Commit 4c7ef92f authored by Li Nan's avatar Li Nan Committed by Jens Axboe
Browse files

blk-mq: check kobject state_in_sysfs before deleting in blk_mq_unregister_hctx 



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: 477e19de ("blk-mq: adjust debugfs and sysfs register when updating nr_hw_queues")
Signed-off-by: default avatarLi Nan <linan122@huawei.com>
Reviewed-by: default avatarYu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250826084854.1030545-1-linan666@huaweicloud.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d4399e6e

block/blk-mq-sysfs.c

+4 −2
Original line number Diff line number Diff line
@@ -150,8 +150,10 @@ static void blk_mq_unregister_hctx(struct blk_mq_hw_ctx *hctx) 
		return;



	hctx_for_each_ctx(hctx, ctx, i)

		if (ctx->kobj.state_in_sysfs)

			kobject_del(&ctx->kobj);



	if (hctx->kobj.state_in_sysfs)

		kobject_del(&hctx->kobj);

}