Commit b5a84319 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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memcg: fix shmem's swap accounting



Now, you can see following even when swap accounting is enabled.

 1. Create Group 01, and 02.
 2. allocate a "file" on tmpfs by a task under 01.
 3. swap out the "file" (by memory pressure)
 4. Read "file" from a task in group 02.
 5. the charge of "file" is moved to group 02.

This is not ideal behavior. This is because SwapCache which was loaded
by read-ahead is not taken into account..

This is a patch to fix shmem's swapcache behavior.
  - remove mem_cgroup_cache_charge_swapin().
  - Add SwapCache handler routine to mem_cgroup_cache_charge().
    By this, shmem's file cache is charged at add_to_page_cache()
    with GFP_NOWAIT.
  - pass the page of swapcache to shrink_mem_cgroup.
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 544122e5
......@@ -56,7 +56,8 @@ extern void mem_cgroup_move_lists(struct page *page,
enum lru_list from, enum lru_list to);
extern void mem_cgroup_uncharge_page(struct page *page);
extern void mem_cgroup_uncharge_cache_page(struct page *page);
extern int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask);
extern int mem_cgroup_shrink_usage(struct page *page,
struct mm_struct *mm, gfp_t gfp_mask);
extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
struct list_head *dst,
......@@ -155,7 +156,8 @@ static inline void mem_cgroup_uncharge_cache_page(struct page *page)
{
}
static inline int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
static inline int mem_cgroup_shrink_usage(struct page *page,
struct mm_struct *mm, gfp_t gfp_mask)
{
return 0;
}
......
......@@ -335,16 +335,8 @@ static inline void disable_swap_token(void)
}
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
extern int mem_cgroup_cache_charge_swapin(struct page *page,
struct mm_struct *mm, gfp_t mask, bool locked);
extern void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent);
#else
static inline
int mem_cgroup_cache_charge_swapin(struct page *page,
struct mm_struct *mm, gfp_t mask, bool locked)
{
return 0;
}
static inline void
mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
{
......
......@@ -893,6 +893,23 @@ nomem:
return -ENOMEM;
}
static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
{
struct mem_cgroup *mem;
swp_entry_t ent;
if (!PageSwapCache(page))
return NULL;
ent.val = page_private(page);
mem = lookup_swap_cgroup(ent);
if (!mem)
return NULL;
if (!css_tryget(&mem->css))
return NULL;
return mem;
}
/*
* commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be
* USED state. If already USED, uncharge and return.
......@@ -1084,6 +1101,9 @@ int mem_cgroup_newpage_charge(struct page *page,
int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask)
{
struct mem_cgroup *mem = NULL;
int ret;
if (mem_cgroup_disabled())
return 0;
if (PageCompound(page))
......@@ -1096,6 +1116,8 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
* For GFP_NOWAIT case, the page may be pre-charged before calling
* add_to_page_cache(). (See shmem.c) check it here and avoid to call
* charge twice. (It works but has to pay a bit larger cost.)
* And when the page is SwapCache, it should take swap information
* into account. This is under lock_page() now.
*/
if (!(gfp_mask & __GFP_WAIT)) {
struct page_cgroup *pc;
......@@ -1112,15 +1134,40 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
unlock_page_cgroup(pc);
}
if (unlikely(!mm))
if (do_swap_account && PageSwapCache(page)) {
mem = try_get_mem_cgroup_from_swapcache(page);
if (mem)
mm = NULL;
else
mem = NULL;
/* SwapCache may be still linked to LRU now. */
mem_cgroup_lru_del_before_commit_swapcache(page);
}
if (unlikely(!mm && !mem))
mm = &init_mm;
if (page_is_file_cache(page))
return mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
else
return mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_SHMEM, NULL);
ret = mem_cgroup_charge_common(page, mm, gfp_mask,
MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
if (mem)
css_put(&mem->css);
if (PageSwapCache(page))
mem_cgroup_lru_add_after_commit_swapcache(page);
if (do_swap_account && !ret && PageSwapCache(page)) {
swp_entry_t ent = {.val = page_private(page)};
/* avoid double counting */
mem = swap_cgroup_record(ent, NULL);
if (mem) {
res_counter_uncharge(&mem->memsw, PAGE_SIZE);
mem_cgroup_put(mem);
}
}
return ret;
}
/*
......@@ -1134,7 +1181,6 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
gfp_t mask, struct mem_cgroup **ptr)
{
struct mem_cgroup *mem;
swp_entry_t ent;
int ret;
if (mem_cgroup_disabled())
......@@ -1142,7 +1188,6 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
if (!do_swap_account)
goto charge_cur_mm;
/*
* A racing thread's fault, or swapoff, may have already updated
* the pte, and even removed page from swap cache: return success
......@@ -1150,14 +1195,9 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
*/
if (!PageSwapCache(page))
return 0;
ent.val = page_private(page);
mem = lookup_swap_cgroup(ent);
mem = try_get_mem_cgroup_from_swapcache(page);
if (!mem)
goto charge_cur_mm;
if (!css_tryget(&mem->css))
goto charge_cur_mm;
*ptr = mem;
ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
/* drop extra refcnt from tryget */
......@@ -1169,62 +1209,6 @@ charge_cur_mm:
return __mem_cgroup_try_charge(mm, mask, ptr, true);
}
#ifdef CONFIG_SWAP
int mem_cgroup_cache_charge_swapin(struct page *page,
struct mm_struct *mm, gfp_t mask, bool locked)
{
int ret = 0;
if (mem_cgroup_disabled())
return 0;
if (unlikely(!mm))
mm = &init_mm;
if (!locked)
lock_page(page);
/*
* If not locked, the page can be dropped from SwapCache until
* we reach here.
*/
if (PageSwapCache(page)) {
struct mem_cgroup *mem = NULL;
swp_entry_t ent;
ent.val = page_private(page);
if (do_swap_account) {
mem = lookup_swap_cgroup(ent);
if (mem) {
if (css_tryget(&mem->css))
mm = NULL; /* charge to recorded */
else
mem = NULL; /* charge to current */
}
}
/* SwapCache may be still linked to LRU now. */
mem_cgroup_lru_del_before_commit_swapcache(page);
ret = mem_cgroup_charge_common(page, mm, mask,
MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
mem_cgroup_lru_add_after_commit_swapcache(page);
/* drop extra refcnt from tryget */
if (mem)
css_put(&mem->css);
if (!ret && do_swap_account) {
/* avoid double counting */
mem = swap_cgroup_record(ent, NULL);
if (mem) {
res_counter_uncharge(&mem->memsw, PAGE_SIZE);
mem_cgroup_put(mem);
}
}
}
if (!locked)
unlock_page(page);
return ret;
}
#endif
void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
{
struct page_cgroup *pc;
......@@ -1486,18 +1470,20 @@ void mem_cgroup_end_migration(struct mem_cgroup *mem,
* This is typically used for page reclaiming for shmem for reducing side
* effect of page allocation from shmem, which is used by some mem_cgroup.
*/
int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
int mem_cgroup_shrink_usage(struct page *page,
struct mm_struct *mm,
gfp_t gfp_mask)
{
struct mem_cgroup *mem;
struct mem_cgroup *mem = NULL;
int progress = 0;
int retry = MEM_CGROUP_RECLAIM_RETRIES;
if (mem_cgroup_disabled())
return 0;
if (!mm)
return 0;
mem = try_get_mem_cgroup_from_mm(mm);
if (page)
mem = try_get_mem_cgroup_from_swapcache(page);
if (!mem && mm)
mem = try_get_mem_cgroup_from_mm(mm);
if (unlikely(!mem))
return 0;
......
......@@ -929,11 +929,11 @@ found:
if (!inode)
goto out;
/*
* Charge page using GFP_HIGHUSER_MOVABLE while we can wait.
* charged back to the user(not to caller) when swap account is used.
* Charge page using GFP_KERNEL while we can wait.
* Charged back to the user(not to caller) when swap account is used.
* add_to_page_cache() will be called with GFP_NOWAIT.
*/
error = mem_cgroup_cache_charge_swapin(page, current->mm, GFP_KERNEL,
true);
error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
if (error)
goto out;
error = radix_tree_preload(GFP_KERNEL);
......@@ -1270,16 +1270,6 @@ repeat:
goto repeat;
}
wait_on_page_locked(swappage);
/*
* We want to avoid charge at add_to_page_cache().
* charge against this swap cache here.
*/
if (mem_cgroup_cache_charge_swapin(swappage,
current->mm, gfp & GFP_RECLAIM_MASK, false)) {
page_cache_release(swappage);
error = -ENOMEM;
goto failed;
}
page_cache_release(swappage);
goto repeat;
}
......@@ -1334,15 +1324,19 @@ repeat:
} else {
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
unlock_page(swappage);
page_cache_release(swappage);
if (error == -ENOMEM) {
/* allow reclaim from this memory cgroup */
error = mem_cgroup_shrink_usage(current->mm,
error = mem_cgroup_shrink_usage(swappage,
current->mm,
gfp);
if (error)
if (error) {
unlock_page(swappage);
page_cache_release(swappage);
goto failed;
}
}
unlock_page(swappage);
page_cache_release(swappage);
goto repeat;
}
} else if (sgp == SGP_READ && !filepage) {
......
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