Patch "md:raid1: fix a dead loop when read from a WriteMostly disk" has been added to the 4.4-stable tree

Patch "md:raid1: fix a dead loop when read from a WriteMostly disk" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    md:raid1: fix a dead loop when read from a WriteMostly disk

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     md-raid1-fix-a-dead-loop-when-read-from-a-writemostly-disk.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 816b0acf3deb6d6be5d0519b286fdd4bafade905 Mon Sep 17 00:00:00 2001
From: Wei Fang <fangwei1@huawei.com>
Date: Mon, 21 Mar 2016 19:18:32 +0800
Subject: md:raid1: fix a dead loop when read from a WriteMostly disk

From: Wei Fang <fangwei1@huawei.com>

commit 816b0acf3deb6d6be5d0519b286fdd4bafade905 upstream.

If first_bad == this_sector when we get the WriteMostly disk
in read_balance(), valid disk will be returned with zero
max_sectors. It'll lead to a dead loop in make_request(), and
OOM will happen because of endless allocation of struct bio.

Since we can't get data from this disk in this case, so
continue for another disk.

Signed-off-by: Wei Fang <fangwei1@huawei.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/raid1.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -570,7 +570,7 @@ static int read_balance(struct r1conf *c
 			if (best_dist_disk < 0) {
 				if (is_badblock(rdev, this_sector, sectors,
 						&first_bad, &bad_sectors)) {
-					if (first_bad < this_sector)
+					if (first_bad <= this_sector)
 						/* Cannot use this */
 						continue;
 					best_good_sectors = first_bad - this_sector;


Patches currently in stable-queue which might be from fangwei1@huawei.com are

queue-4.4/md-raid1-fix-a-dead-loop-when-read-from-a-writemostly-disk.patch