linux/mm/memcontrol.c
KAMEZAWA Hiroyuki 3564c7c451 memory cgroup enhancements: remember "a page is on active list of cgroup or not"
Remember page_cgroup is on active_list or not in page_cgroup->flags.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-07 08:42:20 -08:00

839 lines
20 KiB
C

/* memcontrol.c - Memory Controller
*
* Copyright IBM Corporation, 2007
* Author Balbir Singh <balbir@linux.vnet.ibm.com>
*
* Copyright 2007 OpenVZ SWsoft Inc
* Author: Pavel Emelianov <xemul@openvz.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/res_counter.h>
#include <linux/memcontrol.h>
#include <linux/cgroup.h>
#include <linux/mm.h>
#include <linux/page-flags.h>
#include <linux/backing-dev.h>
#include <linux/bit_spinlock.h>
#include <linux/rcupdate.h>
#include <linux/swap.h>
#include <linux/spinlock.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
struct cgroup_subsys mem_cgroup_subsys;
static const int MEM_CGROUP_RECLAIM_RETRIES = 5;
/*
* The memory controller data structure. The memory controller controls both
* page cache and RSS per cgroup. We would eventually like to provide
* statistics based on the statistics developed by Rik Van Riel for clock-pro,
* to help the administrator determine what knobs to tune.
*
* TODO: Add a water mark for the memory controller. Reclaim will begin when
* we hit the water mark. May be even add a low water mark, such that
* no reclaim occurs from a cgroup at it's low water mark, this is
* a feature that will be implemented much later in the future.
*/
struct mem_cgroup {
struct cgroup_subsys_state css;
/*
* the counter to account for memory usage
*/
struct res_counter res;
/*
* Per cgroup active and inactive list, similar to the
* per zone LRU lists.
* TODO: Consider making these lists per zone
*/
struct list_head active_list;
struct list_head inactive_list;
/*
* spin_lock to protect the per cgroup LRU
*/
spinlock_t lru_lock;
unsigned long control_type; /* control RSS or RSS+Pagecache */
};
/*
* We use the lower bit of the page->page_cgroup pointer as a bit spin
* lock. We need to ensure that page->page_cgroup is atleast two
* byte aligned (based on comments from Nick Piggin)
*/
#define PAGE_CGROUP_LOCK_BIT 0x0
#define PAGE_CGROUP_LOCK (1 << PAGE_CGROUP_LOCK_BIT)
/*
* A page_cgroup page is associated with every page descriptor. The
* page_cgroup helps us identify information about the cgroup
*/
struct page_cgroup {
struct list_head lru; /* per cgroup LRU list */
struct page *page;
struct mem_cgroup *mem_cgroup;
atomic_t ref_cnt; /* Helpful when pages move b/w */
/* mapped and cached states */
int flags;
};
#define PAGE_CGROUP_FLAG_CACHE (0x1) /* charged as cache */
#define PAGE_CGROUP_FLAG_ACTIVE (0x2) /* page is active in this cgroup */
enum {
MEM_CGROUP_TYPE_UNSPEC = 0,
MEM_CGROUP_TYPE_MAPPED,
MEM_CGROUP_TYPE_CACHED,
MEM_CGROUP_TYPE_ALL,
MEM_CGROUP_TYPE_MAX,
};
enum charge_type {
MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
MEM_CGROUP_CHARGE_TYPE_MAPPED,
};
static struct mem_cgroup init_mem_cgroup;
static inline
struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
{
return container_of(cgroup_subsys_state(cont,
mem_cgroup_subsys_id), struct mem_cgroup,
css);
}
static inline
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
{
return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
struct mem_cgroup, css);
}
void mm_init_cgroup(struct mm_struct *mm, struct task_struct *p)
{
struct mem_cgroup *mem;
mem = mem_cgroup_from_task(p);
css_get(&mem->css);
mm->mem_cgroup = mem;
}
void mm_free_cgroup(struct mm_struct *mm)
{
css_put(&mm->mem_cgroup->css);
}
static inline int page_cgroup_locked(struct page *page)
{
return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT,
&page->page_cgroup);
}
void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
{
int locked;
/*
* While resetting the page_cgroup we might not hold the
* page_cgroup lock. free_hot_cold_page() is an example
* of such a scenario
*/
if (pc)
VM_BUG_ON(!page_cgroup_locked(page));
locked = (page->page_cgroup & PAGE_CGROUP_LOCK);
page->page_cgroup = ((unsigned long)pc | locked);
}
struct page_cgroup *page_get_page_cgroup(struct page *page)
{
return (struct page_cgroup *)
(page->page_cgroup & ~PAGE_CGROUP_LOCK);
}
static void __always_inline lock_page_cgroup(struct page *page)
{
bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
VM_BUG_ON(!page_cgroup_locked(page));
}
static void __always_inline unlock_page_cgroup(struct page *page)
{
bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
}
/*
* Tie new page_cgroup to struct page under lock_page_cgroup()
* This can fail if the page has been tied to a page_cgroup.
* If success, returns 0.
*/
static inline int
page_cgroup_assign_new_page_cgroup(struct page *page, struct page_cgroup *pc)
{
int ret = 0;
lock_page_cgroup(page);
if (!page_get_page_cgroup(page))
page_assign_page_cgroup(page, pc);
else /* A page is tied to other pc. */
ret = 1;
unlock_page_cgroup(page);
return ret;
}
/*
* Clear page->page_cgroup member under lock_page_cgroup().
* If given "pc" value is different from one page->page_cgroup,
* page->cgroup is not cleared.
* Returns a value of page->page_cgroup at lock taken.
* A can can detect failure of clearing by following
* clear_page_cgroup(page, pc) == pc
*/
static inline struct page_cgroup *
clear_page_cgroup(struct page *page, struct page_cgroup *pc)
{
struct page_cgroup *ret;
/* lock and clear */
lock_page_cgroup(page);
ret = page_get_page_cgroup(page);
if (likely(ret == pc))
page_assign_page_cgroup(page, NULL);
unlock_page_cgroup(page);
return ret;
}
static void __mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
{
if (active) {
pc->flags |= PAGE_CGROUP_FLAG_ACTIVE;
list_move(&pc->lru, &pc->mem_cgroup->active_list);
} else {
pc->flags &= ~PAGE_CGROUP_FLAG_ACTIVE;
list_move(&pc->lru, &pc->mem_cgroup->inactive_list);
}
}
int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
{
int ret;
task_lock(task);
ret = task->mm && mm_cgroup(task->mm) == mem;
task_unlock(task);
return ret;
}
/*
* This routine assumes that the appropriate zone's lru lock is already held
*/
void mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
{
struct mem_cgroup *mem;
if (!pc)
return;
mem = pc->mem_cgroup;
spin_lock(&mem->lru_lock);
__mem_cgroup_move_lists(pc, active);
spin_unlock(&mem->lru_lock);
}
unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
struct list_head *dst,
unsigned long *scanned, int order,
int mode, struct zone *z,
struct mem_cgroup *mem_cont,
int active)
{
unsigned long nr_taken = 0;
struct page *page;
unsigned long scan;
LIST_HEAD(pc_list);
struct list_head *src;
struct page_cgroup *pc, *tmp;
if (active)
src = &mem_cont->active_list;
else
src = &mem_cont->inactive_list;
spin_lock(&mem_cont->lru_lock);
scan = 0;
list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
if (scan >= nr_to_scan)
break;
page = pc->page;
VM_BUG_ON(!pc);
if (unlikely(!PageLRU(page)))
continue;
if (PageActive(page) && !active) {
__mem_cgroup_move_lists(pc, true);
continue;
}
if (!PageActive(page) && active) {
__mem_cgroup_move_lists(pc, false);
continue;
}
/*
* Reclaim, per zone
* TODO: make the active/inactive lists per zone
*/
if (page_zone(page) != z)
continue;
scan++;
list_move(&pc->lru, &pc_list);
if (__isolate_lru_page(page, mode) == 0) {
list_move(&page->lru, dst);
nr_taken++;
}
}
list_splice(&pc_list, src);
spin_unlock(&mem_cont->lru_lock);
*scanned = scan;
return nr_taken;
}
/*
* Charge the memory controller for page usage.
* Return
* 0 if the charge was successful
* < 0 if the cgroup is over its limit
*/
static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask, enum charge_type ctype)
{
struct mem_cgroup *mem;
struct page_cgroup *pc;
unsigned long flags;
unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
/*
* Should page_cgroup's go to their own slab?
* One could optimize the performance of the charging routine
* by saving a bit in the page_flags and using it as a lock
* to see if the cgroup page already has a page_cgroup associated
* with it
*/
retry:
if (page) {
lock_page_cgroup(page);
pc = page_get_page_cgroup(page);
/*
* The page_cgroup exists and
* the page has already been accounted.
*/
if (pc) {
if (unlikely(!atomic_inc_not_zero(&pc->ref_cnt))) {
/* this page is under being uncharged ? */
unlock_page_cgroup(page);
cpu_relax();
goto retry;
} else {
unlock_page_cgroup(page);
goto done;
}
}
unlock_page_cgroup(page);
}
pc = kzalloc(sizeof(struct page_cgroup), gfp_mask);
if (pc == NULL)
goto err;
/*
* We always charge the cgroup the mm_struct belongs to.
* The mm_struct's mem_cgroup changes on task migration if the
* thread group leader migrates. It's possible that mm is not
* set, if so charge the init_mm (happens for pagecache usage).
*/
if (!mm)
mm = &init_mm;
rcu_read_lock();
mem = rcu_dereference(mm->mem_cgroup);
/*
* For every charge from the cgroup, increment reference
* count
*/
css_get(&mem->css);
rcu_read_unlock();
/*
* If we created the page_cgroup, we should free it on exceeding
* the cgroup limit.
*/
while (res_counter_charge(&mem->res, PAGE_SIZE)) {
if (!(gfp_mask & __GFP_WAIT))
goto out;
if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
continue;
/*
* try_to_free_mem_cgroup_pages() might not give us a full
* picture of reclaim. Some pages are reclaimed and might be
* moved to swap cache or just unmapped from the cgroup.
* Check the limit again to see if the reclaim reduced the
* current usage of the cgroup before giving up
*/
if (res_counter_check_under_limit(&mem->res))
continue;
if (!nr_retries--) {
mem_cgroup_out_of_memory(mem, gfp_mask);
goto out;
}
congestion_wait(WRITE, HZ/10);
}
atomic_set(&pc->ref_cnt, 1);
pc->mem_cgroup = mem;
pc->page = page;
pc->flags = PAGE_CGROUP_FLAG_ACTIVE;
if (ctype == MEM_CGROUP_CHARGE_TYPE_CACHE)
pc->flags |= PAGE_CGROUP_FLAG_CACHE;
if (!page || page_cgroup_assign_new_page_cgroup(page, pc)) {
/*
* Another charge has been added to this page already.
* We take lock_page_cgroup(page) again and read
* page->cgroup, increment refcnt.... just retry is OK.
*/
res_counter_uncharge(&mem->res, PAGE_SIZE);
css_put(&mem->css);
kfree(pc);
if (!page)
goto done;
goto retry;
}
spin_lock_irqsave(&mem->lru_lock, flags);
list_add(&pc->lru, &mem->active_list);
spin_unlock_irqrestore(&mem->lru_lock, flags);
done:
return 0;
out:
css_put(&mem->css);
kfree(pc);
err:
return -ENOMEM;
}
int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask)
{
return mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_MAPPED);
}
/*
* See if the cached pages should be charged at all?
*/
int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask)
{
int ret = 0;
struct mem_cgroup *mem;
if (!mm)
mm = &init_mm;
rcu_read_lock();
mem = rcu_dereference(mm->mem_cgroup);
css_get(&mem->css);
rcu_read_unlock();
if (mem->control_type == MEM_CGROUP_TYPE_ALL)
ret = mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_CACHE);
css_put(&mem->css);
return ret;
}
/*
* Uncharging is always a welcome operation, we never complain, simply
* uncharge.
*/
void mem_cgroup_uncharge(struct page_cgroup *pc)
{
struct mem_cgroup *mem;
struct page *page;
unsigned long flags;
/*
* This can handle cases when a page is not charged at all and we
* are switching between handling the control_type.
*/
if (!pc)
return;
if (atomic_dec_and_test(&pc->ref_cnt)) {
page = pc->page;
/*
* get page->cgroup and clear it under lock.
* force_empty can drop page->cgroup without checking refcnt.
*/
if (clear_page_cgroup(page, pc) == pc) {
mem = pc->mem_cgroup;
css_put(&mem->css);
res_counter_uncharge(&mem->res, PAGE_SIZE);
spin_lock_irqsave(&mem->lru_lock, flags);
list_del_init(&pc->lru);
spin_unlock_irqrestore(&mem->lru_lock, flags);
kfree(pc);
}
}
}
/*
* Returns non-zero if a page (under migration) has valid page_cgroup member.
* Refcnt of page_cgroup is incremented.
*/
int mem_cgroup_prepare_migration(struct page *page)
{
struct page_cgroup *pc;
int ret = 0;
lock_page_cgroup(page);
pc = page_get_page_cgroup(page);
if (pc && atomic_inc_not_zero(&pc->ref_cnt))
ret = 1;
unlock_page_cgroup(page);
return ret;
}
void mem_cgroup_end_migration(struct page *page)
{
struct page_cgroup *pc = page_get_page_cgroup(page);
mem_cgroup_uncharge(pc);
}
/*
* We know both *page* and *newpage* are now not-on-LRU and Pg_locked.
* And no race with uncharge() routines because page_cgroup for *page*
* has extra one reference by mem_cgroup_prepare_migration.
*/
void mem_cgroup_page_migration(struct page *page, struct page *newpage)
{
struct page_cgroup *pc;
retry:
pc = page_get_page_cgroup(page);
if (!pc)
return;
if (clear_page_cgroup(page, pc) != pc)
goto retry;
pc->page = newpage;
lock_page_cgroup(newpage);
page_assign_page_cgroup(newpage, pc);
unlock_page_cgroup(newpage);
return;
}
/*
* This routine traverse page_cgroup in given list and drop them all.
* This routine ignores page_cgroup->ref_cnt.
* *And* this routine doesn't reclaim page itself, just removes page_cgroup.
*/
#define FORCE_UNCHARGE_BATCH (128)
static void
mem_cgroup_force_empty_list(struct mem_cgroup *mem, struct list_head *list)
{
struct page_cgroup *pc;
struct page *page;
int count;
unsigned long flags;
retry:
count = FORCE_UNCHARGE_BATCH;
spin_lock_irqsave(&mem->lru_lock, flags);
while (--count && !list_empty(list)) {
pc = list_entry(list->prev, struct page_cgroup, lru);
page = pc->page;
/* Avoid race with charge */
atomic_set(&pc->ref_cnt, 0);
if (clear_page_cgroup(page, pc) == pc) {
css_put(&mem->css);
res_counter_uncharge(&mem->res, PAGE_SIZE);
list_del_init(&pc->lru);
kfree(pc);
} else /* being uncharged ? ...do relax */
break;
}
spin_unlock_irqrestore(&mem->lru_lock, flags);
if (!list_empty(list)) {
cond_resched();
goto retry;
}
return;
}
/*
* make mem_cgroup's charge to be 0 if there is no task.
* This enables deleting this mem_cgroup.
*/
int mem_cgroup_force_empty(struct mem_cgroup *mem)
{
int ret = -EBUSY;
css_get(&mem->css);
/*
* page reclaim code (kswapd etc..) will move pages between
` * active_list <-> inactive_list while we don't take a lock.
* So, we have to do loop here until all lists are empty.
*/
while (!(list_empty(&mem->active_list) &&
list_empty(&mem->inactive_list))) {
if (atomic_read(&mem->css.cgroup->count) > 0)
goto out;
/* drop all page_cgroup in active_list */
mem_cgroup_force_empty_list(mem, &mem->active_list);
/* drop all page_cgroup in inactive_list */
mem_cgroup_force_empty_list(mem, &mem->inactive_list);
}
ret = 0;
out:
css_put(&mem->css);
return ret;
}
int mem_cgroup_write_strategy(char *buf, unsigned long long *tmp)
{
*tmp = memparse(buf, &buf);
if (*buf != '\0')
return -EINVAL;
/*
* Round up the value to the closest page size
*/
*tmp = ((*tmp + PAGE_SIZE - 1) >> PAGE_SHIFT) << PAGE_SHIFT;
return 0;
}
static ssize_t mem_cgroup_read(struct cgroup *cont,
struct cftype *cft, struct file *file,
char __user *userbuf, size_t nbytes, loff_t *ppos)
{
return res_counter_read(&mem_cgroup_from_cont(cont)->res,
cft->private, userbuf, nbytes, ppos,
NULL);
}
static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
struct file *file, const char __user *userbuf,
size_t nbytes, loff_t *ppos)
{
return res_counter_write(&mem_cgroup_from_cont(cont)->res,
cft->private, userbuf, nbytes, ppos,
mem_cgroup_write_strategy);
}
static ssize_t mem_control_type_write(struct cgroup *cont,
struct cftype *cft, struct file *file,
const char __user *userbuf,
size_t nbytes, loff_t *pos)
{
int ret;
char *buf, *end;
unsigned long tmp;
struct mem_cgroup *mem;
mem = mem_cgroup_from_cont(cont);
buf = kmalloc(nbytes + 1, GFP_KERNEL);
ret = -ENOMEM;
if (buf == NULL)
goto out;
buf[nbytes] = 0;
ret = -EFAULT;
if (copy_from_user(buf, userbuf, nbytes))
goto out_free;
ret = -EINVAL;
tmp = simple_strtoul(buf, &end, 10);
if (*end != '\0')
goto out_free;
if (tmp <= MEM_CGROUP_TYPE_UNSPEC || tmp >= MEM_CGROUP_TYPE_MAX)
goto out_free;
mem->control_type = tmp;
ret = nbytes;
out_free:
kfree(buf);
out:
return ret;
}
static ssize_t mem_control_type_read(struct cgroup *cont,
struct cftype *cft,
struct file *file, char __user *userbuf,
size_t nbytes, loff_t *ppos)
{
unsigned long val;
char buf[64], *s;
struct mem_cgroup *mem;
mem = mem_cgroup_from_cont(cont);
s = buf;
val = mem->control_type;
s += sprintf(s, "%lu\n", val);
return simple_read_from_buffer((void __user *)userbuf, nbytes,
ppos, buf, s - buf);
}
static ssize_t mem_force_empty_write(struct cgroup *cont,
struct cftype *cft, struct file *file,
const char __user *userbuf,
size_t nbytes, loff_t *ppos)
{
struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
int ret;
ret = mem_cgroup_force_empty(mem);
if (!ret)
ret = nbytes;
return ret;
}
/*
* Note: This should be removed if cgroup supports write-only file.
*/
static ssize_t mem_force_empty_read(struct cgroup *cont,
struct cftype *cft,
struct file *file, char __user *userbuf,
size_t nbytes, loff_t *ppos)
{
return -EINVAL;
}
static struct cftype mem_cgroup_files[] = {
{
.name = "usage_in_bytes",
.private = RES_USAGE,
.read = mem_cgroup_read,
},
{
.name = "limit_in_bytes",
.private = RES_LIMIT,
.write = mem_cgroup_write,
.read = mem_cgroup_read,
},
{
.name = "failcnt",
.private = RES_FAILCNT,
.read = mem_cgroup_read,
},
{
.name = "control_type",
.write = mem_control_type_write,
.read = mem_control_type_read,
},
{
.name = "force_empty",
.write = mem_force_empty_write,
.read = mem_force_empty_read,
},
};
static struct mem_cgroup init_mem_cgroup;
static struct cgroup_subsys_state *
mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
{
struct mem_cgroup *mem;
if (unlikely((cont->parent) == NULL)) {
mem = &init_mem_cgroup;
init_mm.mem_cgroup = mem;
} else
mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
if (mem == NULL)
return NULL;
res_counter_init(&mem->res);
INIT_LIST_HEAD(&mem->active_list);
INIT_LIST_HEAD(&mem->inactive_list);
spin_lock_init(&mem->lru_lock);
mem->control_type = MEM_CGROUP_TYPE_ALL;
return &mem->css;
}
static void mem_cgroup_destroy(struct cgroup_subsys *ss,
struct cgroup *cont)
{
kfree(mem_cgroup_from_cont(cont));
}
static int mem_cgroup_populate(struct cgroup_subsys *ss,
struct cgroup *cont)
{
return cgroup_add_files(cont, ss, mem_cgroup_files,
ARRAY_SIZE(mem_cgroup_files));
}
static void mem_cgroup_move_task(struct cgroup_subsys *ss,
struct cgroup *cont,
struct cgroup *old_cont,
struct task_struct *p)
{
struct mm_struct *mm;
struct mem_cgroup *mem, *old_mem;
mm = get_task_mm(p);
if (mm == NULL)
return;
mem = mem_cgroup_from_cont(cont);
old_mem = mem_cgroup_from_cont(old_cont);
if (mem == old_mem)
goto out;
/*
* Only thread group leaders are allowed to migrate, the mm_struct is
* in effect owned by the leader
*/
if (p->tgid != p->pid)
goto out;
css_get(&mem->css);
rcu_assign_pointer(mm->mem_cgroup, mem);
css_put(&old_mem->css);
out:
mmput(mm);
return;
}
struct cgroup_subsys mem_cgroup_subsys = {
.name = "memory",
.subsys_id = mem_cgroup_subsys_id,
.create = mem_cgroup_create,
.destroy = mem_cgroup_destroy,
.populate = mem_cgroup_populate,
.attach = mem_cgroup_move_task,
.early_init = 1,
};