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From: Shaohua Li <shli@kernel.org>
To: Dave Chinner <david@fromorbit.com>
Cc: hch@infradead.org, xfs@oss.sgi.com
Subject: Re: [RFC]xfs: using GFP_NOFS for blkdev_issue_flush
Date: Tue, 24 Apr 2012 21:23:46 +0800	[thread overview]
Message-ID: <20120424132346.GA24575@kernel.org> (raw)
In-Reply-To: <20120418013746.GL6734@dastard>

On Wed, Apr 18, 2012 at 11:37:46AM +1000, Dave Chinner wrote:
> On Mon, Apr 16, 2012 at 02:58:21PM +0800, Shaohua Li wrote:
> > On 4/16/12 2:49 PM, Shaohua Li wrote:
> > >
> > >flush request is issued in transaction commit code path usually, so
> > >looks using
> > >GFP_KERNEL to allocate memory for flush request bio falls into the classic
> > >deadlock issue (memory reclaim recursion). Use GFP_NOFS to avoid recursion
> > >from reclaim context. Per Dave Chinner, there is only blkdev_issue_flush
> > >might
> > >be buggy here. But using GFP_NOFS by default for all calls should not
> > >matter.
> 
> Can you update the commit message like I suggested previously?
Copied exactly.


Issuing a block device flush request in transaction context using GFP_KERNEL
directly can cause deadlocks due to memory reclaim recursion. Use GFP_NOFS to
avoid recursion from reclaim context.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
---
 fs/xfs/xfs_super.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux/fs/xfs/xfs_super.c
===================================================================
--- linux.orig/fs/xfs/xfs_super.c	2012-04-13 10:08:26.095496072 +0800
+++ linux/fs/xfs/xfs_super.c	2012-04-13 10:08:42.555496865 +0800
@@ -622,7 +622,7 @@ void
 xfs_blkdev_issue_flush(
 	xfs_buftarg_t		*buftarg)
 {
-	blkdev_issue_flush(buftarg->bt_bdev, GFP_KERNEL, NULL);
+	blkdev_issue_flush(buftarg->bt_bdev, GFP_NOFS, NULL);
 }
 
 STATIC void

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  reply	other threads:[~2012-04-24 13:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-16  6:49 [RFC]xfs: using GFP_NOFS for blkdev_issue_flush Shaohua Li
2012-04-16  6:58 ` Shaohua Li
2012-04-17 18:42   ` Mark Tinguely
2012-04-18  1:37   ` Dave Chinner
2012-04-24 13:23     ` Shaohua Li [this message]
2012-04-25  0:25       ` Dave Chinner

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