From: Michal Hocko <mhocko@suse.com>
To: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <guro@fb.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
Shakeel Butt <shakeelb@google.com>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [PATCH] mm: memcontrol: fix memsw uncharge for root_mem_cgroup
Date: Wed, 24 Mar 2021 09:33:14 +0100 [thread overview]
Message-ID: <YFr5SrJ2iNGYwVNA@dhcp22.suse.cz> (raw)
In-Reply-To: <CAMZfGtWT8XXDtg0Jcv=1qJpdLD6foJWE=kB_i1ZyHjvrku=vrw@mail.gmail.com>
On Wed 24-03-21 12:11:35, Muchun Song wrote:
> On Tue, Mar 23, 2021 at 11:04 PM Muchun Song <songmuchun@bytedance.com> wrote:
> >
> > The pages aren't accounted at the root level, so we cannot uncharge the
> > page to the memsw counter for the root memcg. Fix this.
> >
> > Fixes: 1f47b61fb407 ("mm: memcontrol: fix swap counter leak on swapout from offline cgroup")
> > Signed-off-by: Muchun Song <songmuchun@bytedance.com>
>
> I am very sorry. I should repent. I suddenly realise the fix is totally
> wrong. Because the @memcg cannot be root memcg when
> @memcg != @swap_memcg.
I am probably blind but I do not see why this would be the case.
We have memcg != swap_memcg in this branch but we do not know the
neither of the two is root_mem_cgroup, no? If we did knot that we
wouldn't have to check for swap_memcg != root_mem_cgroup. Or do I miss
something?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-03-24 8:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 14:56 [PATCH] mm: memcontrol: fix memsw uncharge for root_mem_cgroup Muchun Song
2021-03-23 16:11 ` Michal Hocko
2021-03-24 4:11 ` Muchun Song
2021-03-24 4:11 ` Muchun Song
2021-03-24 8:33 ` Michal Hocko [this message]
2021-03-24 8:50 ` [External] " Muchun Song
2021-03-24 8:50 ` Muchun Song
2021-03-24 9:20 ` Michal Hocko
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