Date: Tue, 5 Aug 2008 17:39:37 +1000
From: Dave Chinner <david@fromorbit.com>
To: Lachlan McIlroy <lachlan@sgi.com>
Cc: xfs-oss <xfs@oss.sgi.com>, xfs-dev <xfs-dev@sgi.com>
Subject: Re: [PATCH] Use KM_NOFS for debug trace buffers
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On Tue, Aug 05, 2008 at 05:09:59PM +1000, Lachlan McIlroy wrote:
> Use KM_NOFS to prevent recursion back into the filesystem which can
> cause deadlocks.
>
> In the case of xfs_iread() we hold the lock on the inode cluster buffer
> while allocating memory for the trace buffers.  If we recurse back into
> XFS to flush data that may require a transaction to allocate extents
> which needs log space.  This can deadlock with the xfsaild thread which
> can't push the tail of the log because it is trying to get the inode
> cluster buffer lock.

Looks OK.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com