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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Michal Hocko <mhocko@suse.com>
Cc: linux-mm@kvack.org, Roman Gushchin <guro@fb.com>,
	Shakeel Butt <shakeelb@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] mm, oom: avoid printk() iteration under RCU
Date: Thu, 18 Jul 2019 22:50:14 +0900	[thread overview]
Message-ID: <7478e014-e5ce-504c-34b6-f2f9da952600@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20190718083014.GB30461@dhcp22.suse.cz>

On 2019/07/18 17:30, Michal Hocko wrote:
> On Wed 17-07-19 19:55:01, Tetsuo Handa wrote:
>> Currently dump_tasks() might call printk() for many thousands times under
>> RCU, which might take many minutes for slow consoles.
> 
> Is is even wise to enable dumping tasks on systems with thousands of
> tasks and slow consoles? I mean you still have to call printk that is
> slow that many times. So why do we actually care? Because of RCU stall
> warnings?
> 

That's a stupid question. WE DO CARE.
We are making efforts for avoid calling printk() on each thread group (e.g.

  commit 0c1b2d783cf34324 ("mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process()")
  commit b2b469939e934587 ("proc, oom: do not report alien mms when setting oom_score_adj"))

) under RCU and this patch is one of them (except that we can't remove
printk() for dump_tasks() case).


  reply	other threads:[~2019-07-18 14:47 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-17 10:55 [PATCH] mm, oom: avoid printk() iteration under RCU Tetsuo Handa
2019-07-18  0:31 ` Shakeel Butt
2019-07-18 10:22   ` Tetsuo Handa
2019-07-18  8:30 ` Michal Hocko
2019-07-18 13:50   ` Tetsuo Handa [this message]
2019-07-18 14:02     ` Michal Hocko
2019-07-20 11:29       ` Tetsuo Handa
     [not found]         ` <20190920171042.8d970f9fc6f360de9b20ebbe@linux-foundation.org>
2019-09-21 20:30           ` Michal Hocko
     [not found]             ` <11c42f07-74d1-d4be-99bc-ca50d7c0ec71@i-love.sakura.ne.jp>
2019-09-22  6:20               ` Michal Hocko
     [not found]                 ` <e4fac741-7dbc-41a1-7b9e-249415fba612@i-love.sakura.ne.jp>
2019-09-23  8:23                   ` Michal Hocko
2019-07-23 23:14 ` Andrew Morton
2019-07-24  1:47   ` Tetsuo Handa

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