linux-ext4 - Re: [PATCH] jbd2: Fix forever sleeping process in do_get_write

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Date:	Thu, 05 May 2011 09:28:30 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Jan Kara <jack@...e.cz>
CC:	tytso@....edu, Tao Ma <tm@....ma>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] jbd2: Fix forever sleeping process in do_get_write_access()

On 5/5/11 9:11 AM, Jan Kara wrote:
> On Thu 05-05-11 08:49:14, Eric Sandeen wrote:
>> On 5/5/11 7:10 AM, 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.
>>
>> needed for jbd/commit.c as well, I guess?
>   Yes, I was already queued in my tree. I just sent it to the list as well.

sorry, sometimes "we" forget :)

Thanks!
-Eric
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