From: Ted Ts'o <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: Tao Ma <tm@tao.ma>, linux-ext4@vger.kernel.org
Subject: Re: [PATCH] jbd2: Fix forever sleeping process in do_get_write_access()
Date: Sun, 8 May 2011 19:14:49 -0400 [thread overview]
Message-ID: <20110508231449.GF15585@thunk.org> (raw)
In-Reply-To: <1304597439-7185-1-git-send-email-jack@suse.cz>
On Thu, May 05, 2011 at 02:10:39PM +0200, Jan Kara wrote:
> In do_get_write_access() we wait on BH_Unshadow bit for buffer to get
> from shadow state. The waking code in journal_commit_transaction() has
> a bug because it does not issue a memory barrier after the buffer is moved
> from the shadow state and before wake_up_bit() is called. Thus a waitqueue
> check can happen before the buffer is actually moved from the shadow state
> and waiting process may never be woken. Fix the problem by issuing proper
> barrier.
>
> Reported-by: Tao Ma <boyu.mt@taobao.com>
> Signed-off-by: Jan Kara <jack@suse.cz>
Thanks, I've added this to the ext4 tree. (Currently in the dev
branch, pending testing.)
- Ted
prev parent reply other threads:[~2011-05-08 23:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-05 12:10 [PATCH] jbd2: Fix forever sleeping process in do_get_write_access() Jan Kara
2011-05-05 13:49 ` Eric Sandeen
2011-05-05 14:11 ` Jan Kara
2011-05-05 14:28 ` Eric Sandeen
2011-05-08 23:14 ` Ted Ts'o [this message]
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