From: Jan Kara <jack@suse.cz>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Vlastimil Babka <vbabka@suse.cz>,
syzbot <syzbot+fe601f9e887449d40112@syzkaller.appspotmail.com>,
linux-mm@kvack.org, syzkaller-bugs@googlegroups.com,
Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org
Subject: Re: WARNING in unaccount_page_cache_page
Date: Thu, 19 Dec 2019 10:45:42 +0100 [thread overview]
Message-ID: <20191219094542.GA24349@quack2.suse.cz> (raw)
In-Reply-To: <c7861417-c7f1-e4f1-336d-f2990ffd325e@I-love.SAKURA.ne.jp>
On Sat 30-11-19 00:30:03, Tetsuo Handa wrote:
> On 2019/11/29 23:41, Vlastimil Babka wrote:
> > On 11/29/19 9:19 AM, syzbot wrote:
> >> Hello,
> >>
> >> syzbot found the following crash on:
> >>
> >> HEAD commit: 089cf7f6 Linux 5.3-rc7
> >
> > Ugh, why test previous cycle's rc7 now? Typo for 5.4?
> >
> >> git tree: upstream
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=1210a761600000
> >> kernel config: https://syzkaller.appspot.com/x/.config?x=b89bb446a3faaba4
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=fe601f9e887449d40112
> >> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
>
> Please open the dashboard link. The first occurrence was 5.3-rc7 and the last
> occurrence was 5.4-rc7+. In other words, this bug is likely not yet fixed.
I've briefly looked at this so I'll dump my memory state here in case
someone wants to have a look (or for me when I get more time to look into
this):
The problem always happens on block device mapping. What I think is
happening is that truncate_inode_pages() races with some filesystem on top
of that block device holding buffer_head reference and calling
mark_buffer_dirty(). The buffer_head reference makes block_invalidatepage()
fail invalidating page buffers (try_to_release_page() respectively) and
following mark_buffer_dirty() call will happily redirty the page in
whatever state it is.
Now I didn't yet made up my mind what would be a proper way to fix this...
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
prev parent reply other threads:[~2019-12-19 9:45 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-29 8:19 WARNING in unaccount_page_cache_page syzbot
2019-11-29 14:41 ` Vlastimil Babka
[not found] ` <c7861417-c7f1-e4f1-336d-f2990ffd325e@I-love.SAKURA.ne.jp>
2019-12-19 9:45 ` Jan Kara [this message]
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