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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	syzbot <syzbot+9933e4476f365f5d5a1b@syzkaller.appspotmail.com>,
	linux-mm@kvack.org, mgorman@techsingularity.net,
	Michal Hocko <mhocko@kernel.org>,
	ak@linux.intel.com, jack@suse.cz, jlayton@redhat.com,
	linux-kernel@vger.kernel.org, mawilcox@microsoft.com,
	syzkaller-bugs@googlegroups.com, tim.c.chen@linux.intel.com,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: INFO: task hung in generic_file_write_iter
Date: Tue, 31 Jul 2018 00:07:22 +0900	[thread overview]
Message-ID: <a2df1f24-f649-f5d8-0b2d-66d45b6cb61f@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20180720130602.f3d6dc4c943558875a36cb52@linux-foundation.org>

On 2018/07/21 5:06, Andrew Morton wrote:
> On Fri, 20 Jul 2018 19:36:23 +0900 Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
> 
>>>
>>> This report is stalling after mount() completed and process used remap_file_pages().
>>> I think that we might need to use debug printk(). But I don't know what to examine.
>>>
>>
>> Andrew, can you pick up this debug printk() patch?
>> I guess we can get the result within one week.
> 
> Sure, let's toss it in -next for a while.
> 
>> >From 8f55e00b21fefffbc6abd9085ac503c52a302464 Mon Sep 17 00:00:00 2001
>> From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
>> Date: Fri, 20 Jul 2018 19:29:06 +0900
>> Subject: [PATCH] fs/buffer.c: add debug print for __getblk_gfp() stall problem
>>
>> Among syzbot's unresolved hung task reports, 18 out of 65 reports contain
>> __getblk_gfp() line in the backtrace. Since there is a comment block that
>> says that __getblk_gfp() will lock up the machine if try_to_free_buffers()
>> attempt from grow_dev_page() is failing, let's start from checking whether
>> syzbot is hitting that case. This change will be removed after the bug is
>> fixed.
> 
> I'm not sure that grow_dev_page() is hanging.  It has often been
> suspected, but always is proven innocent.  Lets see.

syzbot reproduced this problem ( https://syzkaller.appspot.com/text?tag=CrashLog&x=11f2fc44400000 ) .
It says that grow_dev_page() is returning 1 but __find_get_block() is failing forever. Any idea?


  reply	other threads:[~2018-07-30 15:08 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-18  8:58 INFO: task hung in generic_file_write_iter syzbot
2018-07-18 10:28 ` Tetsuo Handa
2018-07-18 10:36   ` Dmitry Vyukov
2018-07-20 10:36   ` Tetsuo Handa
2018-07-20 10:36     ` Tetsuo Handa
2018-07-20 10:36     ` Tetsuo Handa
2018-07-20 20:06     ` Andrew Morton
2018-07-30 15:07       ` Tetsuo Handa [this message]
2018-08-06 10:09         ` Jan Kara
2018-08-06 11:56           ` Tetsuo Handa
2018-08-20 14:12             ` Tetsuo Handa
2018-12-28 13:34           ` Tetsuo Handa
2019-01-02 14:40             ` Jan Kara
2019-01-02 14:46               ` Dmitry Vyukov
2019-01-02 14:46                 ` Dmitry Vyukov
2019-01-02 16:07               ` Tetsuo Handa
2019-01-02 16:07                 ` Tetsuo Handa
2019-01-02 17:26                 ` Jan Kara
2019-01-03  0:46                   ` Tetsuo Handa
2019-01-03  0:46                     ` Tetsuo Handa
2019-01-08 10:04                   ` Tetsuo Handa
2019-01-08 11:24                     ` Jan Kara
2019-01-08 11:49                       ` Dmitry Vyukov
2019-01-08 11:49                         ` Dmitry Vyukov
2019-01-09 13:30                         ` Jan Kara
2019-01-14 15:11                           ` Dmitry Vyukov
2019-01-14 15:11                             ` Dmitry Vyukov
2019-01-14 15:13                             ` Dmitry Vyukov
2019-01-14 15:13                               ` Dmitry Vyukov
2019-01-15  9:29                               ` Jan Kara

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