From: Shakeel Butt <shakeelb@google.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
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: Sat, 15 Jun 2019 11:50:31 -0700 [thread overview]
Message-ID: <CALvZod4etSv9Hv4UD=E6D7U4vyjCqhxQgq61AoTUCd+VubofFg@mail.gmail.com> (raw)
In-Reply-To: <5bb1fe5d-f0e1-678b-4f64-82c8d5d81f61@i-love.sakura.ne.jp>
On Sat, Jun 15, 2019 at 9:49 AM Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> On 2019/06/16 1:11, Shakeel Butt wrote:
> > On Sat, Jun 15, 2019 at 6:50 AM Michal Hocko <mhocko@kernel.org> wrote:
> >> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> >> index 5a58778c91d4..43eb479a5dc7 100644
> >> --- a/mm/oom_kill.c
> >> +++ b/mm/oom_kill.c
> >> @@ -161,8 +161,8 @@ static bool oom_unkillable_task(struct task_struct *p,
> >> return true;
> >>
> >> /* When mem_cgroup_out_of_memory() and p is not member of the group */
> >> - if (memcg && !task_in_mem_cgroup(p, memcg))
> >> - return true;
> >> + if (memcg)
> >> + return false;
> >
> > This will break the dump_tasks() usage of oom_unkillable_task(). We
> > can change dump_tasks() to traverse processes like
> > mem_cgroup_scan_tasks() for memcg OOMs.
>
> 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).
> To avoid printk()ing all threads in a thread group,
> moving that check to
>
> if (memcg && !task_in_mem_cgroup(p, memcg))
> continue;
>
> in dump_tasks() is better?
>
> >
> >>
> >> /* p may not have freeable memory in nodemask */
> >> if (!has_intersects_mems_allowed(p, nodemask))
>
next prev parent reply other threads:[~2019-06-15 18:50 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 [this message]
2019-06-15 21:33 ` Tetsuo Handa
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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