Commit a1c735fb authored Apr 08, 2018 by Ming Lei Committed by Jens Axboe Apr 10, 2018

blk-mq: make sure that correct hctx->next_cpu is set



From commit 20e4d813 (blk-mq: simplify queue mapping & schedule
with each possisble CPU), one hctx can be mapped from all offline CPUs,
then hctx->next_cpu can be set as wrong.

This patch fixes this issue by making hctx->next_cpu pointing to the
first CPU in hctx->cpumask if all CPUs in hctx->cpumask are offline.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Fixes: 20e4d813 ("blk-mq: simplify queue mapping & schedule with each possisble CPU")
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent bdac616d

block/blk-mq.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -2431,6 +2431,8 @@ static void blk_mq_map_swqueue(struct request_queue *q)
		*/
		hctx->next_cpu = cpumask_first_and(hctx->cpumask,
		cpu_online_mask);
		if (hctx->next_cpu >= nr_cpu_ids)
		hctx->next_cpu = cpumask_first(hctx->cpumask);
		hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
		}
		}

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