linux-kernel - [ 38/91] md: using GFP_NOIO to allocate bio for flush request

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Message-Id: <20120527002515.148499606@linuxfoundation.org>
Date:	Sun, 27 May 2012 09:25:44 +0900
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Shaohua Li <shli@...ionio.com>,
	NeilBrown <neilb@...e.de>
Subject: [ 38/91] md: using GFP_NOIO to allocate bio for flush request

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Shaohua Li <shli@...nel.org>

commit b5e1b8cee7ad58a15d2fa79bcd7946acb592602d upstream.

A flush request is usually issued in transaction commit code path, so
using GFP_KERNEL to allocate memory for flush request bio falls into
the classic deadlock issue.

This is suitable for any -stable kernel to which it applies as it
avoids a possible deadlock.

Signed-off-by: Shaohua Li <shli@...ionio.com>
Signed-off-by: NeilBrown <neilb@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/md.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -452,7 +452,7 @@ static void submit_flushes(struct work_s
 			atomic_inc(&rdev->nr_pending);
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
-			bi = bio_alloc_mddev(GFP_KERNEL, 0, mddev);
+			bi = bio_alloc_mddev(GFP_NOIO, 0, mddev);
 			bi->bi_end_io = md_end_flush;
 			bi->bi_private = rdev;
 			bi->bi_bdev = rdev->bdev;


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