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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>,
	linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, guro@fb.com,
	kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
	rientjes@google.com, yang.s@alibaba-inc.com,
	Andrew Morton <akpm@linux-foundation.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RFC PATCH] memcg, oom: throttle dump_header for memcg ooms without eligible tasks
Date: Fri, 12 Oct 2018 21:58:19 +0900	[thread overview]
Message-ID: <0417c888-d74e-b6ae-a8f0-234cbde03d38@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20181012124137.GA29330@cmpxchg.org>

Calling printk() people. ;-)

On 2018/10/12 21:41, Johannes Weiner wrote:
> On Fri, Oct 12, 2018 at 09:10:40PM +0900, Tetsuo Handa wrote:
>> On 2018/10/12 21:08, Michal Hocko wrote:
>>>> So not more than 10 dumps in each 5s interval. That looks reasonable
>>>> to me. By the time it starts dropping data you have more than enough
>>>> information to go on already.
>>>
>>> Yeah. Unless we have a storm coming from many different cgroups in
>>> parallel. But even then we have the allocation context for each OOM so
>>> we are not losing everything. Should we ever tune this, it can be done
>>> later with some explicit examples.
>>>
>>>> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
>>>
>>> Thanks! I will post the patch to Andrew early next week.
>>>
>>
>> How do you handle environments where one dump takes e.g. 3 seconds?
>> Counting delay between first message in previous dump and first message
>> in next dump is not safe. Unless we count delay between last message
>> in previous dump and first message in next dump, we cannot guarantee
>> that the system won't lockup due to printk() flooding.
> 
> How is that different from any other printk ratelimiting? If a dump
> takes 3 seconds you need to fix your console. It doesn't make sense to
> design KERN_INFO messages for the slowest serial consoles out there.

You can't fix the console. It is a hardware limitation.

> 
> That's what we did, btw. We used to patch out the OOM header because
> our serial console was so bad, but obviously that's not a generic
> upstream solution. We've since changed the loglevel on the serial and
> use netconsole[1] for the chattier loglevels.
> 
> [1] https://github.com/facebook/fbkutils/tree/master/netconsd
> 

  reply	other threads:[~2018-10-12 12:58 UTC|newest]

Thread overview: 42+ 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
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
2018-10-10 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 [this message]
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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