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[209.85.220.65]) by mx.google.com with SMTPS id o5sor3791780ywe.207.2019.06.15.11.50.43 for (Google Transport Security); Sat, 15 Jun 2019 11:50:43 -0700 (PDT) Received-SPF: pass (google.com: domain of shakeelb@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=DAZVeS1q; spf=pass (google.com: domain of shakeelb@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=shakeelb@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=hsw6F/JD0JWJFl9lCNc3fmoZkyiWfJZZGwD/Q8JM96E=; b=DAZVeS1q+rG3Nj2CWnwq7DHcMWuAHnWUfvQj4jBHVPsTl5nhWKrgVhJUUzuaF0ESvk 9eZvFxBsHqnD/OxOhv8KPKD7qenAUU9QH6cyxZ8OswyYoUAg0VAY/YeSsBUHNUyHuJR5 cTtHZLZJeL3xDglL9EloZvp6FX+pnNYiVLAmZRhrm1DLObhvU9lqguPMwTtsaC+IJAQd bh8Z4kq7Sn3K9OphUToOxMdmVxkx+d1IYhPE/ifulxO3wRLtFK3aPQIEx7qhXPgBFKVx gBmTgFFfTemmMa9Zgtk+McMQFRqyf86pW/q2zkP6H4vhzPb472GPRtkEjLLVoAusqZBJ 3KQw== X-Google-Smtp-Source: APXvYqxF93Zv7RM/vG5muLgCFR7l8abVBfZg9loqw5+gonEsrR4vX5i/9gEWNuseLjVXSacAq3q/fuV7TpoQYxUOrH0= X-Received: by 2002:a81:3a0f:: with SMTP id h15mr56987138ywa.34.1560624643001; Sat, 15 Jun 2019 11:50:43 -0700 (PDT) MIME-Version: 1.0 References: <0000000000004143a5058b526503@google.com> <20190615134955.GA28441@dhcp22.suse.cz> <5bb1fe5d-f0e1-678b-4f64-82c8d5d81f61@i-love.sakura.ne.jp> In-Reply-To: <5bb1fe5d-f0e1-678b-4f64-82c8d5d81f61@i-love.sakura.ne.jp> From: Shakeel Butt Date: Sat, 15 Jun 2019 11:50:31 -0700 Message-ID: Subject: Re: general protection fault in oom_unkillable_task To: Tetsuo Handa Cc: Michal Hocko , syzbot , Andrew Morton , "Eric W. Biederman" , Roman Gushchin , Johannes Weiner , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , LKML , Linux MM , syzkaller-bugs , yuzhoujian@didichuxing.com Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Jun 15, 2019 at 9:49 AM Tetsuo Handa wrote: > > On 2019/06/16 1:11, Shakeel Butt wrote: > > On Sat, Jun 15, 2019 at 6:50 AM Michal Hocko 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)) >