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| author |   Ming Lei <ming.lei@redhat.com> | 2025-08-15 21:17:37 +0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2025-08-21 05:34:19 -0600 |
| commit | 2d82f3bd8910eb65e30bb2a3c9b945bfb3b6d661 (patch) | |
| tree | dd1836965ef0c7194a3a62ab7506aac0fa0fff59 /tools/perf/scripts/python/Perf-Trace-Util/lib | |
| parent | block: tone down bio_check_eod (diff) | |
| download | wireguard-linux-2d82f3bd8910eb65e30bb2a3c9b945bfb3b6d661.tar.xz wireguard-linux-2d82f3bd8910eb65e30bb2a3c9b945bfb3b6d661.zip | |
blk-mq: fix lockdep warning in __blk_mq_update_nr_hw_queues
Commit 5989bfe6ac6b ("block: restore two stage elevator switch while
running nr_hw_queue update") reintroduced a lockdep warning by calling
blk_mq_freeze_queue_nomemsave() before switching the I/O scheduler.
The function blk_mq_elv_switch_none() calls elevator_change_done().
Running this while the queue is frozen causes a lockdep warning.
Fix this by reordering the operations: first, switch the I/O scheduler
to 'none', and then freeze the queue. This ensures that elevator_change_done()
is not called on an already frozen queue. And this way is safe because
elevator_set_none() does freeze queue before switching to none.
Also we still have to rely on blk_mq_elv_switch_back() for switching
back, and it has to cover unfrozen queue case.
Cc: Nilay Shroff <nilay@linux.ibm.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Fixes: 5989bfe6ac6b ("block: restore two stage elevator switch while running nr_hw_queue update")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250815131737.331692-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'tools/perf/scripts/python/Perf-Trace-Util/lib')
0 files changed, 0 insertions, 0 deletions