release/5.2.42/blk-mq-Keep-set-nr_hw_queues-and-set-map-.nr_queues-.patch

From 51013267bed327a68385ed5291e65e039044e5e2 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Mon, 9 Mar 2020 21:26:17 -0700
Subject: [PATCH] blk-mq: Keep set->nr_hw_queues and set->map[].nr_queues in
 sync

commit 6e66b49392419f3fe134e1be583323ef75da1e4b upstream.

blk_mq_map_queues() and multiple .map_queues() implementations expect that
set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the number of hardware
queues. Hence set .nr_queues before calling these functions. This patch
fixes the following kernel warning:

WARNING: CPU: 0 PID: 2501 at include/linux/cpumask.h:137
Call Trace:
 blk_mq_run_hw_queue+0x19d/0x350 block/blk-mq.c:1508
 blk_mq_run_hw_queues+0x112/0x1a0 block/blk-mq.c:1525
 blk_mq_requeue_work+0x502/0x780 block/blk-mq.c:775
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255

Fixes: ed76e329d74a ("blk-mq: abstract out queue map") # v5.0
Reported-by: syzbot+d44e1b26ce5c3e77458d@syzkaller.appspotmail.com
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Johannes Thumshirn <jth@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9a86ef77060e..94e04f269769 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3008,6 +3008,14 @@ static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
 
 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
 {
+	/*
+	 * blk_mq_map_queues() and multiple .map_queues() implementations
+	 * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the
+	 * number of hardware queues.
+	 */
+	if (set->nr_maps == 1)
+		set->map[HCTX_TYPE_DEFAULT].nr_queues = set->nr_hw_queues;
+
 	if (set->ops->map_queues && !is_kdump_kernel()) {
 		int i;
 
-- 
2.7.4