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From: Michal Hocko <mhocko@kernel.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	linux-mm@kvack.org, Greg Thelen <gthelen@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	David Rientjes <rientjes@google.com>
Subject: Re: [PATCH] memcg, oom: be careful about races when warning about no reclaimable task
Date: Wed, 8 Aug 2018 15:16:58 +0200	[thread overview]
Message-ID: <20180808131658.GP27972@dhcp22.suse.cz> (raw)
In-Reply-To: <9cea37c8-ab90-2fdf-395c-efe52ff07072@i-love.sakura.ne.jp>

On Wed 08-08-18 21:57:13, Tetsuo Handa wrote:
[...]
> Also, before the OOM reaper was introduced, we waited until TIF_MEMDIE is
> cleared from the OOM victim thread. Compared to pre OOM reaper era, giving up
> so early is certainly a regression.

We did clear TIF_MEMDIE flag after mmput() in do_exit so this was not a silver
bullet either. Any reference on the mm_struct would lead to a similar
problem. So could you please stop making strong stamements and start
being reasonable?

Yeah, this is racy. Nobody is claiming otherwise. All we are trying to
say is that this area is full of dragons and before we start making it
more complicating by covering weird cornercases we really need to see
that those corner cases happen in real workloads. Otherwise we end up
with a unmaintainable and fragile mess.

And more importantly this is _not_ what this patch is trying to address
so please do not go tangent again.

I really do not know how to send this simply message to you. I have
tried so many times before.

-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2018-08-08 13:17 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-07  7:25 [PATCH] memcg, oom: be careful about races when warning about no reclaimable task Michal Hocko
2018-08-07 10:15 ` Tetsuo Handa
2018-08-07 11:04   ` Michal Hocko
2018-08-07 20:19   ` Johannes Weiner
2018-08-07 20:38     ` Tetsuo Handa
2018-08-08 12:57       ` Tetsuo Handa
2018-08-08 13:16         ` Michal Hocko [this message]
2018-08-07 20:02 ` Johannes Weiner
2018-08-07 20:23   ` Michal Hocko
2018-08-07 20:54     ` Johannes Weiner
2018-08-08  6:44       ` Michal Hocko
2018-08-08  7:12         ` Michal Hocko
2018-08-08  7:13           ` [PATCH 1/2] " Michal Hocko
2018-08-08  7:13           ` [PATCH 2/2] memcg, oom: emit oom report when there is no eligible task Michal Hocko
2018-08-08 14:45             ` Johannes Weiner
2018-08-08 16:17               ` Michal Hocko
2018-08-21 14:06                 ` Michal Hocko
2018-08-21 17:20                   ` Johannes Weiner

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