4.16-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei ming.lei@redhat.com
commit a1c735fb790745f94a359df45c11df4a69760389 upstream.
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: 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: 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 Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- block/blk-mq.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2439,6 +2439,8 @@ static void blk_mq_map_swqueue(struct re */ 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; } }