Commit 8dc87c7d authored by Muchun Song's avatar Muchun Song Committed by Linus Torvalds
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mm: memcontrol: fix page charging in page replacement 

Patch series "memcontrol code cleanup and simplification", v3.

This patch (of 8):

The pages aren't accounted at the root level, so do not charge the page to
the root memcg in page replacement.  Although we do not display the value
(mem_cgroup_usage) so there shouldn't be any actual problem, but there is
a WARN_ON_ONCE in the page_counter_cancel().  Who knows if it will
trigger?  So it is better to fix it.

Link: https://lkml.kernel.org/r/20210417043538.9793-1-songmuchun@bytedance.com
Link: https://lkml.kernel.org/r/20210417043538.9793-2-songmuchun@bytedance.com


Signed-off-by: default avatarMuchun Song <songmuchun@bytedance.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c5c8b16b

mm/memcontrol.c

+5 −3
Original line number Diff line number Diff line
@@ -6984,9 +6984,11 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage) 
	/* Force-charge the new page. The old one will be freed soon */

	nr_pages = thp_nr_pages(newpage);



	if (!mem_cgroup_is_root(memcg)) {

		page_counter_charge(&memcg->memory, nr_pages);

		if (do_memsw_account())

			page_counter_charge(&memcg->memsw, nr_pages);

	}



	css_get(&memcg->css);

	commit_charge(newpage, memcg);