memcg: fix try_get_mem_cgroup_from_swapcache()
This is a bugfix for commit 3c776e6466
("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: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
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@ -1024,9 +1024,7 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
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return NULL;
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pc = lookup_page_cgroup(page);
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/*
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* Used bit of swapcache is solid under page lock.
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*/
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lock_page_cgroup(pc);
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if (PageCgroupUsed(pc)) {
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mem = pc->mem_cgroup;
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if (mem && !css_tryget(&mem->css))
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@ -1040,6 +1038,7 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
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mem = NULL;
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rcu_read_unlock();
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}
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unlock_page_cgroup(pc);
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return mem;
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}
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