From commit 20e4d81393196 (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: Christian Borntraeger borntraeger@de.ibm.com Cc: Christoph Hellwig hch@lst.de Cc: Stefan Haberland sth@linux.vnet.ibm.com Fixes: 20e4d81393196 ("blk-mq: simplify queue mapping & schedule with each possisble CPU") Cc: stable@vger.kernel.org Signed-off-by: Ming Lei ming.lei@redhat.com --- block/blk-mq.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c index f5c7dbcb954f..9b220dc415ac 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2432,6 +2432,8 @@ 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; } }