From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Shakeel Butt <shakeelb@google.com>
Cc: "Michal Hocko" <mhocko@kernel.org>,
syzbot <syzbot+d0fc9d3c166bc5e4a94b@syzkaller.appspotmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Roman Gushchin" <guro@fb.com>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Jérôme Glisse" <jglisse@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"Linux MM" <linux-mm@kvack.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
yuzhoujian@didichuxing.com
Subject: Re: general protection fault in oom_unkillable_task
Date: Sun, 16 Jun 2019 06:33:51 +0900 [thread overview]
Message-ID: <791594c6-45a3-d78a-70b5-901aa580ed9f@i-love.sakura.ne.jp> (raw)
In-Reply-To: <CALvZod4etSv9Hv4UD=E6D7U4vyjCqhxQgq61AoTUCd+VubofFg@mail.gmail.com>
On 2019/06/16 3:50, Shakeel Butt wrote:
>> While dump_tasks() traverses only each thread group, mem_cgroup_scan_tasks()
>> traverses each thread.
>
> I think mem_cgroup_scan_tasks() traversing threads is not intentional
> and css_task_iter_start in it should use CSS_TASK_ITER_PROCS as the
> oom killer only cares about the processes or more specifically
> mm_struct (though two different thread groups can have same mm_struct
> but that is fine).
We can't use CSS_TASK_ITER_PROCS from mem_cgroup_scan_tasks(). I've tried
CSS_TASK_ITER_PROCS in an attempt to evaluate only one thread from each
thread group, but I found that CSS_TASK_ITER_PROCS causes skipping whole
threads in a thread group (and trivially allowing "Out of memory and no
killable processes...\n" flood) if thread group leader has already exited.
If we can agree with using a flag in mm_struct in order to track whether
each mm_struct was already evaluated for each out_of_memory() call, we can
printk() only one thread from all thread groups sharing that mm_struct...
next prev parent reply other threads:[~2019-06-15 21:34 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-15 1:08 general protection fault in oom_unkillable_task syzbot
2019-06-15 1:10 ` Tetsuo Handa
2019-06-15 15:59 ` Tetsuo Handa
2019-06-15 3:15 ` Shakeel Butt
2019-06-15 13:49 ` Michal Hocko
2019-06-15 16:11 ` Shakeel Butt
2019-06-15 16:48 ` Tetsuo Handa
2019-06-15 18:50 ` Shakeel Butt
2019-06-15 21:33 ` Tetsuo Handa [this message]
2019-06-16 7:37 ` Tetsuo Handa
2019-06-16 15:13 ` Tetsuo Handa
2019-06-17 6:31 ` Michal Hocko
2019-06-17 13:23 ` Shakeel Butt
2019-06-18 1:45 ` Andrew Morton
2019-06-18 4:21 ` Shakeel Butt
2019-06-17 6:33 ` Michal Hocko
2019-06-17 9:56 ` Tetsuo Handa
2019-06-17 10:13 ` Michal Hocko
2019-06-16 5:48 ` Hillf Danton
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