linux-kernel - Re: [PATCH] blk-mq: check kobject state_in_sysfs before deleting in blk_mq_unregister

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Message-ID: <b5f385bc-5e16-2a79-f997-5fd697f2a38a@huaweicloud.com>
Date: Wed, 27 Aug 2025 11:22:06 +0800
From: Li Nan <linan666@...weicloud.com>
To: Ming Lei <ming.lei@...hat.com>, Yu Kuai <yukuai1@...weicloud.com>
Cc: linan666@...weicloud.com, axboe@...nel.dk, jianchao.w.wang@...cle.com,
 linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
 yangerkun@...wei.com, yi.zhang@...wei.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH] blk-mq: check kobject state_in_sysfs before deleting in
 blk_mq_unregister_hctx



在 2025/8/27 9:35, Ming Lei 写道:
> On Wed, Aug 27, 2025 at 09:04:45AM +0800, Yu Kuai wrote:
>> Hi,
>>
>> 在 2025/08/27 8:58, Ming Lei 写道:
>>> On Tue, Aug 26, 2025 at 04:48:54PM +0800, linan666@...weicloud.com wrote:
>>>> From: Li Nan <linan122@...wei.com>
>>>>
>>>> In __blk_mq_update_nr_hw_queues() the return value of
>>>> blk_mq_sysfs_register_hctxs() is not checked. If sysfs creation for hctx
>>>
>>> Looks we should check its return value and handle the failure in both
>>> the call site and blk_mq_sysfs_register_hctxs().
>>
>>  From __blk_mq_update_nr_hw_queues(), the old hctxs is already
>> unregistered, and this function is void, we failed to register new hctxs
>> because of memory allocation failure. I really don't know how to handle
>> the failure here, do you have any suggestions?
> 
> It is out of memory, I think it is fine to do whatever to leave queue state
> intact instead of making it `partial workable`, such as:
> 
> - try update nr_hw_queues to 1
> 
> - if it still fails, delete disk & mark queue as dead if disk is attached
> 

If we ignore these non-critical sysfs creation failures, the disk remains 
usable with no loss of functionality. Deleting the disk seems to escalate
the error?

-- 
Thanks,
Nan