From: Yosry Ahmed <yosryahmed@google.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Liu Shixin <liushixin2@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeelb@google.com>,
Muchun Song <muchun.song@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
wangkefeng.wang@huawei.com, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2] mm: vmscan: reclaim anon pages if there are swapcache pages
Date: Wed, 23 Aug 2023 08:29:19 -0700 [thread overview]
Message-ID: <CAJD7tkYivogrRtAx8a+EPfjRqQNgoOZFZyG8rC91E_hW6pdTEw@mail.gmail.com> (raw)
In-Reply-To: <ZOYFydIp3q8BNrEa@dhcp22.suse.cz>
On Wed, Aug 23, 2023 at 6:12 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Wed 23-08-23 10:00:58, Liu Shixin wrote:
> >
> >
> > On 2023/8/23 0:35, Yosry Ahmed wrote:
> > > On Mon, Aug 21, 2023 at 6:54 PM Liu Shixin <liushixin2@huawei.com> wrote:
> > >> When spaces of swap devices are exhausted, only file pages can be reclaimed.
> > >> But there are still some swapcache pages in anon lru list. This can lead
> > >> to a premature out-of-memory.
> > >>
> > >> This problem can be fixed by checking number of swapcache pages in
> > >> can_reclaim_anon_pages(). For memcg v2, there are swapcache stat that can
> > >> be used directly. For memcg v1, use total_swapcache_pages() instead, which
> > >> may not accurate but can solve the problem.
> > > Interesting find. I wonder if we really don't have any handling of
> > > this situation.
> > I have alreadly test this problem and can confirm that it is a real problem.
> > With 9MB swap space and 10MB mem_cgroup limit，when allocate 15MB memory,
> > there is a probability that OOM occurs.
>
> Could you be more specific about the test and the oom report?
I actually couldn't reproduce it using 9MB of zram and a cgroup with a
10MB limit trying to allocate 15MB of tmpfs, no matter how many
repetitions I do.
>
> --
> Michal Hocko
> SUSE Labs
next prev parent reply other threads:[~2023-08-23 15:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-22 2:49 [PATCH v2] mm: vmscan: reclaim anon pages if there are swapcache pages Liu Shixin
2023-08-22 16:35 ` Yosry Ahmed
2023-08-23 2:00 ` Liu Shixin
2023-08-23 13:12 ` Michal Hocko
2023-08-23 15:29 ` Yosry Ahmed [this message]
2023-08-24 3:39 ` Liu Shixin
2023-08-24 18:27 ` Yosry Ahmed
2023-08-24 8:48 ` Huang, Ying
2023-08-24 18:31 ` Yosry Ahmed
2023-08-25 0:47 ` Huang, Ying
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