During the following test scenario:
- Offline a cpu
- load lpfc driver, which auto-discovers NVMe devices. For a new
nvme device, the lpfc/nvme_fc transport can request up to
num_online_cpus() worth of nr_hw_queues. The target in
this case allowed at least that many of nvme queues.
The system encountered the following crash:
BUG: unable to handle kernel paging request at 00003659d33953a8
...
Workqueue: nvme-wq nvme_fc_connect_ctrl_work [nvme_fc]
RIP: 0010:blk_mq_get_request+0x21d/0x3c0
...
Blk_mq_alloc_request_hctx+0xef/0x140
Nvme_alloc_request+0x32/0x80 [nvme_core]
__nvme_submit_sync_cmd+0x4a/0x1c0 [nvme_core]
Nvmf_connect_io_queue+0x130/0x1a0 [nvme_fabrics]
Nvme_fc_connect_io_queues+0x285/0x2b0 [nvme_fc]
Nvme_fc_create_association+0x0x8ea/0x9c0 [nvme_fc]
Nvme_fc_connect_ctrl_work+0x19/0x50 [nvme_fc]
...
There was a commit a while ago to simplify queue mapping which
replaced the use of cpumask_first() by cpumask_first_and().
The issue is if cpumask_first_and() does not find any _intersecting_ cpus,
it return's nr_cpu_id. nr_cpu_id isn't valid for the per_cpu_ptr index
which is done in __blk_mq_get_ctx().
Considered reverting back to cpumask_first(), but instead followed
logic in blk_mq_first_mapped_cpu() to check for nr_cpu_id before
calling cpumask_first().
Fixes: 20e4d8139319 ("blk-mq: simplify queue mapping & schedule with each possisble CPU")
Signed-off-by: Shagun Agrawal <shagun.agrawal@xxxxxxxxxxxx>
Signed-off-by: James Smart <jsmart2021@xxxxxxxxx>
CC: Christoph Hellwig <hch@xxxxxx>
---
block/blk-mq.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8538dc415499..0b06b4ea57f1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -461,6 +461,8 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
return ERR_PTR(-EXDEV);
}
cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
+ if (cpu >= nr_cpu_ids)
+ cpu = cpumask_first(alloc_data.hctx->cpumask);
alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
rq = blk_mq_get_request(q, NULL, &alloc_data);
--
2.13.7
