From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Michal Hocko <mhocko@kernel.org>
Cc: syzbot <syzbot+bab151e82a4e973fa325@syzkaller.appspotmail.com>,
cgroups@vger.kernel.org, dvyukov@google.com, hannes@cmpxchg.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
syzkaller-bugs@googlegroups.com, vdavydov.dev@gmail.com
Subject: Re: WARNING in try_charge
Date: Tue, 7 Aug 2018 05:46:04 +0900 [thread overview]
Message-ID: <3cf8f630-73b7-20d4-8ad1-bb1c657ee30d@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20180806203437.GK10003@dhcp22.suse.cz>
On 2018/08/07 5:34, Michal Hocko wrote:
> On Tue 07-08-18 05:26:23, Tetsuo Handa wrote:
>> On 2018/08/07 2:56, Michal Hocko wrote:
>>> So the oom victim indeed passed the above force path after the oom
>>> invocation. But later on hit the page fault path and that behaved
>>> differently and for some reason the force path hasn't triggered. I am
>>> wondering how could we hit the page fault path in the first place. The
>>> task is already killed! So what the hell is going on here.
>>>
>>> I must be missing something obvious here.
>>>
>> YOU ARE OBVIOUSLY MISSING MY MAIL!
>>
>> I already said this is "mm, oom: task_will_free_mem(current) should ignore MMF_OOM_SKIP for once."
>> problem which you are refusing at https://www.spinics.net/lists/linux-mm/msg133774.html .
>> And you again ignored my mail. Very sad...
>
> Your suggestion simply didn't make much sense. There is nothing like
> first check is different from the rest.
>
I don't think your patch is appropriate. It avoids hitting WARN(1) but does not avoid
unnecessary killing of OOM victims.
If you look at https://syzkaller.appspot.com/text?tag=CrashLog&x=15a1c770400000 , you will
notice that both 23766 and 23767 are killed due to task_will_free_mem(current) == false.
This is "unnecessary killing of additional processes".
[ 365.869417] syz-executor2 invoked oom-killer: gfp_mask=0x6000c0(GFP_KERNEL), order=0, oom_score_adj=0
[ 365.878899] CPU: 0 PID: 23767 Comm: syz-executor2 Not tainted 4.18.0-rc6-next-20180725+ #18
(...snipped...)
[ 366.487490] Tasks state (memory values in pages):
[ 366.492349] [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
[ 366.501237] [ 23766] 0 23766 17620 8221 126976 0 0 syz-executor3
[ 366.510367] [ 23767] 0 23767 17618 8218 126976 0 0 syz-executor2
[ 366.519409] Memory cgroup out of memory: Kill process 23766 (syz-executor3) score 8252000 or sacrifice child
[ 366.529422] Killed process 23766 (syz-executor3) total-vm:70480kB, anon-rss:116kB, file-rss:32768kB, shmem-rss:0kB
[ 366.540456] oom_reaper: reaped process 23766 (syz-executor3), now anon-rss:0kB, file-rss:32000kB, shmem-rss:0kB
[ 366.550949] syz-executor3 invoked oom-killer: gfp_mask=0x6000c0(GFP_KERNEL), order=0, oom_score_adj=0
[ 366.560374] CPU: 1 PID: 23766 Comm: syz-executor3 Not tainted 4.18.0-rc6-next-20180725+ #18
(...snipped...)
[ 367.138136] Tasks state (memory values in pages):
[ 367.142986] [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
[ 367.151889] [ 23766] 0 23766 17620 8002 126976 0 0 syz-executor3
[ 367.160946] [ 23767] 0 23767 17618 8218 126976 0 0 syz-executor2
[ 367.169994] Memory cgroup out of memory: Kill process 23767 (syz-executor2) score 8249000 or sacrifice child
[ 367.180119] Killed process 23767 (syz-executor2) total-vm:70472kB, anon-rss:104kB, file-rss:32768kB, shmem-rss:0kB
[ 367.192101] oom_reaper: reaped process 23767 (syz-executor2), now anon-rss:0kB, file-rss:32000kB, shmem-rss:0kB
[ 367.202986] ------------[ cut here ]------------
[ 367.207845] Memory cgroup charge failed because of no reclaimable memory! This looks like a misconfiguration or a kernel bug.
[ 367.207965] WARNING: CPU: 1 PID: 23767 at mm/memcontrol.c:1710 try_charge+0x734/0x1680
[ 367.227540] Kernel panic - not syncing: panic_on_warn set ...
next prev parent reply other threads:[~2018-08-06 20:46 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-04 13:33 WARNING in try_charge syzbot
2018-08-04 13:45 ` Tetsuo Handa
2018-08-05 11:33 ` Tetsuo Handa
2018-08-05 8:14 ` syzbot
2018-08-06 9:15 ` Michal Hocko
2018-08-06 9:30 ` Dmitry Vyukov
2018-08-06 9:48 ` Michal Hocko
2018-08-06 10:34 ` Dmitry Vyukov
2018-08-06 11:02 ` Michal Hocko
2018-08-06 11:57 ` Dmitry Vyukov
2018-08-06 14:21 ` Michal Hocko
2018-08-06 14:58 ` Dmitry Vyukov
2018-08-06 17:30 ` Michal Hocko
2018-08-06 17:53 ` Dmitry Vyukov
2018-08-06 15:07 ` Dmitry Vyukov
2018-08-06 15:31 ` Johannes Weiner
2018-08-06 10:39 ` Dmitry Vyukov
2018-08-06 10:47 ` Tetsuo Handa
2018-08-06 11:09 ` Michal Hocko
2018-08-06 11:27 ` syzbot
2018-08-06 11:32 ` Michal Hocko
2018-08-06 11:58 ` Dmitry Vyukov
2018-08-06 14:41 ` Tetsuo Handa
2018-08-06 14:58 ` Michal Hocko
2018-08-06 15:12 ` Tetsuo Handa
2018-08-06 14:54 ` David Howells
2018-08-06 15:04 ` Tetsuo Handa
2018-08-06 11:00 ` syzbot
2018-08-06 15:32 ` Tetsuo Handa
2018-08-06 15:42 ` syzbot
2018-08-06 16:02 ` Tetsuo Handa
2018-08-06 17:44 ` Michal Hocko
2018-08-06 17:49 ` Dmitry Vyukov
2018-08-06 17:56 ` Michal Hocko
2018-08-06 18:13 ` Michal Hocko
2018-08-06 18:23 ` syzbot
2018-08-06 18:55 ` Michal Hocko
2018-08-06 19:12 ` syzbot
2018-08-06 19:45 ` Michal Hocko
2018-08-06 19:46 ` Michal Hocko
2018-08-07 11:18 ` Dmitry Vyukov
2018-08-07 11:25 ` Michal Hocko
2018-08-06 18:39 ` Michal Hocko
2018-08-06 20:26 ` Tetsuo Handa
2018-08-06 20:34 ` Michal Hocko
2018-08-06 20:46 ` Tetsuo Handa [this message]
2018-08-06 20:55 ` Michal Hocko
2018-08-06 21:50 ` Tetsuo Handa
2018-08-07 10:19 ` Tetsuo Handa
2018-08-09 13:57 ` Tetsuo Handa
2018-08-09 15:07 ` Michal Hocko
2018-08-09 21:05 ` Tetsuo Handa
2018-08-09 15:34 ` Johannes Weiner
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