Re: [PATCH] xfs: fix memory reclaim deadlock on agi buffer

[Dave Chinner <david@fromorbit.com>]

On Mon, May 07, 2012 at 04:11:37PM -0400, Peter Watkins wrote:
> Note xfs_iget can be called while holding a locked agi buffer. If
> it goes into memory reclaim then inode teardown may try to lock the
> same buffer. Prevent the deadlock by calling radix_tree_preload
> with GFP_NOFS.
> 
> Signed-off-by: Peter Watkins <treestem@gmail.com>

This might be one for the stable kernel as well. Ben, can you add a
"cc: stable@vger.kernel.org" to the commit message for this one?

> ---
>  fs/xfs/xfs_iget.c |    5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
> index bcc6c24..8c6f806 100644
> --- a/fs/xfs/xfs_iget.c
> +++ b/fs/xfs/xfs_iget.c
> @@ -334,9 +334,10 @@ xfs_iget_cache_miss(
>  	/*
>  	 * Preload the radix tree so we can insert safely under the
>  	 * write spinlock. Note that we cannot sleep inside the preload
> -	 * region.
> +	 * region. Since we can be called from transaction context, don't
> +	 * recurse into the file system.
>  	 */
> -	if (radix_tree_preload(GFP_KERNEL)) {
> +	if (radix_tree_preload(GFP_NOFS)) {
>  		error = EAGAIN;
>  		goto out_destroy;
>  	}

Looks good. Thanks for the quick turn-around, Peter.

Reviewed-by: Dave Chinner <dchinner@redhat.com>

-- 
Dave Chinner
david@fromorbit.com

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs