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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: mhocko@suse.com
Cc: linux-mm@kvack.org, rientjes@google.com
Subject: Re: [PATCH 1/2] mm,oom_reaper: Show trace of unable to reap victim thread.
Date: Tue, 20 Mar 2018 22:30:16 +0900	[thread overview]
Message-ID: <201803202230.HDH17140.OFtMQJVLOOFHSF@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20180320131953.GM23100@dhcp22.suse.cz>

Michal Hocko wrote:
> On Tue 20-03-18 21:52:33, Tetsuo Handa wrote:
> > Michal Hocko wrote:
> > > A single stack trace in the changelog would be sufficient IMHO.
> > > Appart from that. What do you expect users will do about this trace?
> > > Sure they will see a path which holds mmap_sem, we will see a bug report
> > > but we can hardly do anything about that. We simply cannot drop the lock
> > > from that path in 99% of situations. So _why_ do we want to add more
> > > information to the log?
> > 
> > This case is blocked at i_mmap_lock_write().
> 
> But why does i_mmap_lock_write matter for oom_reaping. We are not
> touching hugetlb mappings. dup_mmap holds mmap_sem for write which is
> the most probable source of the backoff.

If i_mmap_lock_write can bail out upon SIGKILL, the OOM victim will be able to
release mmap_sem held for write, which helps the OOM reaper not to back off.

  reply	other threads:[~2018-03-20 13:30 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-20 11:57 [PATCH 1/2] mm,oom_reaper: Show trace of unable to reap victim thread Tetsuo Handa
2018-03-20 11:57 ` [PATCH 2/2] mm,oom_reaper: Correct MAX_OOM_REAP_RETRIES'th attempt Tetsuo Handa
2018-03-20 12:12   ` Michal Hocko
2018-03-20 12:37     ` Tetsuo Handa
2018-03-20 12:47       ` [PATCH 2/2] mm,oom_reaper: Check for MMF_OOM_SKIP before complain Tetsuo Handa
2018-03-20 20:49         ` David Rientjes
2018-03-22 10:46           ` [PATCH] " Tetsuo Handa
2018-03-22 11:59             ` Michal Hocko
2018-03-20 13:24       ` [PATCH 2/2] mm,oom_reaper: Correct MAX_OOM_REAP_RETRIES'th attempt Michal Hocko
2018-03-20 13:37         ` Tetsuo Handa
2018-03-20 13:44           ` Michal Hocko
2018-03-20 12:28 ` [PATCH 1/2] mm,oom_reaper: Show trace of unable to reap victim thread Michal Hocko
2018-03-20 12:52   ` Tetsuo Handa
2018-03-20 13:19     ` Michal Hocko
2018-03-20 13:30       ` Tetsuo Handa [this message]
2018-03-20 13:34         ` Michal Hocko
2018-03-20 13:50           ` Tetsuo Handa
2018-03-20 14:10             ` Michal Hocko
2018-03-20 14:20               ` Tetsuo Handa
2018-03-20 20:46                 ` David Rientjes

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