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From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	syzbot <syzbot+77e6b28a7a7106ad0def@syzkaller.appspotmail.com>,
	hannes@cmpxchg.org, akpm@linux-foundation.org, guro@fb.com,
	kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, rientjes@google.com,
	syzkaller-bugs@googlegroups.com, yang.s@alibaba-inc.com,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Petr Mladek <pmladek@suse.com>
Subject: Re: INFO: rcu detected stall in shmem_fault
Date: Wed, 10 Oct 2018 20:48:33 +0900	[thread overview]
Message-ID: <20181010114833.GB3949@tigerII.localdomain> (raw)
In-Reply-To: <20181010113500.GH5873@dhcp22.suse.cz>

On (10/10/18 13:35), Michal Hocko wrote:
> > Just flooding out of memory messages can trigger RCU stall problems.
> > For example, a severe skbuff_head_cache or kmalloc-512 leak bug is causing
> 
> [...]
> 
> Quite some of them, indeed! I guess we want to rate limit the output.
> What about the following?

A bit unrelated, but while we are at it:

  I like it when we rate-limit printk-s that lookup the system.
But it seems that default rate-limit values are not always good enough,
DEFAULT_RATELIMIT_INTERVAL / DEFAULT_RATELIMIT_BURST can still be too
verbose. For instance, when we have a very slow IPMI emulated serial
console -- e.g. baud rate at 57600. DEFAULT_RATELIMIT_INTERVAL and
DEFAULT_RATELIMIT_BURST can add new OOM headers and backtraces faster
than we evict them.

Does it sound reasonable enough to use larger than default rate-limits
for printk-s in OOM print-outs? OOM reports tend to be somewhat large
and the reported numbers are not always *very* unique.

What do you think?

	-ss

  reply	other threads:[~2018-10-10 11:48 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-10  0:08 syzbot
2018-10-10  0:12 ` Tetsuo Handa
2018-10-10  4:11   ` David Rientjes
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 [this message]
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
2018-10-10 15:11   ` Michal Hocko
2018-10-11  6:37   ` Tetsuo Handa
2018-10-11  6:37     ` Tetsuo Handa
2018-10-12 10:47     ` 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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