linux-kernel - Re: [PATCH v2 2/3] block: don't delete queue kobject before its children

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Date:   Tue, 30 Nov 2021 07:45:57 +0100
From:   Hannes Reinecke <hare@...e.de>
To:     Eric Biggers <ebiggers@...nel.org>, linux-block@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-mmc@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bart Van Assche <bvanassche@....org>
Subject: Re: [PATCH v2 2/3] block: don't delete queue kobject before its
 children

On 11/30/21 5:03 AM, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
> 
> kobjects aren't supposed to be deleted before their child kobjects are
> deleted.  Apparently this is usually benign; however, a WARN will be
> triggered if one of the child kobjects has a named attribute group:
> 
>      sysfs group 'modes' not found for kobject 'crypto'
>      WARNING: CPU: 0 PID: 1 at fs/sysfs/group.c:278 sysfs_remove_group+0x72/0x80
>      ...
>      Call Trace:
>        sysfs_remove_groups+0x29/0x40 fs/sysfs/group.c:312
>        __kobject_del+0x20/0x80 lib/kobject.c:611
>        kobject_cleanup+0xa4/0x140 lib/kobject.c:696
>        kobject_release lib/kobject.c:736 [inline]
>        kref_put include/linux/kref.h:65 [inline]
>        kobject_put+0x53/0x70 lib/kobject.c:753
>        blk_crypto_sysfs_unregister+0x10/0x20 block/blk-crypto-sysfs.c:159
>        blk_unregister_queue+0xb0/0x110 block/blk-sysfs.c:962
>        del_gendisk+0x117/0x250 block/genhd.c:610
> 
> Fix this by moving the kobject_del() and the corresponding
> kobject_uevent() to the correct place.
> 
> Fixes: 2c2086afc2b8 ("block: Protect less code with sysfs_lock in blk_{un,}register_queue()")
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> ---
>   block/blk-sysfs.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@...e.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@...e.de                              +49 911 74053 688
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