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References: <0252ad5d-46e6-0d7f-ef91-4e316657a83d@i-love.sakura.ne.jp>
 <CACT4Y+Yp6ZbusCWg5C1zaJpcS8=XnGPboKgWfyxVk1axQA2nbw@mail.gmail.com> <201809060553.w865rmpj036017@www262.sakura.ne.jp>
From: Dmitry Vyukov <dvyukov@google.com>
Date: Thu, 6 Sep 2018 11:54:02 +0200
Message-ID: <CACT4Y+YKJWJr-5rBQidt6nY7+VF=BAsvHyh+XTaf8spwNy3qPA@mail.gmail.com>
Subject: Re: INFO: task hung in ext4_da_get_block_prep
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Sender: owner-linux-mm@kvack.org
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To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: syzbot <syzbot+f0fc7f62e88b1de99af3@syzkaller.appspotmail.com>, 'Dmitry Vyukov' via syzkaller-upstream-moderation <syzkaller-upstream-moderation@googlegroups.com>, linux-mm <linux-mm@kvack.org>, Michal Hocko <mhocko@kernel.org>

On Thu, Sep 6, 2018 at 7:53 AM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
> Dmitry Vyukov wrote:
>> > Also, another notable thing is that the backtrace for some reason includes
>> >
>> > [ 1048.211540]  ? oom_killer_disable+0x3a0/0x3a0
>> >
>> > line. Was syzbot testing process freezing functionality?
>>
>> What's the API for this?
>>
>
> I'm not a user of suspend/hibernation. But it seems that usage of the API
> is to write one of words listed in /sys/power/state into /sys/power/state .
>
> # echo suspend > /sys/power/state

syzkaller should not write to /sys/power/state. The only mention of
"power" is in some selinux contexts.