From: Theodore Ts'o <tytso@mit.edu>
To: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: Eric Sandeen <sandeen@redhat.com>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] ext4: fix potential deadlock in ext4_nonda_switch()
Date: Thu, 27 Sep 2012 14:09:49 -0400 [thread overview]
Message-ID: <20120927180949.GA6862@thunk.org> (raw)
In-Reply-To: <87ipaziduh.fsf@openvz.org>
On Thu, Sep 27, 2012 at 09:18:30PM +0400, Dmitry Monakhov wrote:
> Hmm... even this '!' patch is still not good. I've got that complain
> WARNING: at fs/fs-writeback.c:1316 writeback_inodes_sb_nr+0x1a3/0x200()
This WARN_ON checking to make sure the s_umount mutex is grabbed.
What kernel are you applying this patch against? Commit 14da92001:
"fs: Protect write paths by sb_start_write - sb_end_write" adds a call
to sb_start_write() in generic_file_aio_write() which means by the
time we call ext4_nonda_switch(), s_umount is grabbed, which probably
explains why I'm not seeing this --- 14da92001 was added to mainline
as of 3.6-rc1, and I'm guessing you're using an older kernel?
This is something we need to consider, though, since "ext4: fix
potential deadlock in ext4_nonda_switch()" is currently marked for
stable, but commit 14da92001 is not marked for stable. So if this
commit gets backported w/o 14da92001, stable kernel users will see
this warning.
- Ted
next prev parent reply other threads:[~2012-09-27 18:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-20 3:23 [PATCH] ext4: fix potential deadlock in ext4_nonda_switch() Theodore Ts'o
2012-09-21 22:12 ` Eric Sandeen
2012-09-21 23:59 ` Theodore Ts'o
2012-09-27 17:18 ` Dmitry Monakhov
2012-09-27 18:09 ` Theodore Ts'o [this message]
2012-09-27 18:16 ` Dmitry Monakhov
2012-09-27 20:14 ` Theodore Ts'o
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=20120927180949.GA6862@thunk.org \
--to=tytso@mit.edu \
--cc=dmonakhov@openvz.org \
--cc=linux-ext4@vger.kernel.org \
--cc=sandeen@redhat.com \
--cc=stable@vger.kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.