linux/mm/hugetlb.c
Andy Whitcroft 84afd99b83 hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits
When a hugetlb mapping with a reservation is split, a new VMA is cloned
from the original.  This new VMA is a direct copy of the original
including the reservation count.  When this pair of VMAs are unmapped we
will incorrect double account the unused reservation and the overall
reservation count will be incorrect, in extreme cases it will wrap.

The problem occurs when we split an existing VMA say to unmap a page in
the middle.  split_vma() will create a new VMA copying all fields from the
original.  As we are storing our reservation count in vm_private_data this
is also copies, endowing the new VMA with a duplicate of the original
VMA's reservation.  Neither of the new VMAs can exhaust these reservations
as they are too small, but when we unmap and close these VMAs we will
incorrect credit the remainder twice and resv_huge_pages will become out
of sync.  This can lead to allocation failures on mappings with
reservations and even to resv_huge_pages wrapping which prevents all
subsequent hugepage allocations.

The simple fix would be to correctly apportion the remaining reservation
count when the split is made.  However the only hook we have vm_ops->open
only has the new VMA we do not know the identity of the preceeding VMA.
Also even if we did have that VMA to hand we do not know how much of the
reservation was consumed each side of the split.

This patch therefore takes a different tack.  We know that the whole of
any private mapping (which has a reservation) has a reservation over its
whole size.  Any present pages represent consumed reservation.  Therefore
if we track the instantiated pages we can calculate the remaining
reservation.

This patch reuses the existing regions code to track the regions for which
we have consumed reservation (ie.  the instantiated pages), as each page
is faulted in we record the consumption of reservation for the new page.
When we need to return unused reservations at unmap time we simply count
the consumed reservation region subtracting that from the whole of the
map.  During a VMA split the newly opened VMA will point to the same
region map, as this map is offset oriented it remains valid for both of
the split VMAs.  This map is referenced counted so that it is removed when
all VMAs which are part of the mmap are gone.

Thanks to Adam Litke and Mel Gorman for their review feedback.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Johannes Weiner <hannes@saeurebad.de>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Jon Tollefson <kniht@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 10:47:16 -07:00

1769 lines
47 KiB
C

/*
* Generic hugetlb support.
* (C) William Irwin, April 2004
*/
#include <linux/gfp.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
#include <linux/nodemask.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <linux/hugetlb.h>
#include "internal.h"
const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
static unsigned long surplus_huge_pages;
static unsigned long nr_overcommit_huge_pages;
unsigned long max_huge_pages;
unsigned long sysctl_overcommit_huge_pages;
static struct list_head hugepage_freelists[MAX_NUMNODES];
static unsigned int nr_huge_pages_node[MAX_NUMNODES];
static unsigned int free_huge_pages_node[MAX_NUMNODES];
static unsigned int surplus_huge_pages_node[MAX_NUMNODES];
static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
unsigned long hugepages_treat_as_movable;
static int hugetlb_next_nid;
/*
* Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
*/
static DEFINE_SPINLOCK(hugetlb_lock);
/*
* Region tracking -- allows tracking of reservations and instantiated pages
* across the pages in a mapping.
*
* The region data structures are protected by a combination of the mmap_sem
* and the hugetlb_instantion_mutex. To access or modify a region the caller
* must either hold the mmap_sem for write, or the mmap_sem for read and
* the hugetlb_instantiation mutex:
*
* down_write(&mm->mmap_sem);
* or
* down_read(&mm->mmap_sem);
* mutex_lock(&hugetlb_instantiation_mutex);
*/
struct file_region {
struct list_head link;
long from;
long to;
};
static long region_add(struct list_head *head, long f, long t)
{
struct file_region *rg, *nrg, *trg;
/* Locate the region we are either in or before. */
list_for_each_entry(rg, head, link)
if (f <= rg->to)
break;
/* Round our left edge to the current segment if it encloses us. */
if (f > rg->from)
f = rg->from;
/* Check for and consume any regions we now overlap with. */
nrg = rg;
list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
if (&rg->link == head)
break;
if (rg->from > t)
break;
/* If this area reaches higher then extend our area to
* include it completely. If this is not the first area
* which we intend to reuse, free it. */
if (rg->to > t)
t = rg->to;
if (rg != nrg) {
list_del(&rg->link);
kfree(rg);
}
}
nrg->from = f;
nrg->to = t;
return 0;
}
static long region_chg(struct list_head *head, long f, long t)
{
struct file_region *rg, *nrg;
long chg = 0;
/* Locate the region we are before or in. */
list_for_each_entry(rg, head, link)
if (f <= rg->to)
break;
/* If we are below the current region then a new region is required.
* Subtle, allocate a new region at the position but make it zero
* size such that we can guarantee to record the reservation. */
if (&rg->link == head || t < rg->from) {
nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
if (!nrg)
return -ENOMEM;
nrg->from = f;
nrg->to = f;
INIT_LIST_HEAD(&nrg->link);
list_add(&nrg->link, rg->link.prev);
return t - f;
}
/* Round our left edge to the current segment if it encloses us. */
if (f > rg->from)
f = rg->from;
chg = t - f;
/* Check for and consume any regions we now overlap with. */
list_for_each_entry(rg, rg->link.prev, link) {
if (&rg->link == head)
break;
if (rg->from > t)
return chg;
/* We overlap with this area, if it extends futher than
* us then we must extend ourselves. Account for its
* existing reservation. */
if (rg->to > t) {
chg += rg->to - t;
t = rg->to;
}
chg -= rg->to - rg->from;
}
return chg;
}
static long region_truncate(struct list_head *head, long end)
{
struct file_region *rg, *trg;
long chg = 0;
/* Locate the region we are either in or before. */
list_for_each_entry(rg, head, link)
if (end <= rg->to)
break;
if (&rg->link == head)
return 0;
/* If we are in the middle of a region then adjust it. */
if (end > rg->from) {
chg = rg->to - end;
rg->to = end;
rg = list_entry(rg->link.next, typeof(*rg), link);
}
/* Drop any remaining regions. */
list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
if (&rg->link == head)
break;
chg += rg->to - rg->from;
list_del(&rg->link);
kfree(rg);
}
return chg;
}
static long region_count(struct list_head *head, long f, long t)
{
struct file_region *rg;
long chg = 0;
/* Locate each segment we overlap with, and count that overlap. */
list_for_each_entry(rg, head, link) {
int seg_from;
int 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;
}
return chg;
}
/*
* Convert the address within this vma to the page offset within
* the mapping, in base page units.
*/
static pgoff_t vma_page_offset(struct vm_area_struct *vma,
unsigned long address)
{
return ((address - vma->vm_start) >> PAGE_SHIFT) +
(vma->vm_pgoff >> PAGE_SHIFT);
}
/*
* Convert the address within this vma to the page offset within
* the mapping, in pagecache page units; huge pages here.
*/
static pgoff_t vma_pagecache_offset(struct vm_area_struct *vma,
unsigned long address)
{
return ((address - vma->vm_start) >> HPAGE_SHIFT) +
(vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
}
/*
* 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 reset_vma_resv_huge_pages() 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;
}
struct resv_map {
struct kref refs;
struct list_head regions;
};
struct resv_map *resv_map_alloc(void)
{
struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
if (!resv_map)
return NULL;
kref_init(&resv_map->refs);
INIT_LIST_HEAD(&resv_map->regions);
return resv_map;
}
void resv_map_release(struct kref *ref)
{
struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
/* Clear out any active regions before we release the map. */
region_truncate(&resv_map->regions, 0);
kfree(resv_map);
}
static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
if (!(vma->vm_flags & VM_SHARED))
return (struct resv_map *)(get_vma_private_data(vma) &
~HPAGE_RESV_MASK);
return 0;
}
static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
VM_BUG_ON(vma->vm_flags & VM_SHARED);
set_vma_private_data(vma, (get_vma_private_data(vma) &
HPAGE_RESV_MASK) | (unsigned long)map);
}
static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
VM_BUG_ON(vma->vm_flags & VM_SHARED);
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(!is_vm_hugetlb_page(vma));
return (get_vma_private_data(vma) & flag) != 0;
}
/* Decrement the reserved pages in the hugepage pool by one */
static void decrement_hugepage_resv_vma(struct vm_area_struct *vma)
{
if (vma->vm_flags & VM_NORESERVE)
return;
if (vma->vm_flags & VM_SHARED) {
/* Shared mappings always use reserves */
resv_huge_pages--;
} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
/*
* Only the process that called mmap() has reserves for
* private mappings.
*/
resv_huge_pages--;
}
}
/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
if (!(vma->vm_flags & VM_SHARED))
vma->vm_private_data = (void *)0;
}
/* Returns true if the VMA has associated reserve pages */
static int vma_has_private_reserves(struct vm_area_struct *vma)
{
if (vma->vm_flags & VM_SHARED)
return 0;
if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER))
return 0;
return 1;
}
static void clear_huge_page(struct page *page, unsigned long addr)
{
int i;
might_sleep();
for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
cond_resched();
clear_user_highpage(page + i, addr + i * PAGE_SIZE);
}
}
static void copy_huge_page(struct page *dst, struct page *src,
unsigned long addr, struct vm_area_struct *vma)
{
int i;
might_sleep();
for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
cond_resched();
copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
}
}
static void enqueue_huge_page(struct page *page)
{
int nid = page_to_nid(page);
list_add(&page->lru, &hugepage_freelists[nid]);
free_huge_pages++;
free_huge_pages_node[nid]++;
}
static struct page *dequeue_huge_page(void)
{
int nid;
struct page *page = NULL;
for (nid = 0; nid < MAX_NUMNODES; ++nid) {
if (!list_empty(&hugepage_freelists[nid])) {
page = list_entry(hugepage_freelists[nid].next,
struct page, lru);
list_del(&page->lru);
free_huge_pages--;
free_huge_pages_node[nid]--;
break;
}
}
return page;
}
static struct page *dequeue_huge_page_vma(struct vm_area_struct *vma,
unsigned long address, int avoid_reserve)
{
int nid;
struct page *page = NULL;
struct mempolicy *mpol;
nodemask_t *nodemask;
struct zonelist *zonelist = huge_zonelist(vma, address,
htlb_alloc_mask, &mpol, &nodemask);
struct zone *zone;
struct zoneref *z;
/*
* 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_private_reserves(vma) &&
free_huge_pages - resv_huge_pages == 0)
return NULL;
/* If reserves cannot be used, ensure enough pages are in the pool */
if (avoid_reserve && free_huge_pages - resv_huge_pages == 0)
return NULL;
for_each_zone_zonelist_nodemask(zone, z, zonelist,
MAX_NR_ZONES - 1, nodemask) {
nid = zone_to_nid(zone);
if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
!list_empty(&hugepage_freelists[nid])) {
page = list_entry(hugepage_freelists[nid].next,
struct page, lru);
list_del(&page->lru);
free_huge_pages--;
free_huge_pages_node[nid]--;
if (!avoid_reserve)
decrement_hugepage_resv_vma(vma);
break;
}
}
mpol_cond_put(mpol);
return page;
}
static void update_and_free_page(struct page *page)
{
int i;
nr_huge_pages--;
nr_huge_pages_node[page_to_nid(page)]--;
for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
1 << PG_private | 1<< PG_writeback);
}
set_compound_page_dtor(page, NULL);
set_page_refcounted(page);
arch_release_hugepage(page);
__free_pages(page, HUGETLB_PAGE_ORDER);
}
static void free_huge_page(struct page *page)
{
int nid = page_to_nid(page);
struct address_space *mapping;
mapping = (struct address_space *) page_private(page);
set_page_private(page, 0);
BUG_ON(page_count(page));
INIT_LIST_HEAD(&page->lru);
spin_lock(&hugetlb_lock);
if (surplus_huge_pages_node[nid]) {
update_and_free_page(page);
surplus_huge_pages--;
surplus_huge_pages_node[nid]--;
} else {
enqueue_huge_page(page);
}
spin_unlock(&hugetlb_lock);
if (mapping)
hugetlb_put_quota(mapping, 1);
}
/*
* 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(int delta)
{
static int prev_nid;
int nid = prev_nid;
int ret = 0;
VM_BUG_ON(delta != -1 && delta != 1);
do {
nid = next_node(nid, node_online_map);
if (nid == MAX_NUMNODES)
nid = first_node(node_online_map);
/* To shrink on this node, there must be a surplus page */
if (delta < 0 && !surplus_huge_pages_node[nid])
continue;
/* Surplus cannot exceed the total number of pages */
if (delta > 0 && surplus_huge_pages_node[nid] >=
nr_huge_pages_node[nid])
continue;
surplus_huge_pages += delta;
surplus_huge_pages_node[nid] += delta;
ret = 1;
break;
} while (nid != prev_nid);
prev_nid = nid;
return ret;
}
static struct page *alloc_fresh_huge_page_node(int nid)
{
struct page *page;
page = alloc_pages_node(nid,
htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
__GFP_REPEAT|__GFP_NOWARN,
HUGETLB_PAGE_ORDER);
if (page) {
if (arch_prepare_hugepage(page)) {
__free_pages(page, HUGETLB_PAGE_ORDER);
return NULL;
}
set_compound_page_dtor(page, free_huge_page);
spin_lock(&hugetlb_lock);
nr_huge_pages++;
nr_huge_pages_node[nid]++;
spin_unlock(&hugetlb_lock);
put_page(page); /* free it into the hugepage allocator */
}
return page;
}
static int alloc_fresh_huge_page(void)
{
struct page *page;
int start_nid;
int next_nid;
int ret = 0;
start_nid = hugetlb_next_nid;
do {
page = alloc_fresh_huge_page_node(hugetlb_next_nid);
if (page)
ret = 1;
/*
* Use a helper variable to find the next node and then
* copy it back to hugetlb_next_nid afterwards:
* otherwise there's a window in which a racer might
* pass invalid nid MAX_NUMNODES to alloc_pages_node.
* But we don't need to use a spin_lock here: it really
* doesn't matter if occasionally a racer chooses the
* same nid as we do. Move nid forward in the mask even
* if we just successfully allocated a hugepage so that
* the next caller gets hugepages on the next node.
*/
next_nid = next_node(hugetlb_next_nid, node_online_map);
if (next_nid == MAX_NUMNODES)
next_nid = first_node(node_online_map);
hugetlb_next_nid = next_nid;
} while (!page && hugetlb_next_nid != start_nid);
if (ret)
count_vm_event(HTLB_BUDDY_PGALLOC);
else
count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
return ret;
}
static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
unsigned long address)
{
struct page *page;
unsigned int nid;
/*
* Assume we will successfully allocate the surplus page to
* prevent racing processes from causing the surplus to exceed
* overcommit
*
* This however introduces a different race, where a process B
* tries to grow the static hugepage pool while alloc_pages() is
* called by process A. B will only examine the per-node
* counters in determining if surplus huge pages can be
* converted to normal huge pages in adjust_pool_surplus(). A
* won't be able to increment the per-node counter, until the
* lock is dropped by B, but B doesn't drop hugetlb_lock until
* no more huge pages can be converted from surplus to normal
* state (and doesn't try to convert again). Thus, we have a
* case where a surplus huge page exists, the pool is grown, and
* the surplus huge page still exists after, even though it
* should just have been converted to a normal huge page. This
* does not leak memory, though, as the hugepage will be freed
* once it is out of use. It also does not allow the counters to
* go out of whack in adjust_pool_surplus() as we don't modify
* the node values until we've gotten the hugepage and only the
* per-node value is checked there.
*/
spin_lock(&hugetlb_lock);
if (surplus_huge_pages >= nr_overcommit_huge_pages) {
spin_unlock(&hugetlb_lock);
return NULL;
} else {
nr_huge_pages++;
surplus_huge_pages++;
}
spin_unlock(&hugetlb_lock);
page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
__GFP_REPEAT|__GFP_NOWARN,
HUGETLB_PAGE_ORDER);
spin_lock(&hugetlb_lock);
if (page) {
/*
* This page is now managed by the hugetlb allocator and has
* no users -- drop the buddy allocator's reference.
*/
put_page_testzero(page);
VM_BUG_ON(page_count(page));
nid = page_to_nid(page);
set_compound_page_dtor(page, free_huge_page);
/*
* We incremented the global counters already
*/
nr_huge_pages_node[nid]++;
surplus_huge_pages_node[nid]++;
__count_vm_event(HTLB_BUDDY_PGALLOC);
} else {
nr_huge_pages--;
surplus_huge_pages--;
__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
}
spin_unlock(&hugetlb_lock);
return page;
}
/*
* Increase the hugetlb pool such that it can accomodate a reservation
* of size 'delta'.
*/
static int gather_surplus_pages(int delta)
{
struct list_head surplus_list;
struct page *page, *tmp;
int ret, i;
int needed, allocated;
needed = (resv_huge_pages + delta) - free_huge_pages;
if (needed <= 0) {
resv_huge_pages += delta;
return 0;
}
allocated = 0;
INIT_LIST_HEAD(&surplus_list);
ret = -ENOMEM;
retry:
spin_unlock(&hugetlb_lock);
for (i = 0; i < needed; i++) {
page = alloc_buddy_huge_page(NULL, 0);
if (!page) {
/*
* We were not able to allocate enough pages to
* satisfy the entire reservation so we free what
* we've allocated so far.
*/
spin_lock(&hugetlb_lock);
needed = 0;
goto free;
}
list_add(&page->lru, &surplus_list);
}
allocated += needed;
/*
* After retaking hugetlb_lock, we need to recalculate 'needed'
* because either resv_huge_pages or free_huge_pages may have changed.
*/
spin_lock(&hugetlb_lock);
needed = (resv_huge_pages + delta) - (free_huge_pages + allocated);
if (needed > 0)
goto retry;
/*
* The surplus_list now contains _at_least_ the number of extra pages
* needed to accomodate 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;
resv_huge_pages += delta;
ret = 0;
free:
/* Free the needed pages to the hugetlb pool */
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
if ((--needed) < 0)
break;
list_del(&page->lru);
enqueue_huge_page(page);
}
/* Free unnecessary surplus pages to the buddy allocator */
if (!list_empty(&surplus_list)) {
spin_unlock(&hugetlb_lock);
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
list_del(&page->lru);
/*
* The page has a reference count of zero already, so
* call free_huge_page directly instead of using
* put_page. This must be done with hugetlb_lock
* unlocked which is safe because free_huge_page takes
* hugetlb_lock before deciding how to free the page.
*/
free_huge_page(page);
}
spin_lock(&hugetlb_lock);
}
return ret;
}
/*
* When releasing a hugetlb pool reservation, any surplus pages that were
* allocated to satisfy the reservation must be explicitly freed if they were
* never used.
*/
static void return_unused_surplus_pages(unsigned long unused_resv_pages)
{
static int nid = -1;
struct page *page;
unsigned long nr_pages;
/*
* We want to release as many surplus pages as possible, spread
* evenly across all nodes. Iterate across all nodes until we
* can no longer free unreserved surplus pages. This occurs when
* the nodes with surplus pages have no free pages.
*/
unsigned long remaining_iterations = num_online_nodes();
/* Uncommit the reservation */
resv_huge_pages -= unused_resv_pages;
nr_pages = min(unused_resv_pages, surplus_huge_pages);
while (remaining_iterations-- && nr_pages) {
nid = next_node(nid, node_online_map);
if (nid == MAX_NUMNODES)
nid = first_node(node_online_map);
if (!surplus_huge_pages_node[nid])
continue;
if (!list_empty(&hugepage_freelists[nid])) {
page = list_entry(hugepage_freelists[nid].next,
struct page, lru);
list_del(&page->lru);
update_and_free_page(page);
free_huge_pages--;
free_huge_pages_node[nid]--;
surplus_huge_pages--;
surplus_huge_pages_node[nid]--;
nr_pages--;
remaining_iterations = num_online_nodes();
}
}
}
/*
* Determine if the huge page at addr within the vma has an associated
* reservation. Where it does not we will need to logically increase
* reservation and actually increase quota before an allocation can occur.
* Where any new reservation would be required the reservation change is
* prepared, but not committed. Once the page has been quota'd allocated
* an instantiated the change should be committed via vma_commit_reservation.
* No action is required on failure.
*/
static int vma_needs_reservation(struct vm_area_struct *vma, unsigned long addr)
{
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
if (vma->vm_flags & VM_SHARED) {
pgoff_t idx = vma_pagecache_offset(vma, addr);
return region_chg(&inode->i_mapping->private_list,
idx, idx + 1);
} else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
return 1;
} else {
int err;
pgoff_t idx = vma_pagecache_offset(vma, addr);
struct resv_map *reservations = vma_resv_map(vma);
err = region_chg(&reservations->regions, idx, idx + 1);
if (err < 0)
return err;
return 0;
}
}
static void vma_commit_reservation(struct vm_area_struct *vma,
unsigned long addr)
{
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
if (vma->vm_flags & VM_SHARED) {
pgoff_t idx = vma_pagecache_offset(vma, addr);
region_add(&inode->i_mapping->private_list, idx, idx + 1);
} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
pgoff_t idx = vma_pagecache_offset(vma, addr);
struct resv_map *reservations = vma_resv_map(vma);
/* Mark this page used in the map. */
region_add(&reservations->regions, idx, idx + 1);
}
}
static struct page *alloc_huge_page(struct vm_area_struct *vma,
unsigned long addr, int avoid_reserve)
{
struct page *page;
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
unsigned int chg;
/*
* Processes that did not create the mapping will have no reserves and
* will not have accounted against quota. Check that the quota can be
* made before satisfying the allocation
* MAP_NORESERVE mappings may also need pages and quota allocated
* if no reserve mapping overlaps.
*/
chg = vma_needs_reservation(vma, addr);
if (chg < 0)
return ERR_PTR(chg);
if (chg)
if (hugetlb_get_quota(inode->i_mapping, chg))
return ERR_PTR(-ENOSPC);
spin_lock(&hugetlb_lock);
page = dequeue_huge_page_vma(vma, addr, avoid_reserve);
spin_unlock(&hugetlb_lock);
if (!page) {
page = alloc_buddy_huge_page(vma, addr);
if (!page) {
hugetlb_put_quota(inode->i_mapping, chg);
return ERR_PTR(-VM_FAULT_OOM);
}
}
set_page_refcounted(page);
set_page_private(page, (unsigned long) mapping);
vma_commit_reservation(vma, addr);
return page;
}
static int __init hugetlb_init(void)
{
unsigned long i;
if (HPAGE_SHIFT == 0)
return 0;
for (i = 0; i < MAX_NUMNODES; ++i)
INIT_LIST_HEAD(&hugepage_freelists[i]);
hugetlb_next_nid = first_node(node_online_map);
for (i = 0; i < max_huge_pages; ++i) {
if (!alloc_fresh_huge_page())
break;
}
max_huge_pages = free_huge_pages = nr_huge_pages = i;
printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
return 0;
}
module_init(hugetlb_init);
static int __init hugetlb_setup(char *s)
{
if (sscanf(s, "%lu", &max_huge_pages) <= 0)
max_huge_pages = 0;
return 1;
}
__setup("hugepages=", hugetlb_setup);
static unsigned int cpuset_mems_nr(unsigned int *array)
{
int node;
unsigned int nr = 0;
for_each_node_mask(node, cpuset_current_mems_allowed)
nr += array[node];
return nr;
}
#ifdef CONFIG_SYSCTL
#ifdef CONFIG_HIGHMEM
static void try_to_free_low(unsigned long count)
{
int i;
for (i = 0; i < MAX_NUMNODES; ++i) {
struct page *page, *next;
list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
if (count >= nr_huge_pages)
return;
if (PageHighMem(page))
continue;
list_del(&page->lru);
update_and_free_page(page);
free_huge_pages--;
free_huge_pages_node[page_to_nid(page)]--;
}
}
}
#else
static inline void try_to_free_low(unsigned long count)
{
}
#endif
#define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
static unsigned long set_max_huge_pages(unsigned long count)
{
unsigned long min_count, ret;
/*
* 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_buddy_huge_page() 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.
*/
spin_lock(&hugetlb_lock);
while (surplus_huge_pages && count > persistent_huge_pages) {
if (!adjust_pool_surplus(-1))
break;
}
while (count > persistent_huge_pages) {
/*
* If this allocation races such that we no longer need the
* page, free_huge_page will handle it by freeing the page
* and reducing the surplus.
*/
spin_unlock(&hugetlb_lock);
ret = alloc_fresh_huge_page();
spin_lock(&hugetlb_lock);
if (!ret)
goto out;
}
/*
* 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_buddy_huge_page() 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 = resv_huge_pages + nr_huge_pages - free_huge_pages;
min_count = max(count, min_count);
try_to_free_low(min_count);
while (min_count < persistent_huge_pages) {
struct page *page = dequeue_huge_page();
if (!page)
break;
update_and_free_page(page);
}
while (count < persistent_huge_pages) {
if (!adjust_pool_surplus(1))
break;
}
out:
ret = persistent_huge_pages;
spin_unlock(&hugetlb_lock);
return ret;
}
int hugetlb_sysctl_handler(struct ctl_table *table, int write,
struct file *file, void __user *buffer,
size_t *length, loff_t *ppos)
{
proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
max_huge_pages = set_max_huge_pages(max_huge_pages);
return 0;
}
int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
struct file *file, void __user *buffer,
size_t *length, loff_t *ppos)
{
proc_dointvec(table, write, file, buffer, length, ppos);
if (hugepages_treat_as_movable)
htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
else
htlb_alloc_mask = GFP_HIGHUSER;
return 0;
}
int hugetlb_overcommit_handler(struct ctl_table *table, int write,
struct file *file, void __user *buffer,
size_t *length, loff_t *ppos)
{
proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
spin_lock(&hugetlb_lock);
nr_overcommit_huge_pages = sysctl_overcommit_huge_pages;
spin_unlock(&hugetlb_lock);
return 0;
}
#endif /* CONFIG_SYSCTL */
int hugetlb_report_meminfo(char *buf)
{
return sprintf(buf,
"HugePages_Total: %5lu\n"
"HugePages_Free: %5lu\n"
"HugePages_Rsvd: %5lu\n"
"HugePages_Surp: %5lu\n"
"Hugepagesize: %5lu kB\n",
nr_huge_pages,
free_huge_pages,
resv_huge_pages,
surplus_huge_pages,
HPAGE_SIZE/1024);
}
int hugetlb_report_node_meminfo(int nid, char *buf)
{
return sprintf(buf,
"Node %d HugePages_Total: %5u\n"
"Node %d HugePages_Free: %5u\n"
"Node %d HugePages_Surp: %5u\n",
nid, nr_huge_pages_node[nid],
nid, free_huge_pages_node[nid],
nid, surplus_huge_pages_node[nid]);
}
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
}
static int hugetlb_acct_memory(long delta)
{
int ret = -ENOMEM;
spin_lock(&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.
*/
if (delta > 0) {
if (gather_surplus_pages(delta) < 0)
goto out;
if (delta > cpuset_mems_nr(free_huge_pages_node)) {
return_unused_surplus_pages(delta);
goto out;
}
}
ret = 0;
if (delta < 0)
return_unused_surplus_pages((unsigned long) -delta);
out:
spin_unlock(&hugetlb_lock);
return ret;
}
static void hugetlb_vm_op_open(struct vm_area_struct *vma)
{
struct resv_map *reservations = vma_resv_map(vma);
/*
* 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 dissappear until
* after this open call completes. It is therefore safe to take a
* new reference here without additional locking.
*/
if (reservations)
kref_get(&reservations->refs);
}
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
struct resv_map *reservations = vma_resv_map(vma);
unsigned long reserve;
unsigned long start;
unsigned long end;
if (reservations) {
start = vma_pagecache_offset(vma, vma->vm_start);
end = vma_pagecache_offset(vma, vma->vm_end);
reserve = (end - start) -
region_count(&reservations->regions, start, end);
kref_put(&reservations->refs, resv_map_release);
if (reserve)
hugetlb_acct_memory(-reserve);
}
}
/*
* We cannot handle pagefaults against hugetlb pages at all. They cause
* handle_mm_fault() to try to instantiate regular-sized pages in the
* hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
* this far.
*/
static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
BUG();
return 0;
}
struct vm_operations_struct hugetlb_vm_ops = {
.fault = hugetlb_vm_op_fault,
.open = hugetlb_vm_op_open,
.close = hugetlb_vm_op_close,
};
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
int writable)
{
pte_t entry;
if (writable) {
entry =
pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
} else {
entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
}
entry = pte_mkyoung(entry);
entry = pte_mkhuge(entry);
return entry;
}
static void set_huge_ptep_writable(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep)
{
pte_t entry;
entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
update_mmu_cache(vma, address, entry);
}
}
int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
struct vm_area_struct *vma)
{
pte_t *src_pte, *dst_pte, entry;
struct page *ptepage;
unsigned long addr;
int cow;
cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
src_pte = huge_pte_offset(src, addr);
if (!src_pte)
continue;
dst_pte = huge_pte_alloc(dst, addr);
if (!dst_pte)
goto nomem;
/* If the pagetables are shared don't copy or take references */
if (dst_pte == src_pte)
continue;
spin_lock(&dst->page_table_lock);
spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
if (!huge_pte_none(huge_ptep_get(src_pte))) {
if (cow)
huge_ptep_set_wrprotect(src, addr, src_pte);
entry = huge_ptep_get(src_pte);
ptepage = pte_page(entry);
get_page(ptepage);
set_huge_pte_at(dst, addr, dst_pte, entry);
}
spin_unlock(&src->page_table_lock);
spin_unlock(&dst->page_table_lock);
}
return 0;
nomem:
return -ENOMEM;
}
void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end, struct page *ref_page)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long address;
pte_t *ptep;
pte_t pte;
struct page *page;
struct page *tmp;
/*
* A page gathering list, protected by per file i_mmap_lock. The
* lock is used to avoid list corruption from multiple unmapping
* of the same page since we are using page->lru.
*/
LIST_HEAD(page_list);
WARN_ON(!is_vm_hugetlb_page(vma));
BUG_ON(start & ~HPAGE_MASK);
BUG_ON(end & ~HPAGE_MASK);
spin_lock(&mm->page_table_lock);
for (address = start; address < end; address += HPAGE_SIZE) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
if (huge_pmd_unshare(mm, &address, ptep))
continue;
/*
* 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) {
pte = huge_ptep_get(ptep);
if (huge_pte_none(pte))
continue;
page = pte_page(pte);
if (page != ref_page)
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);
if (huge_pte_none(pte))
continue;
page = pte_page(pte);
if (pte_dirty(pte))
set_page_dirty(page);
list_add(&page->lru, &page_list);
}
spin_unlock(&mm->page_table_lock);
flush_tlb_range(vma, start, end);
list_for_each_entry_safe(page, tmp, &page_list, lru) {
list_del(&page->lru);
put_page(page);
}
}
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end, struct page *ref_page)
{
/*
* It is undesirable to test vma->vm_file as it should be non-null
* for valid hugetlb area. However, vm_file will be NULL in the error
* cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
* do_mmap_pgoff() nullifies vma->vm_file before calling this function
* to clean up. Since no pte has actually been setup, it is safe to
* do nothing in this case.
*/
if (vma->vm_file) {
spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
__unmap_hugepage_range(vma, start, end, ref_page);
spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
}
}
/*
* This is called when the original mapper is failing to COW a MAP_PRIVATE
* mappping 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.
*/
int unmap_ref_private(struct mm_struct *mm,
struct vm_area_struct *vma,
struct page *page,
unsigned long address)
{
struct vm_area_struct *iter_vma;
struct address_space *mapping;
struct prio_tree_iter iter;
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(hstate_vma(vma));
pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
+ (vma->vm_pgoff >> PAGE_SHIFT);
mapping = (struct address_space *)page_private(page);
vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
/* Do not unmap the current VMA */
if (iter_vma == vma)
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 + HPAGE_SIZE,
page);
}
return 1;
}
static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, pte_t *ptep, pte_t pte,
struct page *pagecache_page)
{
struct page *old_page, *new_page;
int avoidcopy;
int outside_reserve = 0;
old_page = pte_page(pte);
retry_avoidcopy:
/* If no-one else is actually using this page, avoid the copy
* and just make the page writable */
avoidcopy = (page_count(old_page) == 1);
if (avoidcopy) {
set_huge_ptep_writable(vma, address, ptep);
return 0;
}
/*
* 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 (!(vma->vm_flags & VM_SHARED) &&
is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
old_page != pagecache_page)
outside_reserve = 1;
page_cache_get(old_page);
new_page = alloc_huge_page(vma, address, outside_reserve);
if (IS_ERR(new_page)) {
page_cache_release(old_page);
/*
* 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) {
BUG_ON(huge_pte_none(pte));
if (unmap_ref_private(mm, vma, old_page, address)) {
BUG_ON(page_count(old_page) != 1);
BUG_ON(huge_pte_none(pte));
goto retry_avoidcopy;
}
WARN_ON_ONCE(1);
}
return -PTR_ERR(new_page);
}
spin_unlock(&mm->page_table_lock);
copy_huge_page(new_page, old_page, address, vma);
__SetPageUptodate(new_page);
spin_lock(&mm->page_table_lock);
ptep = huge_pte_offset(mm, address & HPAGE_MASK);
if (likely(pte_same(huge_ptep_get(ptep), pte))) {
/* Break COW */
huge_ptep_clear_flush(vma, address, ptep);
set_huge_pte_at(mm, address, ptep,
make_huge_pte(vma, new_page, 1));
/* Make the old page be freed below */
new_page = old_page;
}
page_cache_release(new_page);
page_cache_release(old_page);
return 0;
}
/* Return the pagecache page at a given address within a VMA */
static struct page *hugetlbfs_pagecache_page(struct vm_area_struct *vma,
unsigned long address)
{
struct address_space *mapping;
pgoff_t idx;
mapping = vma->vm_file->f_mapping;
idx = vma_pagecache_offset(vma, address);
return find_lock_page(mapping, idx);
}
static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, pte_t *ptep, int write_access)
{
int ret = VM_FAULT_SIGBUS;
pgoff_t idx;
unsigned long size;
struct page *page;
struct address_space *mapping;
pte_t new_pte;
/*
* 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. Warn that such a situation has occured as it may not be obvious
*/
if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
printk(KERN_WARNING
"PID %d killed due to inadequate hugepage pool\n",
current->pid);
return ret;
}
mapping = vma->vm_file->f_mapping;
idx = vma_pagecache_offset(vma, address);
/*
* Use page lock to guard against racing truncation
* before we get page_table_lock.
*/
retry:
page = find_lock_page(mapping, idx);
if (!page) {
size = i_size_read(mapping->host) >> HPAGE_SHIFT;
if (idx >= size)
goto out;
page = alloc_huge_page(vma, address, 0);
if (IS_ERR(page)) {
ret = -PTR_ERR(page);
goto out;
}
clear_huge_page(page, address);
__SetPageUptodate(page);
if (vma->vm_flags & VM_SHARED) {
int err;
struct inode *inode = mapping->host;
err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
if (err) {
put_page(page);
if (err == -EEXIST)
goto retry;
goto out;
}
spin_lock(&inode->i_lock);
inode->i_blocks += BLOCKS_PER_HUGEPAGE;
spin_unlock(&inode->i_lock);
} else
lock_page(page);
}
spin_lock(&mm->page_table_lock);
size = i_size_read(mapping->host) >> HPAGE_SHIFT;
if (idx >= size)
goto backout;
ret = 0;
if (!huge_pte_none(huge_ptep_get(ptep)))
goto backout;
new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
set_huge_pte_at(mm, address, ptep, new_pte);
if (write_access && !(vma->vm_flags & VM_SHARED)) {
/* Optimization, do the COW without a second fault */
ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
}
spin_unlock(&mm->page_table_lock);
unlock_page(page);
out:
return ret;
backout:
spin_unlock(&mm->page_table_lock);
unlock_page(page);
put_page(page);
goto out;
}
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, int write_access)
{
pte_t *ptep;
pte_t entry;
int ret;
static DEFINE_MUTEX(hugetlb_instantiation_mutex);
ptep = huge_pte_alloc(mm, address);
if (!ptep)
return VM_FAULT_OOM;
/*
* 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.
*/
mutex_lock(&hugetlb_instantiation_mutex);
entry = huge_ptep_get(ptep);
if (huge_pte_none(entry)) {
ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
mutex_unlock(&hugetlb_instantiation_mutex);
return ret;
}
ret = 0;
spin_lock(&mm->page_table_lock);
/* Check for a racing update before calling hugetlb_cow */
if (likely(pte_same(entry, huge_ptep_get(ptep))))
if (write_access && !pte_write(entry)) {
struct page *page;
page = hugetlbfs_pagecache_page(vma, address);
ret = hugetlb_cow(mm, vma, address, ptep, entry, page);
if (page) {
unlock_page(page);
put_page(page);
}
}
spin_unlock(&mm->page_table_lock);
mutex_unlock(&hugetlb_instantiation_mutex);
return ret;
}
int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page **pages, struct vm_area_struct **vmas,
unsigned long *position, int *length, int i,
int write)
{
unsigned long pfn_offset;
unsigned long vaddr = *position;
int remainder = *length;
spin_lock(&mm->page_table_lock);
while (vaddr < vma->vm_end && remainder) {
pte_t *pte;
struct page *page;
/*
* Some archs (sparc64, sh*) have multiple pte_ts to
* each hugepage. We have to make * sure we get the
* first, for the page indexing below to work.
*/
pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
if (!pte || huge_pte_none(huge_ptep_get(pte)) ||
(write && !pte_write(huge_ptep_get(pte)))) {
int ret;
spin_unlock(&mm->page_table_lock);
ret = hugetlb_fault(mm, vma, vaddr, write);
spin_lock(&mm->page_table_lock);
if (!(ret & VM_FAULT_ERROR))
continue;
remainder = 0;
if (!i)
i = -EFAULT;
break;
}
pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
page = pte_page(huge_ptep_get(pte));
same_page:
if (pages) {
get_page(page);
pages[i] = page + pfn_offset;
}
if (vmas)
vmas[i] = vma;
vaddr += PAGE_SIZE;
++pfn_offset;
--remainder;
++i;
if (vaddr < vma->vm_end && remainder &&
pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
/*
* We use pfn_offset to avoid touching the pageframes
* of this compound page.
*/
goto same_page;
}
}
spin_unlock(&mm->page_table_lock);
*length = remainder;
*position = vaddr;
return i;
}
void hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end, pgprot_t newprot)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long start = address;
pte_t *ptep;
pte_t pte;
BUG_ON(address >= end);
flush_cache_range(vma, address, end);
spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
spin_lock(&mm->page_table_lock);
for (; address < end; address += HPAGE_SIZE) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
if (huge_pmd_unshare(mm, &address, ptep))
continue;
if (!huge_pte_none(huge_ptep_get(ptep))) {
pte = huge_ptep_get_and_clear(mm, address, ptep);
pte = pte_mkhuge(pte_modify(pte, newprot));
set_huge_pte_at(mm, address, ptep, pte);
}
}
spin_unlock(&mm->page_table_lock);
spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
flush_tlb_range(vma, start, end);
}
int hugetlb_reserve_pages(struct inode *inode,
long from, long to,
struct vm_area_struct *vma)
{
long ret, chg;
if (vma && vma->vm_flags & VM_NORESERVE)
return 0;
/*
* 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_SHARED)
chg = region_chg(&inode->i_mapping->private_list, from, to);
else {
struct resv_map *resv_map = resv_map_alloc();
if (!resv_map)
return -ENOMEM;
chg = to - from;
set_vma_resv_map(vma, resv_map);
set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
}
if (chg < 0)
return chg;
if (hugetlb_get_quota(inode->i_mapping, chg))
return -ENOSPC;
ret = hugetlb_acct_memory(chg);
if (ret < 0) {
hugetlb_put_quota(inode->i_mapping, chg);
return ret;
}
if (!vma || vma->vm_flags & VM_SHARED)
region_add(&inode->i_mapping->private_list, from, to);
return 0;
}
void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
{
long chg = region_truncate(&inode->i_mapping->private_list, offset);
spin_lock(&inode->i_lock);
inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
spin_unlock(&inode->i_lock);
hugetlb_put_quota(inode->i_mapping, (chg - freed));
hugetlb_acct_memory(-(chg - freed));
}