This is a note to let you know that I've just added the patch titled
block: drain queue before waiting for q_usage_counter becoming zero
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: block-drain-queue-before-waiting-for-q_usage_counter-becoming-zero.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Wed Feb 28 16:23:28 CET 2018
From: Ming Lei ming.lei@redhat.com Date: Thu, 30 Nov 2017 07:56:35 +0800 Subject: block: drain queue before waiting for q_usage_counter becoming zero
From: Ming Lei ming.lei@redhat.com
[ Upstream commit 454be724f6f99cc7e7bbf15067128be9868186c6 ]
Now we track legacy requests with .q_usage_counter in commit 055f6e18e08f ("block: Make q_usage_counter also track legacy requests"), but that commit never runs and drains legacy queue before waiting for this counter becoming zero, then IO hang is caused in the test of pulling disk during IO.
This patch fixes the issue by draining requests before waiting for q_usage_counter becoming zero, both Mauricio and chenxiang reported this issue, and observed that it can be fixed by this patch.
Link: https://marc.info/?l=linux-block&m=151192424731797&w=2 Fixes: 055f6e18e08f("block: Make q_usage_counter also track legacy requests") Cc: Wen Xiong wenxiong@us.ibm.com Tested-by: "chenxiang (M)" chenxiang66@hisilicon.com Tested-by: Mauricio Faria de Oliveira mauricfo@linux.vnet.ibm.com Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/blk-core.c | 9 +++++++-- block/blk-mq.c | 2 ++ block/blk.h | 2 ++ 3 files changed, 11 insertions(+), 2 deletions(-)
--- a/block/blk-core.c +++ b/block/blk-core.c @@ -531,6 +531,13 @@ static void __blk_drain_queue(struct req } }
+void blk_drain_queue(struct request_queue *q) +{ + spin_lock_irq(q->queue_lock); + __blk_drain_queue(q, true); + spin_unlock_irq(q->queue_lock); +} + /** * blk_queue_bypass_start - enter queue bypass mode * @q: queue of interest @@ -655,8 +662,6 @@ void blk_cleanup_queue(struct request_qu */ blk_freeze_queue(q); spin_lock_irq(lock); - if (!q->mq_ops) - __blk_drain_queue(q, true); queue_flag_set(QUEUE_FLAG_DEAD, q); spin_unlock_irq(lock);
--- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -159,6 +159,8 @@ void blk_freeze_queue(struct request_que * exported to drivers as the only user for unfreeze is blk_mq. */ blk_freeze_queue_start(q); + if (!q->mq_ops) + blk_drain_queue(q); blk_mq_freeze_queue_wait(q); }
--- a/block/blk.h +++ b/block/blk.h @@ -362,4 +362,6 @@ static inline void blk_queue_bounce(stru } #endif /* CONFIG_BOUNCE */
+extern void blk_drain_queue(struct request_queue *q); + #endif /* BLK_INTERNAL_H */
Patches currently in stable-queue which might be from ming.lei@redhat.com are
queue-4.14/block-drain-queue-before-waiting-for-q_usage_counter-becoming-zero.patch