linux-kernel - Re: xfs_io "BUG: lock held when returning to user space!" on suspend

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Message-ID: <20080402215720.GI103491721@sgi.com>
Date:	Thu, 3 Apr 2008 07:57:20 +1000
From:	David Chinner <dgc@....com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	David Chinner <dgc@....com>, xfs-masters@....sgi.com,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: xfs_io "BUG: lock held when returning to user space!" on suspend

On Wed, Apr 02, 2008 at 11:58:54AM -0700, Jeremy Fitzhardinge wrote:
> I'm getting this:
> 
> ================================================
> [ BUG: lock held when returning to user space! ]
> ------------------------------------------------
> xfs_io/18796 is leaving the kernel with locks still held!
> 1 lock held by xfs_io/18796:
> #0:  (&type->s_umount_key#19){----}, at: [<c048c9ac>] get_super+0x42/0x87
> 
> when I suspend, possibly during an xfs-freeze.  There don't seem to be any 
> ill-effects.

Yup, both the sb->s_umount and bdev->bd_mount_sem seaphores are held
across freeze_bdev()/thaw_bdev(), and they are issued via separate
ioctls generally from separate processes. Not great design, but not
a bug....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group
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