6.12-stable review patch. If anyone has any objections, please let me know.
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From: Daniel Wagner wagi@kernel.org
commit a9ae6fe1c319c4776c2b11e85e15109cd3f04076 upstream.
The fallback code in blk_mq_map_hw_queues is original from blk_mq_pci_map_queues and was added to handle the case where pci_irq_get_affinity will return NULL for !SMP configuration.
blk_mq_map_hw_queues replaces besides blk_mq_pci_map_queues also blk_mq_virtio_map_queues which used to use blk_mq_map_queues for the fallback.
It's possible to use blk_mq_map_queues for both cases though. blk_mq_map_queues creates the same map as blk_mq_clear_mq_map for !SMP that is CPU 0 will be mapped to hctx 0.
The WARN_ON_ONCE has to be dropped for virtio as the fallback is also taken for certain configuration on default. Though there is still a WARN_ON_ONCE check in lib/group_cpus.c:
WARN_ON(nr_present + nr_others < numgrps);
which will trigger if the caller tries to create more hardware queues than CPUs. It tests the same as the WARN_ON_ONCE in blk_mq_pci_map_queues did.
Fixes: a5665c3d150c ("virtio: blk/scsi: replace blk_mq_virtio_map_queues with blk_mq_map_hw_queues") Reported-by: Steven Rostedt rostedt@goodmis.org Closes: https://lore.kernel.org/all/20250122093020.6e8a4e5b@gandalf.local.home/ Signed-off-by: Daniel Wagner wagi@kernel.org Link: https://lore.kernel.org/r/20250123-fix-blk_mq_map_hw_queues-v1-1-08dbd01f2c3... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/blk-mq-cpumap.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/block/blk-mq-cpumap.c +++ b/block/blk-mq-cpumap.c @@ -87,7 +87,6 @@ void blk_mq_map_hw_queues(struct blk_mq_ return;
fallback: - WARN_ON_ONCE(qmap->nr_queues > 1); - blk_mq_clear_mq_map(qmap); + blk_mq_map_queues(qmap); } EXPORT_SYMBOL_GPL(blk_mq_map_hw_queues);