Messages in this thread | | | Date | Mon, 15 Feb 2021 10:47:54 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH 4/4] mm: memcontrol: fix swap uncharge on cgroup v2 |
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On Sat 13-02-21 01:01:59, Muchun Song wrote: > The swap charges the actual number of swap entries on cgroup v2. > If a swap cache page is charged successful, and then we uncharge > the swap counter. It is wrong on cgroup v2. Because the swap > entry is not freed.
Is there any actual problem though? Can you describe the specific scenario please? Swap cache charge life time is a bit tricky and I have to confess I have to relearn it every time I need to understand it. The patch would be much more easier to review if the changelog was much more specific.
> Fixes: 2d1c498072de ("mm: memcontrol: make swap tracking an integral part of memory control") > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > --- > mm/memcontrol.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index c737c8f05992..be6bc5044150 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -6753,7 +6753,7 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) > memcg_check_events(memcg, page); > local_irq_enable(); > > - if (PageSwapCache(page)) { > + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && PageSwapCache(page)) { > swp_entry_t entry = { .val = page_private(page) }; > /* > * The swap entry might not get freed for a long time, > -- > 2.11.0
-- Michal Hocko SUSE Labs
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