGE |
VM_FAULT_SET_HINDEX(hstate_index(h));
goto out_mutex;
}
/*
* If we are going to COW/unshare the mapping later, we examine the
* pending reservations for this page now. This will ensure that any
* allocations necessary to record that reservation occur outside the
* spinlock. Also lookup the pagecache page now as it is used to
* determine if a reservation has been consumed.
*/
if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
!(vma->vm_flags & VM_MAYSHARE) && !huge_pte_write(vmf.orig_pte)) {
if (vma_needs_reservation(h, vma, vmf.address) < 0) {
ret = VM_FAULT_OOM;
goto out_mutex;
}
/* Just decrements count, does not deallocate */
vma_end_reservation(h, vma, vmf.address);
pagecache_folio = filemap_lock_hugetlb_folio(h, mapping,
vmf.pgoff);
if (IS_ERR(pagecache_folio))
pagecache_folio = NULL;
}
vmf.ptl = huge_pte_lock(h, mm, vmf.pte);
/* Check for a racing update before calling hugetlb_wp() */
if (unlikely(!pte_same(vmf.orig_pte, huge_ptep_get(mm, vmf.address, vmf.pte))))
goto out_ptl;
/* Handle userfault-wp first, before trying to lock more pages */
if (userfaultfd_wp(vma) && huge_pte_uffd_wp(huge_ptep_get(mm, vmf.address, vmf.pte)) &&
(flags & FAULT_FLAG_WRITE) && !huge_pte_write(vmf.orig_pte)) {
if (!userfaultfd_wp_async(vma)) {
spin_unlock(vmf.ptl);
if (pagecache_folio) {
folio_unlock(pagecache_folio);
folio_put(pagecache_folio);
}
hugetlb_vma_unlock_read(vma);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
return handle_userfault(&vmf, VM_UFFD_WP);
}
vmf.orig_pte = huge_pte_clear_uffd_wp(vmf.orig_pte);
set_huge_pte_at(mm, vmf.address, vmf.pte, vmf.orig_pte,
huge_page_size(hstate_vma(vma)));
/* Fallthrough to CoW */
}
/*
* hugetlb_wp() requires page locks of pte_page(vmf.orig_pte) and
* pagecache_folio, so here we need take the former one
* when folio != pagecache_folio or !pagecache_folio.
*/
folio = page_folio(pte_page(vmf.orig_pte));
if (folio != pagecache_folio)
if (!folio_trylock(folio)) {
need_wait_lock = 1;
goto out_ptl;
}
folio_get(folio);
if (flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
if (!huge_pte_write(vmf.orig_pte)) {
ret = hugetlb_wp(pagecache_folio, &vmf);
goto out_put_page;
} else if (likely(flags & FAULT_FLAG_WRITE)) {
vmf.orig_pte = huge_pte_mkdirty(vmf.orig_pte);
}
}
vmf.orig_pte = pte_mkyoung(vmf.orig_pte);
if (huge_ptep_set_access_flags(vma, vmf.address, vmf.pte, vmf.orig_pte,
flags & FAULT_FLAG_WRITE))
update_mmu_cache(vma, vmf.address, vmf.pte);
out_put_page:
if (folio != pagecache_folio)
folio_unlock(folio);
folio_put(folio);
out_ptl:
spin_unlock(vmf.ptl);
if (pagecache_folio) {
folio_unlock(pagecache_folio);
folio_put(pagecache_folio);
}
out_mutex:
hugetlb_vma_unlock_read(vma);
/*
* We must check to release the per-VMA lock. __vmf_anon_prepare() in
* hugetlb_wp() is the only way ret can be set to VM_FAULT_RETRY.
*/
if (unlikely(ret & VM_FAULT_RETRY))
vma_end_read(vma);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
/*
* Generally it's safe to hold refcount during waiting page lock. But
* here we just wait to defer the next page fault to avoid busy loop and
* the page is not used after unlocked before returning from the current
* page fault. So we are safe from accessing freed page, even if we wait
* here without taking refcount.
*/
if (need_wait_lock)
folio_wait_locked(folio);
return ret;
}
#ifdef CONFIG_USERFAULTFD
/*
* Can probably be eliminated, but still used by hugetlb_mfill_atomic_pte().
*/
static struct folio *alloc_hugetlb_folio_vma(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
struct mempolicy *mpol;
nodemask_t *nodemask;
struct folio *folio;
gfp_t gfp_mask;
int node;
gfp_mask = htlb_alloc_mask(h);
node = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
/*
* This is used to allocate a temporary hugetlb to hold the copied
* content, which will then be copied again to the final hugetlb
* consuming a reservation. Set the alloc_fallback to false to indicate
* that breaking the per-node hugetlb pool is not allowed in this case.
*/
folio = alloc_hugetlb_folio_nodemask(h, node, nodemask, gfp_mask, false);
mpol_cond_put(mpol);
return folio;
}
/*
* Used by userfaultfd UFFDIO_* ioctls. Based on userfaultfd's mfill_atomic_pte
* with modifications for hugetlb pages.
*/
int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
uffd_flags_t flags,
struct folio **foliop)
{
struct mm_struct *dst_mm = dst_vma->vm_mm;
bool is_continue = uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE);
bool wp_enabled = (flags & MFILL_ATOMIC_WP);
struct hstate *h = hstate_vma(dst_vma);
struct address_space *mapping = dst_vma->vm_file->f_mapping;
pgoff_t idx = vma_hugecache_offset(h, dst_vma, dst_addr);
unsigned long size = huge_page_size(h);
int vm_shared = dst_vma->vm_flags & VM_SHARED;
pte_t _dst_pte;
spinlock_t *ptl;
int ret = -ENOMEM;
struct folio *folio;
int writable;
bool folio_in_pagecache = false;
if (uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) {
ptl = huge_pte_lock(h, dst_mm, dst_pte);
/* Don't overwrite any existing PTEs (even markers) */
if (!huge_pte_none(huge_ptep_get(dst_mm, dst_addr, dst_pte))) {
spin_unlock(ptl);
return -EEXIST;
}
_dst_pte = make_pte_marker(PTE_MARKER_POISONED);
set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte, size);
/* No need to invalidate - it was non-present before */
update_mmu_cache(dst_vma, dst_addr, dst_pte);
spin_unlock(ptl);
return 0;
}
if (is_continue) {
ret = -EFAULT;
folio = filemap_lock_hugetlb_folio(h, mapping, idx);
if (IS_ERR(folio))
goto out;
folio_in_pagecache = true;
} else if (!*foliop) {
/* If a folio already exists, then it's UFFDIO_COPY for
* a non-missing case. Return -EEXIST.
*/
if (vm_shared &&
hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) {
ret = -EEXIST;
goto out;
}
folio = alloc_hugetlb_folio(dst_vma, dst_addr, 0);
if (IS_ERR(folio)) {
ret = -ENOMEM;
goto out;
}
ret = copy_folio_from_user(folio, (const void __user *) src_addr,
false);
/* fallback to copy_from_user outside mmap_lock */
if (unlikely(ret)) {
ret = -ENOENT;
/* Free the allocated folio which may have
* consumed a reservation.
*/
restore_reserve_on_error(h, dst_vma, dst_addr, folio);
folio_put(folio);
/* Allocate a temporary folio to hold the copied
* contents.
*/
folio = alloc_hugetlb_folio_vma(h, dst_vma, dst_addr);
if (!folio) {
ret = -ENOMEM;
goto out;
}
*foliop = folio;
/* Set the outparam foliop and return to the caller to
* copy the contents outside the lock. Don't free the
* folio.
*/
goto out;
}
} else {
if (vm_shared &&
hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) {
folio_put(*foliop);
ret = -EEXIST;
*foliop = NULL;
goto out;
}
folio = alloc_hugetlb_folio(dst_vma, dst_addr, 0);
if (IS_ERR(folio)) {
folio_put(*foliop);
ret = -ENOMEM;
*foliop = NULL;
goto out;
}
ret = copy_user_large_folio(folio, *foliop,
ALIGN_DOWN(dst_addr, size), dst_vma);
folio_put(*foliop);
*foliop = NULL;
if (ret) {
folio_put(folio);
goto out;
}
}
/*
* If we just allocated a new page, we need a memory barrier to ensure
* that preceding stores to the page become visible before the
* set_pte_at() write. The memory barrier inside __folio_mark_uptodate
* is what we need.
*
* In the case where we have not allocated a new page (is_continue),
* the page must already be uptodate. UFFDIO_CONTINUE already includes
* an earlier smp_wmb() to ensure that prior stores will be visible
* before the set_pte_at() write.
*/
if (!is_continue)
__folio_mark_uptodate(folio);
else
WARN_ON_ONCE(!folio_test_uptodate(folio));
/* Add shared, newly allocated pages to the page cache. */
if (vm_shared && !is_continue) {
ret = -EFAULT;
if (idx >= (i_size_read(mapping->host) >> huge_page_shift(h)))
goto out_release_nounlock;
/*
* Serialization between remove_inode_hugepages() and
* hugetlb_add_to_page_cache() below happens through the
* hugetlb_fault_mutex_table that here must be hold by
* the caller.
*/
ret = hugetlb_add_to_page_cache(folio, mapping, idx);
if (ret)
goto out_release_nounlock;
folio_in_pagecache = true;
}
ptl = huge_pte_lock(h, dst_mm, dst_pte);
ret = -EIO;
if (folio_test_hwpoison(folio))
goto out_release_unlock;
/*
* We allow to overwrite a pte marker: consider when both MISSING|WP
* registered, we firstly wr-protect a none pte which has no page cache
* page backing it, then access the page.
*/
ret = -EEXIST;
if (!huge_pte_none_mostly(huge_ptep_get(dst_mm, dst_addr, dst_pte)))
goto out_release_unlock;
if (folio_in_pagecache)
hugetlb_add_file_rmap(folio);
else
hugetlb_add_new_anon_rmap(folio, dst_vma, dst_addr);
/*
* For either: (1) CONTINUE on a non-shared VMA, or (2) UFFDIO_COPY
* with wp flag set, don't set pte write bit.
*/
if (wp_enabled || (is_continue && !vm_shared))
writable = 0;
else
writable = dst_vma->vm_flags & VM_WRITE;
_dst_pte = make_huge_pte(dst_vma, &folio->page, writable);
/*
* Always mark UFFDIO_COPY page dirty; note that this may not be
* extremely important for hugetlbfs for now since swapping is not
* supported, but we should still be clear in that this page cannot be
* thrown away at will, even if write bit not set.
*/
_dst_pte = huge_pte_mkdirty(_dst_pte);
_dst_pte = pte_mkyoung(_dst_pte);
if (wp_enabled)
_dst_pte = huge_pte_mkuffd_wp(_dst_pte);
set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte, size);
hugetlb_count_add(pages_per_huge_page(h), dst_mm);
/* No need to invalidate - it was non-present before */
update_mmu_cache(dst_vma, dst_addr, dst_pte);
spin_unlock(ptl);
if (!is_continue)
folio_set_hugetlb_migratable(folio);
if (vm_shared || is_continue)
folio_unlock(folio);
ret = 0;
out:
return ret;
out_release_unlock:
spin_unlock(ptl);
if (vm_shared || is_continue)
folio_unlock(folio);
out_release_nounlock:
if (!folio_in_pagecache)
restore_reserve_on_error(h, dst_vma, dst_addr, folio);
folio_put(folio);
goto out;
}
#endif /* CONFIG_USERFAULTFD */
long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end,
pgprot_t newprot, unsigned long cp_flags)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long start = address;
pte_t *ptep;
pte_t pte;
struct hstate *h = hstate_vma(vma);
long pages = 0, psize = huge_page_size(h);
bool shared_pmd = false;
struct mmu_notifier_range range;
unsigned long last_addr_mask;
bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
/*
* In the case of shared PMDs, the area to flush could be beyond
* start/end. Set range.start/range.end to cover the maximum possible
* range if PMD sharing is possible.
*/
mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA,
0, mm, start, end);
adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
BUG_ON(address >= end);
flush_cache_range(vma, range.start, range.end);
mmu_notifier_invalidate_range_start(&range);
hugetlb_vma_lock_write(vma);
i_mmap_lock_write(vma->vm_file->f_mapping);
last_addr_mask = hugetlb_mask_last_page(h);
for (; address < end; address += psize) {
spinlock_t *ptl;
ptep = hugetlb_walk(vma, address, psize);
if (!ptep) {
if (!uffd_wp) {
address |= last_addr_mask;
continue;
}
/*
* Userfaultfd wr-protect requires pgtable
* pre-allocations to install pte markers.
*/
ptep = huge_pte_alloc(mm, vma, address, psize);
if (!ptep) {
pages = -ENOMEM;
break;
}
}
ptl = huge_pte_lock(h, mm, ptep);
if (huge_pmd_unshare(mm, vma, address, ptep)) {
/*
* When uffd-wp is enabled on the vma, unshare
* shouldn't happen at all. Warn about it if it
* happened due to some reason.
*/
WARN_ON_ONCE(uffd_wp || uffd_wp_resolve);
pages++;
spin_unlock(ptl);
shared_pmd = true;
address |= last_addr_mask;
continue;
}
pte = huge_ptep_get(mm, address, ptep);
if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
/* Nothing to do. */
} else if (unlikely(is_hugetlb_entry_migration(pte))) {
swp_entry_t entry = pte_to_swp_entry(pte);
struct page *page = pfn_swap_entry_to_page(entry);
pte_t newpte = pte;
if (is_writable_migration_entry(entry)) {
if (PageAnon(page))
entry = make_readable_exclusive_migration_entry(
swp_offset(entry));
else
entry = make_readable_migration_entry(
swp_offset(entry));
newpte = swp_entry_to_pte(entry);
pages++;
}
if (uffd_wp)
newpte = pte_swp_mkuffd_wp(newpte);
else if (uffd_wp_resolve)
newpte = pte_swp_clear_uffd_wp(newpte);
if (!pte_same(pte, newpte))
set_huge_pte_at(mm, address, ptep, newpte, psize);
} else if (unlikely(is_pte_marker(pte))) {
/*
* Do nothing on a poison marker; page is
* corrupted, permissons do not apply. Here
* pte_marker_uffd_wp()==true implies !poison
* because they're mutual exclusive.
*/
if (pte_marker_uffd_wp(pte) && uffd_wp_resolve)
/* Safe to modify directly (non-present->none). */
huge_pte_clear(mm, address, ptep, psize);
} else if (!huge_pte_none(pte)) {
pte_t old_pte;
unsigned int shift = huge_page_shift(hstate_vma(vma));
old_pte = huge_ptep_modify_prot_start(vma, address, ptep);
pte = huge_pte_modify(old_pte, newprot);
pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
if (uffd_wp)
pte = huge_pte_mkuffd_wp(pte);
else if (uffd_wp_resolve)
pte = huge_pte_clear_uffd_wp(pte);
huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte);
pages++;
} else {
/* None pte */
if (unlikely(uffd_wp))
/* Safe to modify directly (none->non-present). */
set_huge_pte_at(mm, address, ptep,
make_pte_marker(PTE_MARKER_UFFD_WP),
psize);
}
spin_unlock(ptl);
}
/*
* Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
* may have cleared our pud entry and done put_page on the page table:
* once we release i_mmap_rwsem, another task can do the final put_page
* and that page table be reused and filled with junk. If we actually
* did unshare a page of pmds, flush the range corresponding to the pud.
*/
if (shared_pmd)
flush_hugetlb_tlb_range(vma, range.start, range.end);
else
flush_hugetlb_tlb_range(vma, start, end);
/*
* No need to call mmu_notifier_arch_invalidate_secondary_tlbs() we are
* downgrading page table protection not changing it to point to a new
* page.
*
* See Documentation/mm/mmu_notifier.rst
*/
i_mmap_unlock_write(vma->vm_file->f_mapping);
hugetlb_vma_unlock_write(vma);
mmu_notifier_invalidate_range_end(&range);
return pages > 0 ? (pages << h->order) : pages;
}
/* Return true if reservation was successful, false otherwise. */
bool hugetlb_reserve_pages(struct inode *inode,
long from, long to,
struct vm_area_struct *vma,
vm_flags_t vm_flags)
{
long chg = -1, add = -1;
struct hstate *h = hstate_inode(inode);
struct hugepage_subpool *spool = subpool_inode(inode);
struct resv_map *resv_map;
struct hugetlb_cgroup *h_cg = NULL;
long gbl_reserve, regions_needed = 0;
/* This should never happen */
if (from > to) {
VM_WARN(1, "%s called with a negative range\n", __func__);
return false;
}
/*
* vma specific semaphore used for pmd sharing and fault/truncation
* synchronization
*/
hugetlb_vma_lock_alloc(vma);
/*
* Only apply hugepage reservation if asked. At fault time, an
* attempt will be made for VM_NORESERVE to allocate a page
* without using reserves
*/
if (vm_flags & VM_NORESERVE)
return true;
/*
* Shared mappings base their reservation on the number of pages that
* are already allocated on behalf of the file. Private mappings need
* to reserve the full area even if read-only as mprotect() may be
* called to make the mapping read-write. Assume !vma is a shm mapping
*/
if (!vma || vma->vm_flags & VM_MAYSHARE) {
/*
* resv_map can not be NULL as hugetlb_reserve_pages is only
* called for inodes for which resv_maps were created (see
* hugetlbfs_get_inode).
*/
resv_map = inode_resv_map(inode);
chg = region_chg(resv_map, from, to, &regions_needed);
} else {
/* Private mapping. */
resv_map = resv_map_alloc();
if (!resv_map)
goto out_err;
chg = to - from;
set_vma_resv_map(vma, resv_map);
set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
}
if (chg < 0)
goto out_err;
if (hugetlb_cgroup_charge_cgroup_rsvd(hstate_index(h),
chg * pages_per_huge_page(h), &h_cg) < 0)
goto out_err;
if (vma && !(vma->vm_flags & VM_MAYSHARE) && h_cg) {
/* For private mappings, the hugetlb_cgroup uncharge info hangs
* of the resv_map.
*/
resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, h_cg, h);
}
/*
* There must be enough pages in the subpool for the mapping. If
* the subpool has a minimum size, there may be some global
* reservations already in place (gbl_reserve).
*/
gbl_reserve = hugepage_subpool_get_pages(spool, chg);
if (gbl_reserve < 0)
goto out_uncharge_cgroup;
/*
* Check enough hugepages are available for the reservation.
* Hand the pages back to the subpool if there are not
*/
if (hugetlb_acct_memory(h, gbl_reserve) < 0)
goto out_put_pages;
/*
* Account for the reservations made. Shared mappings record regions
* that have reservations as they are shared by multiple VMAs.
* When the last VMA disappears, the region map says how much
* the reservation was and the page cache tells how much of
* the reservation was consumed. Private mappings are per-VMA and
* only the consumed reservations are tracked. When the VMA
* disappears, the original reservation is the VMA size and the
* consumed reservations are stored in the map. Hence, nothing
* else has to be done for private mappings here
*/
if (!vma || vma->vm_flags & VM_MAYSHARE) {
add = region_add(resv_map, from, to, regions_needed, h, h_cg);
if (unlikely(add < 0)) {
hugetlb_acct_memory(h, -gbl_reserve);
goto out_put_pages;
} else if (unlikely(chg > add)) {
/*
* pages in this range were added to the reserve
* map between region_chg and region_add. This
* indicates a race with alloc_hugetlb_folio. Adjust
* the subpool and reserve counts modified above
* based on the difference.
*/
long rsv_adjust;
/*
* hugetlb_cgroup_uncharge_cgroup_rsvd() will put the
* reference to h_cg->css. See comment below for detail.
*/
hugetlb_cgroup_uncharge_cgroup_rsvd(
hstate_index(h),
(chg - add) * pages_per_huge_page(h), h_cg);
rsv_adjust = hugepage_subpool_put_pages(spool,
chg - add);
hugetlb_acct_memory(h, -rsv_adjust);
} else if (h_cg) {
/*
* The file_regions will hold their own reference to
* h_cg->css. So we should release the reference held
* via hugetlb_cgroup_charge_cgroup_rsvd() when we are
* done.
*/
hugetlb_cgroup_put_rsvd_cgroup(h_cg);
}
}
return true;
out_put_pages:
/* put back original number of pages, chg */
(void)hugepage_subpool_put_pages(spool, chg);
out_uncharge_cgroup:
hugetlb_cgroup_uncharge_cgroup_rsvd(hstate_index(h),
chg * pages_per_huge_page(h), h_cg);
out_err:
hugetlb_vma_lock_free(vma);
if (!vma || vma->vm_flags & VM_MAYSHARE)
/* Only call region_abort if the region_chg succeeded but the
* region_add failed or didn't run.
*/
if (chg >= 0 && add < 0)
region_abort(resv_map, from, to, regions_needed);
if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
kref_put(&resv_map->refs, resv_map_release);
set_vma_resv_map(vma, NULL);
}
return false;
}
long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
long freed)
{
struct hstate *h = hstate_inode(inode);
struct resv_map *resv_map = inode_resv_map(inode);
long chg = 0;
struct hugepage_subpool *spool = subpool_inode(inode);
long gbl_reserve;
/*
* Since this routine can be called in the evict inode path for all
* hugetlbfs inodes, resv_map could be NULL.
*/
if (resv_map) {
chg = region_del(resv_map, start, end);
/*
* region_del() can fail in the rare case where a region
* must be split and another region descriptor can not be
* allocated. If end == LONG_MAX, it will not fail.
*/
if (chg < 0)
return chg;
}
spin_lock(&inode->i_lock);
inode->i_blocks -= (blocks_per_huge_page(h) * freed);
spin_unlock(&inode->i_lock);
/*
* If the subpool has a minimum size, the number of global
* reservations to be released may be adjusted.
*
* Note that !resv_map implies freed == 0. So (chg - freed)
* won't go negative.
*/
gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
hugetlb_acct_memory(h, -gbl_reserve);
return 0;
}
#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
static unsigned long page_table_shareable(struct vm_area_struct *svma,
struct vm_area_struct *vma,
unsigned long addr, pgoff_t idx)
{
unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
svma->vm_start;
unsigned long sbase = saddr & PUD_MASK;
unsigned long s_end = sbase + PUD_SIZE;
/* Allow segments to share if only one is marked locked */
unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED_MASK;
unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED_MASK;
/*
* match the virtual addresses, permission and the alignment of the
* page table page.
*
* Also, vma_lock (vm_private_data) is required for sharing.
*/
if (pmd_index(addr) != pmd_index(saddr) ||
vm_flags != svm_flags ||
!range_in_vma(svma, sbase, s_end) ||
!svma->vm_private_data)
return 0;
return saddr;
}
bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr)
{
unsigned long start = addr & PUD_MASK;
unsigned long end = start + PUD_SIZE;
#ifdef CONFIG_USERFAULTFD
if (uffd_disable_huge_pmd_share(vma))
return false;
#endif
/*
* check on proper vm_flags and page table alignment
*/
if (!(vma->vm_flags & VM_MAYSHARE))
return false;
if (!vma->vm_private_data) /* vma lock required for sharing */
return false;
if (!range_in_vma(vma, start, end))
return false;
return true;
}
/*
* Determine if start,end range within vma could be mapped by shared pmd.
* If yes, adjust start and end to cover range associated with possible
* shared pmd mappings.
*/
void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
unsigned long *start, unsigned long *end)
{
unsigned long v_start = ALIGN(vma->vm_start, PUD_SIZE),
v_end = ALIGN_DOWN(vma->vm_end, PUD_SIZE);
/*
* vma needs to span at least one aligned PUD size, and the range
* must be at least partially within in.
*/
if (!(vma->vm_flags & VM_MAYSHARE) || !(v_end > v_start) ||
(*end <= v_start) || (*start >= v_end))
return;
/* Extend the range to be PUD aligned for a worst case scenario */
if (*start > v_start)
*start = ALIGN_DOWN(*start, PUD_SIZE);
if (*end < v_end)
*end = ALIGN(*end, PUD_SIZE);
}
/*
* Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
* and returns the corresponding pte. While this is not necessary for the
* !shared pmd case because we can allocate the pmd later as well, it makes the
* code much cleaner. pmd allocation is essential for the shared case because
* pud has to be populated inside the same i_mmap_rwsem section - otherwise
* racing tasks could either miss the sharing (see huge_pte_offset) or select a
* bad pmd for sharing.
*/
pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pud_t *pud)
{
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
vma->vm_pgoff;
struct vm_area_struct *svma;
unsigned long saddr;
pte_t *spte = NULL;
pte_t *pte;
i_mmap_lock_read(mapping);
vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
if (svma == vma)
continue;
saddr = page_table_shareable(svma, vma, addr, idx);
if (saddr) {
spte = hugetlb_walk(svma, saddr,
vma_mmu_pagesize(svma));
if (spte) {
get_page(virt_to_page(spte));
break;
}
}
}
if (!spte)
goto out;
spin_lock(&mm->page_table_lock);
if (pud_none(*pud)) {
pud_populate(mm, pud,
(pmd_t *)((unsigned long)spte & PAGE_MASK));
mm_inc_nr_pmds(mm);
} else {
put_page(virt_to_page(spte));
}
spin_unlock(&mm->page_table_lock);
out:
pte = (pte_t *)pmd_alloc(mm, pud, addr);
i_mmap_unlock_read(mapping);
return pte;
}
/*
* unmap huge page backed by shared pte.
*
* Hugetlb pte page is ref counted at the time of mapping. If pte is shared
* indicated by page_count > 1, unmap is achieved by clearing pud and
* decrementing the ref count. If count == 1, the pte page is not shared.
*
* Called with page table lock held.
*
* returns: 1 successfully unmapped a shared pte page
* 0 the underlying pte page is not shared, or it is the last user
*/
int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
pgd_t *pgd = pgd_offset(mm, addr);
p4d_t *p4d = p4d_offset(pgd, addr);
pud_t *pud = pud_offset(p4d, addr);
i_mmap_assert_write_locked(vma->vm_file->f_mapping);
hugetlb_vma_assert_locked(vma);
BUG_ON(page_count(virt_to_page(ptep)) == 0);
if (page_count(virt_to_page(ptep)) == 1)
return 0;
pud_clear(pud);
put_page(virt_to_page(ptep));
mm_dec_nr_pmds(mm);
return 1;
}
#else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pud_t *pud)
{
return NULL;
}
int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
return 0;
}
void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
unsigned long *start, unsigned long *end)
{
}
bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr)
{
return false;
}
#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long sz)
{
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pte_t *pte = NULL;
pgd = pgd_offset(mm, addr);
p4d = p4d_alloc(mm, pgd, addr);
if (!p4d)
return NULL;
pud = pud_alloc(mm, p4d, addr);
if (pud) {
if (sz == PUD_SIZE) {
pte = (pte_t *)pud;
} else {
BUG_ON(sz != PMD_SIZE);
if (want_pmd_share(vma, addr) && pud_none(*pud))
pte = huge_pmd_share(mm, vma, addr, pud);
else
pte = (pte_t *)pmd_alloc(mm, pud, addr);
}
}
if (pte) {
pte_t pteval = ptep_get_lockless(pte);
BUG_ON(pte_present(pteval) && !pte_huge(pteval));
}
return pte;
}
/*
* huge_pte_offset() - Walk the page table to resolve the hugepage
* entry at address @addr
*
* Return: Pointer to page table entry (PUD or PMD) for
* address @addr, or NULL if a !p*d_present() entry is encountered and the
* size @sz doesn't match the hugepage size at this level of the page
* table.
*/
pte_t *huge_pte_offset(struct mm_struct *mm,
unsigned long addr, unsigned long sz)
{
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
pgd = pgd_offset(mm, addr);
if (!pgd_present(*pgd))
return NULL;
p4d = p4d_offset(pgd, addr);
if (!p4d_present(*p4d))
return NULL;
pud = pud_offset(p4d, addr);
if (sz == PUD_SIZE)
/* must be pud huge, non-present or none */
return (pte_t *)pud;
if (!pud_present(*pud))
return NULL;
/* must have a valid entry and size to go further */
pmd = pmd_offset(pud, addr);
/* must be pmd huge, non-present or none */
return (pte_t *)pmd;
}
/*
* Return a mask that can be used to update an address to the last huge
* page in a page table page mapping size. Used to skip non-present
* page table entries when linearly scanning address ranges. Architectures
* with unique huge page to page table relationships can define their own
* version of this routine.
*/
unsigned long hugetlb_mask_last_page(struct hstate *h)
{
unsigned long hp_size = huge_page_size(h);
if (hp_size == PUD_SIZE)
return P4D_SIZE - PUD_SIZE;
else if (hp_size == PMD_SIZE)
return PUD_SIZE - PMD_SIZE;
else
return 0UL;
}
#else
/* See description above. Architectures can provide their own version. */
__weak unsigned long hugetlb_mask_last_page(struct hstate *h)
{
#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
if (huge_page_size(h) == PMD_SIZE)
return PUD_SIZE - PMD_SIZE;
#endif
return 0UL;
}
#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
/*
* These functions are overwritable if your architecture needs its own
* behavior.
*/
bool isolate_hugetlb(struct folio *folio, struct list_head *list)
{
bool ret = true;
spin_lock_irq(&hugetlb_lock);
if (!folio_test_hugetlb(folio) ||
!folio_test_hugetlb_migratable(folio) ||
!folio_try_get(folio)) {
ret = false;
goto unlock;
}
folio_clear_hugetlb_migratable(folio);
list_move_tail(&folio->lru, list);
unlock:
spin_unlock_irq(&hugetlb_lock);
return ret;
}
int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison)
{
int ret = 0;
*hugetlb = false;
spin_lock_irq(&hugetlb_lock);
if (folio_test_hugetlb(folio)) {
*hugetlb = true;
if (folio_test_hugetlb_freed(folio))
ret = 0;
else if (folio_test_hugetlb_migratable(folio) || unpoison)
ret = folio_try_get(folio);
else
ret = -EBUSY;
}
spin_unlock_irq(&hugetlb_lock);
return ret;
}
int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
bool *migratable_cleared)
{
int ret;
spin_lock_irq(&hugetlb_lock);
ret = __get_huge_page_for_hwpoison(pfn, flags, migratable_cleared);
spin_unlock_irq(&hugetlb_lock);
return ret;
}
void folio_putback_active_hugetlb(struct folio *folio)
{
spin_lock_irq(&hugetlb_lock);
folio_set_hugetlb_migratable(folio);
list_move_tail(&folio->lru, &(folio_hstate(folio))->hugepage_activelist);
spin_unlock_irq(&hugetlb_lock);
folio_put(folio);
}
void move_hugetlb_state(struct folio *old_folio, struct folio *new_folio, int reason)
{
struct hstate *h = folio_hstate(old_folio);
hugetlb_cgroup_migrate(old_folio, new_folio);
set_page_owner_migrate_reason(&new_folio->page, reason);
/*
* transfer temporary state of the new hugetlb folio. This is
* reverse to other transitions because the newpage is going to
* be final while the old one will be freed so it takes over
* the temporary status.
*
* Also note that we have to transfer the per-node surplus state
* here as well otherwise the global surplus count will not match
* the per-node's.
*/
if (folio_test_hugetlb_temporary(new_folio)) {
int old_nid = folio_nid(old_folio);
int new_nid = folio_nid(new_folio);
folio_set_hugetlb_temporary(old_folio);
folio_clear_hugetlb_temporary(new_folio);
/*
* There is no need to transfer the per-node surplus state
* when we do not cross the node.
*/
if (new_nid == old_nid)
return;
spin_lock_irq(&hugetlb_lock);
if (h->surplus_huge_pages_node[old_nid]) {
h->surplus_huge_pages_node[old_nid]--;
h->surplus_huge_pages_node[new_nid]++;
}
spin_unlock_irq(&hugetlb_lock);
}
}
static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
unsigned long start,
unsigned long end)
{
struct hstate *h = hstate_vma(vma);
unsigned long sz = huge_page_size(h);
struct mm_struct *mm = vma->vm_mm;
struct mmu_notifier_range range;
unsigned long address;
spinlock_t *ptl;
pte_t *ptep;
if (!(vma->vm_flags & VM_MAYSHARE))
return;
if (start >= end)
return;
flush_cache_range(vma, start, end);
/*
* No need to call adjust_range_if_pmd_sharing_possible(), because
* we have already done the PUD_SIZE alignment.
*/
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
start, end);
mmu_notifier_invalidate_range_start(&range);
hugetlb_vma_lock_write(vma);
i_mmap_lock_write(vma->vm_file->f_mapping);
for (address = start; address < end; address += PUD_SIZE) {
ptep = hugetlb_walk(vma, address, sz);
if (!ptep)
continue;
ptl = huge_pte_lock(h, mm, ptep);
huge_pmd_unshare(mm, vma, address, ptep);
spin_unlock(ptl);
}
flush_hugetlb_tlb_range(vma, start, end);
i_mmap_unlock_write(vma->vm_file->f_mapping);
hugetlb_vma_unlock_write(vma);
/*
* No need to call mmu_notifier_arch_invalidate_secondary_tlbs(), see
* Documentation/mm/mmu_notifier.rst.
*/
mmu_notifier_invalidate_range_end(&range);
}
/*
* This function will unconditionally remove all the shared pmd pgtable entries
* within the specific vma for a hugetlbfs memory range.
*/
void hugetlb_unshare_all_pmds(struct vm_area_struct *vma)
{
hugetlb_unshare_pmds(vma, ALIGN(vma->vm_start, PUD_SIZE),
ALIGN_DOWN(vma->vm_end, PUD_SIZE));
}
#ifdef CONFIG_CMA
static bool cma_reserve_called __initdata;
static int __init cmdline_parse_hugetlb_cma(char *p)
{
int nid, count = 0;
unsigned long tmp;
char *s = p;
while (*s) {
if (sscanf(s, "%lu%n", &tmp, &count) != 1)
break;
if (s[count] == ':') {
if (tmp >= MAX_NUMNODES)
break;
nid = array_index_nospec(tmp, MAX_NUMNODES);
s += count + 1;
tmp = memparse(s, &s);
hugetlb_cma_size_in_node[nid] = tmp;
hugetlb_cma_size += tmp;
/*
* Skip the separator if have one, otherwise
* break the parsing.
*/
if (*s == ',')
s++;
else
break;
} else {
hugetlb_cma_size = memparse(p, &p);
break;
}
}
return 0;
}
early_param("hugetlb_cma", cmdline_parse_hugetlb_cma);
void __init hugetlb_cma_reserve(int order)
{
unsigned long size, reserved, per_node;
bool node_specific_cma_alloc = false;
int nid;
/*
* HugeTLB CMA reservation is required for gigantic
* huge pages which could not be allocated via the
* page allocator. Just warn if there is any change
* breaking this assumption.
*/
VM_WARN_ON(order <= MAX_PAGE_ORDER);
cma_reserve_called = true;
if (!hugetlb_cma_size)
return;
for (nid = 0; nid < MAX_NUMNODES; nid++) {
if (hugetlb_cma_size_in_node[nid] == 0)
continue;
if (!node_online(nid)) {
pr_warn("hugetlb_cma: invalid node %d specified\n", nid);
hugetlb_cma_size -= hugetlb_cma_size_in_node[nid];
hugetlb_cma_size_in_node[nid] = 0;
continue;
}
if (hugetlb_cma_size_in_node[nid] < (PAGE_SIZE << order)) {
pr_warn("hugetlb_cma: cma area of node %d should be at least %lu MiB\n",
nid, (PAGE_SIZE << order) / SZ_1M);
hugetlb_cma_size -= hugetlb_cma_size_in_node[nid];
hugetlb_cma_size_in_node[nid] = 0;
} else {
node_specific_cma_alloc = true;
}
}
/* Validate the CMA size again in case some invalid nodes specified. */
if (!hugetlb_cma_size)
return;
if (hugetlb_cma_size < (PAGE_SIZE << order)) {
pr_warn("hugetlb_cma: cma area should be at least %lu MiB\n",
(PAGE_SIZE << order) / SZ_1M);
hugetlb_cma_size = 0;
return;
}
if (!node_specific_cma_alloc) {
/*
* If 3 GB area is requested on a machine with 4 numa nodes,
* let's allocate 1 GB on first three nodes and ignore the last one.
*/
per_node = DIV_ROUND_UP(hugetlb_cma_size, nr_online_nodes);
pr_info("hugetlb_cma: reserve %lu MiB, up to %lu MiB per node\n",
hugetlb_cma_size / SZ_1M, per_node / SZ_1M);
}
reserved = 0;
for_each_online_node(nid) {
int res;
char name[CMA_MAX_NAME];
if (node_specific_cma_alloc) {
if (hugetlb_cma_size_in_node[nid] == 0)
continue;
size = hugetlb_cma_size_in_node[nid];
} else {
size = min(per_node, hugetlb_cma_size - reserved);
}
size = round_up(size, PAGE_SIZE << order);
snprintf(name, sizeof(name), "hugetlb%d", nid);
/*
* Note that 'order per bit' is based on smallest size that
* may be returned to CMA allocator in the case of
* huge page demotion.
*/
res = cma_declare_contiguous_nid(0, size, 0,
PAGE_SIZE << order,
HUGETLB_PAGE_ORDER, false, name,
&hugetlb_cma[nid], nid);
if (res) {
pr_warn("hugetlb_cma: reservation failed: err %d, node %d",
res, nid);
continue;
}
reserved += size;
pr_info("hugetlb_cma: reserved %lu MiB on node %d\n",
size / SZ_1M, nid);
if (reserved >= hugetlb_cma_size)
break;
}
if (!reserved)
/*
* hugetlb_cma_size is used to determine if allocations from
* cma are possible. Set to zero if no cma regions are set up.
*/
hugetlb_cma_size = 0;
}
static void __init hugetlb_cma_check(void)
{
if (!hugetlb_cma_size || cma_reserve_called)
return;
pr_warn("hugetlb_cma: the option isn't supported by current arch\n");
}
#endif /* CONFIG_CMA */