Commit 50de1dd9 authored by Daisuke Nishimura's avatar Daisuke Nishimura Committed by Linus Torvalds

memcg: fix memory migration of shmem swapcache

In the current implementation mem_cgroup_end_migration() decides whether
the page migration has succeeded or not by checking "oldpage->mapping".

But if we are tring to migrate a shmem swapcache, the page->mapping of it
is NULL from the begining, so the check would be invalid.  As a result,
mem_cgroup_end_migration() assumes the migration has succeeded even if
it's not, so "newpage" would be freed while it's not uncharged.

This patch fixes it by passing mem_cgroup_end_migration() the result of
the page migration.
Signed-off-by: default avatarDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: default avatarBalbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 17295c88
......@@ -98,7 +98,7 @@ extern int
mem_cgroup_prepare_migration(struct page *page,
struct page *newpage, struct mem_cgroup **ptr);
extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
struct page *oldpage, struct page *newpage);
struct page *oldpage, struct page *newpage, bool migration_ok);
/*
* For memory reclaim.
......@@ -251,8 +251,7 @@ mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
}
static inline void mem_cgroup_end_migration(struct mem_cgroup *mem,
struct page *oldpage,
struct page *newpage)
struct page *oldpage, struct page *newpage, bool migration_ok)
{
}
......
......@@ -2896,7 +2896,7 @@ int mem_cgroup_prepare_migration(struct page *page,
/* remove redundant charge if migration failed*/
void mem_cgroup_end_migration(struct mem_cgroup *mem,
struct page *oldpage, struct page *newpage)
struct page *oldpage, struct page *newpage, bool migration_ok)
{
struct page *used, *unused;
struct page_cgroup *pc;
......@@ -2905,8 +2905,7 @@ void mem_cgroup_end_migration(struct mem_cgroup *mem,
return;
/* blocks rmdir() */
cgroup_exclude_rmdir(&mem->css);
/* at migration success, oldpage->mapping is NULL. */
if (oldpage->mapping) {
if (!migration_ok) {
used = oldpage;
unused = newpage;
} else {
......
......@@ -768,7 +768,7 @@ skip_unmap:
uncharge:
if (!charge)
mem_cgroup_end_migration(mem, page, newpage);
mem_cgroup_end_migration(mem, page, newpage, rc == 0);
unlock:
unlock_page(page);
......
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