All of lore.kernel.org
 help / color / mirror / Atom feed
From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@kernel.org>
Cc: 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: Sat, 13 Oct 2018 20:09:30 +0900	[thread overview]
Message-ID: <bb2074c0-34fe-8c2c-1c7d-db71338f1e7f@i-love.sakura.ne.jp> (raw)
In-Reply-To: <0417c888-d74e-b6ae-a8f0-234cbde03d38@i-love.sakura.ne.jp>

On 2018/10/12 21:58, Tetsuo Handa wrote:
> 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.

Not reasonable at all.

>>>>
>>>> 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.
>>>>

One thread from one cgroup is sufficient. I don't think that Michal's patch
is an appropriate mitigation. It still needlessly floods kernel log buffer
and significantly defers recovery operation.

Nacked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

---------- Testcase ----------

#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
	FILE *fp;
	const unsigned long size = 1048576 * 200;
	char *buf = malloc(size);
	mkdir("/sys/fs/cgroup/memory/test1", 0755);
	fp = fopen("/sys/fs/cgroup/memory/test1/memory.limit_in_bytes", "w");
	fprintf(fp, "%lu\n", size / 2);
	fclose(fp);
	fp = fopen("/sys/fs/cgroup/memory/test1/tasks", "w");
	fprintf(fp, "%u\n", getpid());
	fclose(fp);
	fp = fopen("/proc/self/oom_score_adj", "w");
	fprintf(fp, "-1000\n");
	fclose(fp);
	fp = fopen("/dev/zero", "r");
	fread(buf, 1, size, fp);
	fclose(fp);
	return 0;
}

---------- Michal's patch ----------

73133 lines (5.79MB) of kernel messages per one run

[root@ccsecurity ~]# time ./a.out

real    3m44.389s
user    0m0.000s
sys     3m42.334s

[root@ccsecurity ~]# time ./a.out

real    3m41.767s
user    0m0.004s
sys     3m39.779s

---------- My v2 patch ----------

50 lines (3.40 KB) of kernel messages per one run

[root@ccsecurity ~]# time ./a.out

real    0m5.227s
user    0m0.000s
sys     0m4.950s

[root@ccsecurity ~]# time ./a.out

real    0m5.249s
user    0m0.000s
sys     0m4.956s


  reply	other threads:[~2018-10-13 11:09 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
2018-10-13 11:09             ` Tetsuo Handa [this message]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=bb2074c0-34fe-8c2c-1c7d-db71338f1e7f@i-love.sakura.ne.jp \
    --to=penguin-kernel@i-love.sakura.ne.jp \
    --cc=akpm@linux-foundation.org \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=kirill.shutemov@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=pmladek@suse.com \
    --cc=rientjes@google.com \
    --cc=rostedt@goodmis.org \
    --cc=sergey.senozhatsky.work@gmail.com \
    --cc=sergey.senozhatsky@gmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=yang.s@alibaba-inc.com \
    --subject='Re: [RFC PATCH] memcg, oom: throttle dump_header for memcg ooms without eligible tasks' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.