From: Dave Chinner <david@fromorbit.com>
To: Tao Ma <tm@tao.ma>
Cc: Theodore Ts'o <tytso@mit.edu>,
Jiaying Zhang <jiayingz@google.com>,
linux-ext4@vger.kernel.org
Subject: Re: [URGENT PATCH] ext4: fix potential deadlock in ext4_evict_inode()
Date: Fri, 26 Aug 2011 19:24:26 +1000 [thread overview]
Message-ID: <20110826092426.GB3162@dastard> (raw)
In-Reply-To: <4E576152.9060405@tao.ma>
On Fri, Aug 26, 2011 at 05:03:14PM +0800, Tao Ma wrote:
> On 08/26/2011 04:44 PM, Dave Chinner wrote:
> > On Fri, Aug 26, 2011 at 05:35:07PM +1000, Dave Chinner wrote:
> >> On Thu, Aug 25, 2011 at 11:33:44PM -0400, Theodore Ts'o wrote:
> >>>
> >>> Note: this will probably need to be sent to Linus as an emergency
> >>> bugfix ASAP, since it was introduced in 3.1-rc1, so it represents a
> >>> regression.
> >>
> >> It doesn't appear to be a bug. All of the new ext4 lockdep reports
> >> in 3.1 I've seen (except for the mmap_sem/i_mutex one) are false
> >> positives....
> >
> > While the lockdep report is false positive, I agree that your
> > change is the right fix to make - the IO completions are already
> > queued on the workqueue, so they don't need to be flushed to get
> > them to complete. All that needs to be done is call
> > ext4_ioend_wait() for them to complete, and that gets rid of the
> > i_mutex altogether. (*)
> ext4_ioend_wait can't work here for a nasty bug. Please see the commit
> log of 2581fdc8.
Unless I'm missing something, the described race with
ext4_truncate() flushing completions without the i_mutex lock held
cannot occur if you've already waited for all pending completions to
drain by calling ext4_ioend_wait()....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2011-08-26 9:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-26 3:33 [URGENT PATCH] ext4: fix potential deadlock in ext4_evict_inode() Theodore Ts'o
2011-08-26 3:56 ` Tao Ma
2011-08-26 9:28 ` Tao Ma
2011-08-26 7:35 ` Dave Chinner
2011-08-26 7:42 ` Tao Ma
2011-08-26 8:44 ` Dave Chinner
2011-08-26 8:50 ` Christoph Hellwig
2011-08-26 9:10 ` Tao Ma
2011-08-26 9:17 ` Christoph Hellwig
2011-08-26 11:35 ` Theodore Tso
2011-08-26 14:53 ` Tao Ma
2011-08-26 9:03 ` Tao Ma
2011-08-26 9:24 ` Dave Chinner [this message]
2011-08-26 9:27 ` Tao Ma
2011-08-26 15:52 ` Ted Ts'o
2011-08-26 16:58 ` Jiaying Zhang
2011-08-26 20:22 ` Ted Ts'o
2011-08-27 5:17 ` Jiaying Zhang
2011-08-31 1:15 ` Jiaying Zhang
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=20110826092426.GB3162@dastard \
--to=david@fromorbit.com \
--cc=jiayingz@google.com \
--cc=linux-ext4@vger.kernel.org \
--cc=tm@tao.ma \
--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