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blk-mq: don't change nr_hw_queues and nr_maps for kdump kernel

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For most of ARCHs, 'nr_cpus=1' is passed for kdump kernel, so
nr_hw_queues for each mapping is supposed to be 1 already.

More importantly, this way may cause trouble for driver, because blk-mq and
driver see different queue mapping since driver should setup hardware
queue setting before calling into allocating blk-mq tagset.

So not overriding nr_hw_queues and nr_maps for kdump kernel.

Cc: Wen Xiong <wenxiong@us.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240228040857.306483-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2024-02-28 12:08:57 +08:00 committed by Jens Axboe
parent fb5d1d389c
commit ec30b461f3
1 changed files with 6 additions and 8 deletions
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14
block/blk-mq.c
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@ -4379,7 +4379,7 @@ static void blk_mq_update_queue_map(struct blk_mq_tag_set *set)
if (set->nr_maps == 1)
set->map[HCTX_TYPE_DEFAULT].nr_queues = set->nr_hw_queues;
if (set->ops->map_queues && !is_kdump_kernel()) {
if (set->ops->map_queues) {
int i;
/*
@ -4478,14 +4478,12 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
/*
* If a crashdump is active, then we are potentially in a very
* memory constrained environment. Limit us to 1 queue and
* 64 tags to prevent using too much memory.
* memory constrained environment. Limit us to 64 tags to prevent
* using too much memory.
*/
if (is_kdump_kernel()) {
set->nr_hw_queues = 1;
set->nr_maps = 1;
if (is_kdump_kernel())
set->queue_depth = min(64U, set->queue_depth);
}
/*
* There is no use for more h/w queues than cpus if we just have
* a single map
@ -4515,7 +4513,7 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
GFP_KERNEL, set->numa_node);
if (!set->map[i].mq_map)
goto out_free_mq_map;
set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
set->map[i].nr_queues = set->nr_hw_queues;
}
blk_mq_update_queue_map(set);