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blk-mq: check kobject state_in_sysfs before deleting in blk_mq_unregister_hctx

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[ Upstream commit 4c7ef92f6d4d08a27d676e4c348f4e2922cab3ed ]

In __blk_mq_update_nr_hw_queues() the return value of
blk_mq_sysfs_register_hctxs() is not checked. If sysfs creation for hctx
fails, later changing the number of hw_queues or removing disk will
trigger the following warning:

  kernfs: can not remove 'nr_tags', no directory
  WARNING: CPU: 2 PID: 637 at fs/kernfs/dir.c:1707 kernfs_remove_by_name_ns+0x13f/0x160
  Call Trace:
   remove_files.isra.1+0x38/0xb0
   sysfs_remove_group+0x4d/0x100
   sysfs_remove_groups+0x31/0x60
   __kobject_del+0x23/0xf0
   kobject_del+0x17/0x40
   blk_mq_unregister_hctx+0x5d/0x80
   blk_mq_sysfs_unregister_hctxs+0x94/0xd0
   blk_mq_update_nr_hw_queues+0x124/0x760
   nullb_update_nr_hw_queues+0x71/0xf0 [null_blk]
   nullb_device_submit_queues_store+0x92/0x120 [null_blk]

kobjct_del() was called unconditionally even if sysfs creation failed.
Fix it by checkig the kobject creation statusbefore deleting it.

Fixes: 477e19dedc ("blk-mq: adjust debugfs and sysfs register when updating nr_hw_queues")
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250826084854.1030545-1-linan666@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Li Nan 2025-08-26 16:48:54 +08:00 committed by Greg Kroah-Hartman
parent 299cd1f5fd
commit 06c4826b1d
1 changed files with 4 additions and 2 deletions
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6
block/blk-mq-sysfs.c
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@ -150,9 +150,11 @@ static void blk_mq_unregister_hctx(struct blk_mq_hw_ctx *hctx)
return;
hctx_for_each_ctx(hctx, ctx, i)
kobject_del(&ctx->kobj);
if (ctx->kobj.state_in_sysfs)
kobject_del(&ctx->kobj);
kobject_del(&hctx->kobj);
if (hctx->kobj.state_in_sysfs)
kobject_del(&hctx->kobj);
}
static int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx)