From: Andrew Morton <akpm@linux-foundation.org>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Shakeel Butt <shakeelb@google.com>
Subject: Re: [PATCH v4] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes
Date: Wed, 10 Jan 2018 14:31:21 -0800 [thread overview]
Message-ID: <20180110143121.cf2a1c5497b31642c9b38b2a@linux-foundation.org> (raw)
In-Reply-To: <20180110124317.28887-1-aryabinin@virtuozzo.com>
On Wed, 10 Jan 2018 15:43:17 +0300 Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
> mem_cgroup_resize_[memsw]_limit() tries to free only 32 (SWAP_CLUSTER_MAX)
> pages on each iteration. This makes practically impossible to decrease
> limit of memory cgroup. Tasks could easily allocate back 32 pages,
> so we can't reduce memory usage, and once retry_count reaches zero we return
> -EBUSY.
>
> Easy to reproduce the problem by running the following commands:
>
> mkdir /sys/fs/cgroup/memory/test
> echo $$ >> /sys/fs/cgroup/memory/test/tasks
> cat big_file > /dev/null &
> sleep 1 && echo $((100*1024*1024)) > /sys/fs/cgroup/memory/test/memory.limit_in_bytes
> -bash: echo: write error: Device or resource busy
>
> Instead of relying on retry_count, keep retrying the reclaim until
> the desired limit is reached or fail if the reclaim doesn't make
> any progress or a signal is pending.
>
Is there any situation under which that mem_cgroup_resize_limit() can
get stuck semi-indefinitely in a livelockish state? It isn't very
obvious that we're protected from this, so perhaps it would help to
have a comment which describes how loop termination is assured?
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next prev parent reply other threads:[~2018-01-10 22:31 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-20 10:24 [PATCH 1/2] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes Andrey Ryabinin
2017-12-20 10:24 ` [PATCH 2/2] mm/memcg: Consolidate mem_cgroup_resize_[memsw]_limit() functions Andrey Ryabinin
2017-12-20 10:33 ` [PATCH 1/2] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes Michal Hocko
2017-12-20 11:32 ` Andrey Ryabinin
2017-12-20 11:34 ` Michal Hocko
2017-12-20 18:15 ` Shakeel Butt
2017-12-21 10:00 ` Andrey Ryabinin
2017-12-20 13:21 ` [PATCH v2 " Andrey Ryabinin
2017-12-20 13:21 ` [PATCH v2 2/2] mm/memcg: Consolidate mem_cgroup_resize_[memsw]_limit() functions Andrey Ryabinin
2017-12-20 13:53 ` [PATCH v2 1/2] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes Michal Hocko
2018-01-09 16:58 ` [PATCH v3 " Andrey Ryabinin
2018-01-09 16:58 ` [PATCH v3 2/2] mm/memcg: Consolidate mem_cgroup_resize_[memsw]_limit() functions Andrey Ryabinin
2018-01-09 17:10 ` Shakeel Butt
2018-01-09 17:26 ` Andrey Ryabinin
2018-01-09 23:26 ` Andrew Morton
2018-01-10 12:43 ` [PATCH v4] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes Andrey Ryabinin
2018-01-10 22:31 ` Andrew Morton [this message]
2018-01-11 11:59 ` Andrey Ryabinin
2018-01-12 0:21 ` Andrew Morton
2018-01-12 9:08 ` Andrey Ryabinin
2018-01-11 10:42 ` Michal Hocko
2018-01-11 12:21 ` Andrey Ryabinin
2018-01-11 12:46 ` Michal Hocko
2018-01-11 15:23 ` Andrey Ryabinin
2018-01-11 16:29 ` Michal Hocko
2018-01-11 21:59 ` Andrey Ryabinin
2018-01-12 12:24 ` Michal Hocko
2018-01-12 22:57 ` Shakeel Butt
2018-01-15 12:29 ` Andrey Ryabinin
2018-01-15 17:04 ` Shakeel Butt
2018-01-15 12:30 ` Andrey Ryabinin
2018-01-15 12:46 ` Michal Hocko
2018-01-15 12:53 ` Andrey Ryabinin
2018-01-15 12:58 ` Michal Hocko
2018-01-09 17:08 ` [PATCH v3 1/2] " Andrey Ryabinin
2018-01-09 17:22 ` Shakeel Butt
2018-01-19 13:25 ` [PATCH v5 1/2] mm/memcontrol.c: " Andrey Ryabinin
2018-01-19 13:25 ` [PATCH v5 2/2] mm/memcontrol.c: Reduce reclaim retries in mem_cgroup_resize_limit() Andrey Ryabinin
2018-01-19 13:35 ` Michal Hocko
2018-01-19 14:49 ` Shakeel Butt
2018-01-19 15:11 ` Michal Hocko
2018-01-19 15:24 ` Shakeel Butt
2018-01-19 15:31 ` Michal Hocko
2018-02-21 20:17 ` Andrew Morton
2018-02-22 13:50 ` Andrey Ryabinin
2018-02-22 14:09 ` Michal Hocko
2018-02-22 15:13 ` Andrey Ryabinin
2018-02-22 15:33 ` Michal Hocko
2018-02-22 15:38 ` Andrey Ryabinin
2018-02-22 15:44 ` Michal Hocko
2018-02-22 16:01 ` Andrey Ryabinin
2018-02-22 16:30 ` Michal Hocko
2018-01-19 13:32 ` [PATCH v5 1/2] mm/memcontrol.c: try harder to decrease [memory,memsw].limit_in_bytes Michal Hocko
2018-01-25 19:44 ` Andrey Ryabinin
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