From: Ming Lei <ming.lei@redhat.com>
Date: Thu, 2 Dec 2021 17:07:16 +0800
Subject: [PATCH] blk-mq: check q->poll_stat in queue_poll_stat_show
Git-commit: 18d78171c061889a9a43152f60d6a27a10fc7656
Patch-mainline: v5.17-rc1
References: jsc#PED-1183
Without checking q->poll_stat in queue_poll_stat_show(), kernel panic
may be caused if q->poll_stat isn't allocated.
Fixes: 48b5c1fbcd8c ("block: only allocate poll_stats if there's a user of them")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20211202090716.3292244-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
block/blk-mq-debugfs.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 7f27dca3a45e..3a790eb4995c 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -30,6 +30,9 @@ static int queue_poll_stat_show(void *data, struct seq_file *m)
struct request_queue *q = data;
int bucket;
+ if (!q->poll_stat)
+ return 0;
+
for (bucket = 0; bucket < (BLK_MQ_POLL_STATS_BKTS / 2); bucket++) {
seq_printf(m, "read (%d Bytes): ", 1 << (9 + bucket));
print_stat(m, &q->poll_stat[2 * bucket]);
--
2.35.3