From: Jens Axboe <axboe@fb.com>
Date: Thu, 26 Jan 2017 21:52:20 +0000 (-0700)
Subject: blk-mq-sched: check for successful allocation before assigning tag
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b48fda0976a802e0fe4fc0bedefb7cf380ec6426;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

blk-mq-sched: check for successful allocation before assigning tag

We don't trigger this from the normal IO path, since we always use
blocking allocations from there. But Bart saw it testing multipath
dm, since that is a heavy user of atomic request allocations in
the map and clone path.

Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 56b92db944ae..4cee060a292d 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -134,7 +134,8 @@ struct request *blk_mq_sched_get_request(struct request_queue *q,
 			rq = __blk_mq_alloc_request(data, op);
 	} else {
 		rq = __blk_mq_alloc_request(data, op);
-		data->hctx->tags->rqs[rq->tag] = rq;
+		if (rq)
+			data->hctx->tags->rqs[rq->tag] = rq;
 	}
 
 	if (rq) {