From: "Alex Lyakas" <alex@zadarastorage.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: xfs_vm_releasepage() causing BUG at free_buffer_head()
Date: Wed, 20 Jul 2016 12:42:54 +0300 [thread overview]
Message-ID: <08BA7450B9BF4B64A74B8DF97986CD35@alyakaslap> (raw)
In-Reply-To: <20160719231108.GH16044@dastard>
Hello Dave,
Grepping through my kernel source code, I see the following:
- direct users of b_assoc_buffers are nilfs2, reiserfs and jbd2. In my case,
jbd2 is used by ext4. Looking at jbd2 usage, however, it looks like it
handles this list correctly.
- the only other place where somebody can use the "b_assoc_buffers" link is
by calling mark_buffer_dirty_inode(), which puts the bufferhead on
"mapping->private_list" using the "b_assoc_buffers" link. There are several
users of this API, but for my case the only relevant being again jbd2.
Therefore, I will ask on the ext4 community.
Thanks,
Alex.
-----Original Message-----
From: Dave Chinner
Sent: Wednesday, July 20, 2016 2:11 AM
To: Alex Lyakas
Cc: xfs@oss.sgi.com
Subject: Re: xfs_vm_releasepage() causing BUG at free_buffer_head()
On Mon, Jul 18, 2016 at 09:00:41PM +0300, Alex Lyakas wrote:
> Greetings XFS community,
>
> We have hit the following BUG [1].
>
> This is in free_buffer_head():
> BUG_ON(!list_empty(&bh->b_assoc_buffers));
XFS doesn't use the bh->b_assoc_buffers field at all, so nothing in
XFS should ever corrupt it. Do you have any extN filesystems active,
or any other filesystems/block devices that use bufferheads than
might have a use after free bug? e.g. a long time ago (circa
~2.6.16, IIRC) we had a bufferhead corruption problem detected in
XFS that was actually caused by a reiserfs use after free.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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prev parent reply other threads:[~2016-07-20 9:43 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-18 18:00 xfs_vm_releasepage() causing BUG at free_buffer_head() Alex Lyakas
2016-07-18 20:18 ` Holger Hoffstätte
2016-07-19 8:43 ` Alex Lyakas
2016-07-19 11:24 ` Holger Hoffstätte
2016-07-19 23:05 ` Dave Chinner
2016-07-19 23:11 ` Dave Chinner
2016-07-20 9:42 ` Alex Lyakas [this message]
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