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From: Hannes Reinecke <hare@suse.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>,
	Daniel Wagner <daniel.wagner@suse.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
	Wen Xiong <wenxiong@us.ibm.com>, Hannes Reinecke <hare@suse.de>
Subject: [PATCH] blk-mq: don't allocate requests when all cpus in a hctx are offline
Date: Wed, 30 Jun 2021 12:03:42 +0200	[thread overview]
Message-ID: <20210630100342.1100-1-hare@suse.de> (raw)

When all CPUs in a hctx are offline in blk_mq_alloc_request_hctx() we should
not try to allocate the request, as we'll fail later on in blk_mq_get_tag() anyway.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-mq.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index f11d4018ce2e..1622d0cabe3a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -468,13 +468,16 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
 	data.hctx = q->queue_hw_ctx[hctx_idx];
 	if (!blk_mq_hw_queue_mapped(data.hctx))
 		goto out_queue_exit;
+	ret = -EWOULDBLOCK;
+	/* all cpus in the hctx are offline, don't try to allocate a tag */
 	cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
+	if (unlikely(cpu >= nr_cpu_ids))
+		goto out_queue_exit;
 	data.ctx = __blk_mq_get_ctx(q, cpu);
 
 	if (!q->elevator)
 		blk_mq_tag_busy(data.hctx);
 
-	ret = -EWOULDBLOCK;
 	tag = blk_mq_get_tag(&data);
 	if (tag == BLK_MQ_NO_TAG)
 		goto out_queue_exit;
-- 
2.29.2


WARNING: multiple messages have this Message-ID (diff)
From: Hannes Reinecke <hare@suse.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>,
	Daniel Wagner <daniel.wagner@suse.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
	Wen Xiong <wenxiong@us.ibm.com>, Hannes Reinecke <hare@suse.de>
Subject: [PATCH] blk-mq: don't allocate requests when all cpus in a hctx are offline
Date: Wed, 30 Jun 2021 12:03:42 +0200	[thread overview]
Message-ID: <20210630100342.1100-1-hare@suse.de> (raw)

When all CPUs in a hctx are offline in blk_mq_alloc_request_hctx() we should
not try to allocate the request, as we'll fail later on in blk_mq_get_tag() anyway.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-mq.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index f11d4018ce2e..1622d0cabe3a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -468,13 +468,16 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
 	data.hctx = q->queue_hw_ctx[hctx_idx];
 	if (!blk_mq_hw_queue_mapped(data.hctx))
 		goto out_queue_exit;
+	ret = -EWOULDBLOCK;
+	/* all cpus in the hctx are offline, don't try to allocate a tag */
 	cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
+	if (unlikely(cpu >= nr_cpu_ids))
+		goto out_queue_exit;
 	data.ctx = __blk_mq_get_ctx(q, cpu);
 
 	if (!q->elevator)
 		blk_mq_tag_busy(data.hctx);
 
-	ret = -EWOULDBLOCK;
 	tag = blk_mq_get_tag(&data);
 	if (tag == BLK_MQ_NO_TAG)
 		goto out_queue_exit;
-- 
2.29.2


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             reply	other threads:[~2021-06-30 10:03 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-30 10:03 Hannes Reinecke [this message]
2021-06-30 10:03 ` [PATCH] blk-mq: don't allocate requests when all cpus in a hctx are offline Hannes Reinecke
2021-06-30 10:13 ` Ming Lei
2021-06-30 10:13   ` Ming Lei

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