Commit 49b2fe4b authored Mar 21, 2016 by Wei Fang Committed by Greg Kroah-Hartman May 02, 2017

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



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>

parent 28320756

drivers/md/raid1.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -570,7 +570,7 @@ static int read_balance(struct r1conf conf, struct r1bio r1_bio, int *max_sect
		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;