cpumask is the list of CPUs present when the queue is built.
If a new CPU is hotplugged, this list is not updated,
and when the scheduler asks for a CPU id, blk_mq_hctx_next_cpu()
can return WORK_CPU_UNBOUND.
And in this case _blk_mq_run_hw_queue() can be executed by the new CPU
(that is not present in cpumask) and raises the following warning:
WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
cpu_online(hctx->next_cpu));
To fix this problem, this patch modifies blk_mq_hctx_next_cpu()
to only return a CPU id present in cpumask.
Signed-off-by: Laurent Vivier <lvivier@xxxxxxxxxx>
---
block/blk-mq.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4603b115e234..bdac1e654814 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1126,9 +1126,6 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
*/
static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
{
- if (hctx->queue->nr_hw_queues == 1)
- return WORK_CPU_UNBOUND;
-
if (--hctx->next_cpu_batch <= 0) {
int next_cpu;
--
2.13.5
