From: David Rientjes <rientjes@google.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: syzbot <syzbot+77e6b28a7a7106ad0def@syzkaller.appspotmail.com>,
hannes@cmpxchg.org, mhocko@kernel.org, akpm@linux-foundation.org,
guro@fb.com, kirill.shutemov@linux.intel.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
syzkaller-bugs@googlegroups.com, yang.s@alibaba-inc.com
Subject: Re: INFO: rcu detected stall in shmem_fault
Date: Tue, 9 Oct 2018 21:11:48 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.1810092106190.83503@chino.kir.corp.google.com> (raw)
In-Reply-To: <201810100012.w9A0Cjtn047782@www262.sakura.ne.jp>
On Wed, 10 Oct 2018, Tetsuo Handa wrote:
> syzbot is hitting RCU stall due to memcg-OOM event.
> https://syzkaller.appspot.com/bug?id=4ae3fff7fcf4c33a47c1192d2d62d2e03efffa64
>
> What should we do if memcg-OOM found no killable task because the allocating task
> was oom_score_adj == -1000 ? Flooding printk() until RCU stall watchdog fires
> (which seems to be caused by commit 3100dab2aa09dc6e ("mm: memcontrol: print proper
> OOM header when no eligible victim left") because syzbot was terminating the test
> upon WARN(1) removed by that commit) is not a good behavior.
>
Not printing anything would be the obvious solution but the ideal solution
would probably involve
- adding feedback to the memcg oom killer that there are no killable
processes,
- adding complete coverage for memcg_oom_recover() in all uncharge paths
where the oom memcg's page_counter is decremented, and
- having all processes stall until memcg_oom_recover() is called so
looping back into try_charge() has a reasonable expectation to succeed.
next prev parent reply other threads:[~2018-10-10 4:12 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 0:08 INFO: rcu detected stall in shmem_fault syzbot
2018-10-10 0:12 ` Tetsuo Handa
2018-10-10 4:11 ` David Rientjes [this message]
2018-10-10 7:55 ` Dmitry Vyukov
2018-10-10 9:13 ` Michal Hocko
2018-10-10 9:33 ` Dmitry Vyukov
2018-10-10 9:02 ` Michal Hocko
2018-10-10 8:59 ` Michal Hocko
2018-10-10 10:43 ` Tetsuo Handa
2018-10-10 11:35 ` Michal Hocko
2018-10-10 11:48 ` Sergey Senozhatsky
2018-10-10 12:25 ` Michal Hocko
2018-10-10 12:29 ` Dmitry Vyukov
2018-10-10 12:36 ` Dmitry Vyukov
2018-10-10 13:10 ` Tetsuo Handa
2018-10-10 13:17 ` Dmitry Vyukov
2018-10-11 1:17 ` Sergey Senozhatsky
2018-10-10 15:17 ` Sergey Senozhatsky
2018-10-10 14:19 ` Tetsuo Handa
2018-10-10 15:11 ` [RFC PATCH] memcg, oom: throttle dump_header for memcg ooms without eligible tasks Michal Hocko
2018-10-11 6:37 ` Tetsuo Handa
2018-10-12 10:47 ` Tetsuo Handa
2018-10-12 11:20 ` Johannes Weiner
2018-10-12 12:08 ` Michal Hocko
2018-10-12 12:10 ` Tetsuo Handa
2018-10-12 12:41 ` Johannes Weiner
2018-10-12 12:58 ` Tetsuo Handa
2018-10-13 11:09 ` Tetsuo Handa
2018-10-13 11:22 ` Johannes Weiner
2018-10-13 11:28 ` Tetsuo Handa
2018-10-15 8:19 ` Michal Hocko
2018-10-15 10:57 ` Tetsuo Handa
2018-10-15 11:24 ` Michal Hocko
2018-10-15 12:47 ` Tetsuo Handa
2018-10-15 13:35 ` Michal Hocko
2018-10-16 0:55 ` Tetsuo Handa
2018-10-16 9:20 ` Michal Hocko
2018-10-16 11:05 ` Tetsuo Handa
2018-10-16 11:17 ` Michal Hocko
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