linux-ext4 - Re: [PATCH 2/2] ext4: remove mb_groups before tearing buddy

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Message-ID: <20120601040933.GE7897@thunk.org>
Date:	Fri, 1 Jun 2012 00:09:33 -0400
From:	Ted Ts'o <tytso@....edu>
To:	Salman Qazi <sqazi@...gle.com>
Cc:	Ted Ts'o <tytso@...gle.com>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] ext4: remove mb_groups before tearing buddy_cache

On Tue, May 29, 2012 at 04:36:14PM -0700, Salman Qazi wrote:
> We can't have references held on pages in the s_buddy_cache while we are
> trying to truncate its pages and put the inode.  All the pages must be
> gone before we reach clear_inode.  This can only be gauranteed if we
> can prevent new users from grabbing references to s_buddy_cache's pages.
> 
> The original bug can be reproduced and the bug fix can be verified by:
> 
> while true; do mount -t ext4 /dev/ram0 /export/hda3/ram0; \
> 	umount /export/hda3/ram0; done &
> 
> while true; do cat /proc/fs/ext4/ram0/mb_groups; done
> 
> Signed-off-by: Salman Qazi <sqazi@...gle.com>

Applied, thanks.

						- Ted
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