From: ChunYu Wang <chunwang@redhat.com>
To: Andreas Dilger <adilger@dilger.ca>
Cc: GeneBlue <geneblue.mail@gmail.com>,
"Theodore Ts'o" <tytso@mit.edu>,
linux-ext4 <linux-ext4@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: kernel BUG at fs/ext4/fsync.c:LINE!
Date: Fri, 15 Sep 2017 02:22:01 +0800 [thread overview]
Message-ID: <CAOm2TWzK0VugZo5ZpWLj5c+f3M0mKPxecjs1oA1g86v1e3kGFA@mail.gmail.com> (raw)
In-Reply-To: <CE0032C8-A8FE-42C2-BFD8-06411B393FF3@dilger.ca>
On Fri, Sep 15, 2017 at 12:41 AM, Andreas Dilger <adilger@dilger.ca> wrote:
> I don't think a reproducer is needed. It looks like the fsync callpath
> is happening from an IRQ context due to IO completion, and then re-entering
> the filesystem while a transaction is already started. It looks like the
> original IO was submitted with AIO based on the functions on the IRQ stack,
> which is likely why nobody has hit it (AIO isn't very commonly used).
>
> That said, I don't follow the reasoning behind the convoluted series of AIO
> callbacks that has IO _completion_ calling vfs_fsync_range() and re-entering
> the filesystem to flush out more data?
Thanks for analyzing, and I do think the syzkaller reproducer(in fact,
log) may also answer your question and help positioning the precise
issue trigger in-depth. Moreover, for me, I am not professional enough
to analyze such a complex problem with call trace and code only :)
- ChunYu
prev parent reply other threads:[~2017-09-14 18:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CACbyUSr1AEJ3E+wB7a1ftuxH4sSK=i5v1Z+KUJ0TMygUrtdPRQ@mail.gmail.com>
2017-09-14 15:04 ` kernel BUG at fs/ext4/fsync.c:LINE! ChunYu Wang
2017-09-14 16:41 ` Andreas Dilger
2017-09-14 18:22 ` ChunYu Wang [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAOm2TWzK0VugZo5ZpWLj5c+f3M0mKPxecjs1oA1g86v1e3kGFA@mail.gmail.com \
--to=chunwang@redhat.com \
--cc=adilger@dilger.ca \
--cc=geneblue.mail@gmail.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=syzkaller@googlegroups.com \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).