Patch "blk-mq: register cpuhp callback after hctx is added to xarray table" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    blk-mq: register cpuhp callback after hctx is added to xarray table

to the 6.1-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-register-cpuhp-callback-after-hctx-is-added-t.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 82c7dab53daf84bf1c3ec90df93dc0350cdca4e5
Author: Ming Lei <ming.lei@xxxxxxxxxx>
Date:   Fri Dec 6 19:16:06 2024 +0800

    blk-mq: register cpuhp callback after hctx is added to xarray table
    
    [ Upstream commit 4bf485a7db5d82ddd0f3ad2b299893199090375e ]
    
    We need to retrieve 'hctx' from xarray table in the cpuhp callback, so the
    callback should be registered after this 'hctx' is added to xarray table.
    
    Cc: Reinette Chatre <reinette.chatre@xxxxxxxxx>
    Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
    Cc: Peter Newman <peternewman@xxxxxxxxxx>
    Cc: Babu Moger <babu.moger@xxxxxxx>
    Cc: Luck Tony <tony.luck@xxxxxxxxx>
    Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
    Tested-by: Tony Luck <tony.luck@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20241206111611.978870-2-ming.lei@xxxxxxxxxx
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index a5ed12bd2b0a..373a67a630f3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3671,16 +3671,11 @@ static int blk_mq_init_hctx(struct request_queue *q,
 {
 	hctx->queue_num = hctx_idx;
 
-	if (!(hctx->flags & BLK_MQ_F_STACKING))
-		cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
-				&hctx->cpuhp_online);
-	cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
-
 	hctx->tags = set->tags[hctx_idx];
 
 	if (set->ops->init_hctx &&
 	    set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
-		goto unregister_cpu_notifier;
+		goto fail;
 
 	if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
 				hctx->numa_node))
@@ -3689,6 +3684,11 @@ static int blk_mq_init_hctx(struct request_queue *q,
 	if (xa_insert(&q->hctx_table, hctx_idx, hctx, GFP_KERNEL))
 		goto exit_flush_rq;
 
+	if (!(hctx->flags & BLK_MQ_F_STACKING))
+		cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
+				&hctx->cpuhp_online);
+	cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
+
 	return 0;
 
  exit_flush_rq:
@@ -3697,8 +3697,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
  exit_hctx:
 	if (set->ops->exit_hctx)
 		set->ops->exit_hctx(hctx, hctx_idx);
- unregister_cpu_notifier:
-	blk_mq_remove_cpuhp(hctx);
+ fail:
 	return -1;
 }