提交 c0bd3f63 编写于 作者: D Daisuke Nishimura 提交者: Linus Torvalds

memcg: fix try_get_mem_cgroup_from_swapcache()

This is a bugfix for commit 3c776e64
("memcg: charge swapcache to proper memcg").

Used bit of swapcache is solid under page lock, but considering
move_account, pc->mem_cgroup is not.

We need lock_page_cgroup() anyway.
Signed-off-by: NDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 1e50cc90
...@@ -1024,9 +1024,7 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page) ...@@ -1024,9 +1024,7 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
return NULL; return NULL;
pc = lookup_page_cgroup(page); pc = lookup_page_cgroup(page);
/* lock_page_cgroup(pc);
* Used bit of swapcache is solid under page lock.
*/
if (PageCgroupUsed(pc)) { if (PageCgroupUsed(pc)) {
mem = pc->mem_cgroup; mem = pc->mem_cgroup;
if (mem && !css_tryget(&mem->css)) if (mem && !css_tryget(&mem->css))
...@@ -1040,6 +1038,7 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page) ...@@ -1040,6 +1038,7 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
mem = NULL; mem = NULL;
rcu_read_unlock(); rcu_read_unlock();
} }
unlock_page_cgroup(pc);
return mem; return mem;
} }
......
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