From: Hou Tao <houtao1@huawei.com>
To: Jens Axboe <axboe@kernel.dk>, Ming Lei <ming.lei@redhat.com>
Cc: <linux-block@vger.kernel.org>
Subject: [PATCH] block: check the existence of tags[hctx_idx] in blk_mq_clear_rq_mapping()
Date: Thu, 9 Sep 2021 17:00:54 +0800 [thread overview]
Message-ID: <20210909090054.492923-1-houtao1@huawei.com> (raw)
According to commit 4412efecf7fd ("Revert "blk-mq: remove code for
dealing with remapping queue""), for some devices queue hctx may not
being mapped, and tagset->tags[hctx_idx] will be released and be NULL.
If an IO scheduler is used on these devices, blk_mq_clear_rq_mapping()
will be called for all hctxs in blk_mq_sched_free_requests() during
scheduler switch, and these will be oops. So checking the existence of
tags[hctx_idx] before going on in blk_mq_clear_rq_mapping().
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
block/blk-mq.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 65d3a63aecc6..c3d701f44e49 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2297,6 +2297,10 @@ static void blk_mq_clear_rq_mapping(struct blk_mq_tag_set *set,
struct page *page;
unsigned long flags;
+ /* If the hctx is unmapped, drv_tags may be NULL */
+ if (!drv_tags)
+ return;
+
list_for_each_entry(page, &tags->page_list, lru) {
unsigned long start = (unsigned long)page_address(page);
unsigned long end = start + order_to_size(page->private);
--
2.29.2
next reply other threads:[~2021-09-09 8:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-09 9:00 Hou Tao [this message]
2021-09-09 9:19 ` [PATCH] block: check the existence of tags[hctx_idx] in blk_mq_clear_rq_mapping() Ming Lei
2021-09-09 11:14 ` Hou Tao
2021-09-13 1:43 ` Ming Lei
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