memcg: fix kmem_account_flags check in memcg_can_account_kmem()
We should start kmem accounting for a memory cgroup only after both its kmem limit is set (KMEM_ACCOUNTED_ACTIVE) and related call sites are patched (KMEM_ACCOUNTED_ACTIVATED). Currently memcg_can_account_kmem() allows kmem accounting even if only one of the conditions is true. Fix it. This means that a page might get charged by memcg_kmem_newpage_charge which would see its static key patched already but memcg_kmem_commit_charge would still see it unpatched and so the charge won't be committed. The result would be charge inconsistency (page_cgroup not marked as PageCgroupUsed) and the charge would leak because __memcg_kmem_uncharge_pages would ignore it. [mhocko@suse.cz: augment changelog] Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -2959,7 +2959,8 @@ static DEFINE_MUTEX(set_limit_mutex);
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static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
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{
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return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) &&
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(memcg->kmem_account_flags & KMEM_ACCOUNTED_MASK);
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(memcg->kmem_account_flags & KMEM_ACCOUNTED_MASK) ==
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KMEM_ACCOUNTED_MASK;
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}
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/*
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