This is a note to let you know that I've just added the patch titled
blk-mq: prealloc tags when increase tagset nr_hw_queues
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
blk-mq-prealloc-tags-when-increase-tagset-nr_hw_queues.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7222657e51b5626d10154b3e48ad441c33b5da96 Mon Sep 17 00:00:00 2001
From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Date: Mon, 21 Aug 2023 17:56:02 +0800
Subject: blk-mq: prealloc tags when increase tagset nr_hw_queues
From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
commit 7222657e51b5626d10154b3e48ad441c33b5da96 upstream.
Just like blk_mq_alloc_tag_set(), it's better to prepare all tags before
using to map to queue ctxs in blk_mq_map_swqueue(), which now have to
consider empty set->tags[].
The good point is that we can fallback easily if increasing nr_hw_queues
fail, instead of just mapping to hctx[0] when fail in blk_mq_map_swqueue().
And the fallback path already has tags free & clean handling, so all
is good.
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230821095602.70742-3-chengming.zhou@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-mq.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4420,6 +4420,16 @@ static int blk_mq_realloc_tag_set_tags(s
sizeof(*set->tags));
kfree(set->tags);
set->tags = new_tags;
+
+ for (i = set->nr_hw_queues; i < new_nr_hw_queues; i++) {
+ if (!__blk_mq_alloc_map_and_rqs(set, i)) {
+ while (--i >= set->nr_hw_queues)
+ __blk_mq_free_map_and_rqs(set, i);
+ return -ENOMEM;
+ }
+ cond_resched();
+ }
+
done:
set->nr_hw_queues = new_nr_hw_queues;
return 0;
Patches currently in stable-queue which might be from zhouchengming@xxxxxxxxxxxxx are
queue-6.5/blk-mq-prealloc-tags-when-increase-tagset-nr_hw_queues.patch
queue-6.5/blk-mq-fix-tags-leak-when-shrink-nr_hw_queues.patch
queue-6.5/blk-mq-fix-tags-uaf-when-shrinking-q-nr_hw_queues.patch
