From 8dc87c7d1fec8851925ca96ade0d65d3dcf89cce Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Mon, 28 Jun 2021 19:37:47 -0700 Subject: 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: Muchun Song Acked-by: Johannes Weiner Reviewed-by: Shakeel Butt Acked-by: Roman Gushchin Acked-by: Michal Hocko Cc: Vladimir Davydov Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 70690fdf53cc..239f69ed1ac1 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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); - page_counter_charge(&memcg->memory, nr_pages); - if (do_memsw_account()) - page_counter_charge(&memcg->memsw, nr_pages); + 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); -- cgit