linux-kernel - Re: [PATCH v7 1/4] md: delete md_redundancy

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Message-Id: <0ef2d9c7-62c7-4e3e-9eab-48cbb2d7e6fd@fnnas.com>
Date: Tue, 28 Oct 2025 19:57:05 +0800
From: "Yu Kuai" <yukuai@...as.com>
To: <linan122@...wei.com>, <corbet@....net>, <song@...nel.org>, 
	<hare@...e.de>, <xni@...hat.com>
Cc: <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>, 
	<linux-raid@...r.kernel.org>, <linan666@...weicloud.com>, 
	<yangerkun@...wei.com>, <yi.zhang@...wei.com>
Subject: Re: [PATCH v7 1/4] md: delete md_redundancy_group when array is becoming inactive

在 2025/10/27 15:29, linan122@...wei.com 写道:

> From: Li Nan <linan122@...wei.com>
>
> 'md_redundancy_group' are created in md_run() and deleted in del_gendisk(),
> but these are not paired. Writing inactive/active to sysfs array_state can
> trigger md_run() multiple times without del_gendisk(), leading to
> duplicate creation as below:
>
>   sysfs: cannot create duplicate filename '/devices/virtual/block/md0/md/sync_action'
>   Call Trace:
>    dump_stack_lvl+0x9f/0x120
>    dump_stack+0x14/0x20
>    sysfs_warn_dup+0x96/0xc0
>    sysfs_add_file_mode_ns+0x19c/0x1b0
>    internal_create_group+0x213/0x830
>    sysfs_create_group+0x17/0x20
>    md_run+0x856/0xe60
>    ? __x64_sys_openat+0x23/0x30
>    do_md_run+0x26/0x1d0
>    array_state_store+0x559/0x760
>    md_attr_store+0xc9/0x1e0
>    sysfs_kf_write+0x6f/0xa0
>    kernfs_fop_write_iter+0x141/0x2a0
>    vfs_write+0x1fc/0x5a0
>    ksys_write+0x79/0x180
>    __x64_sys_write+0x1d/0x30
>    x64_sys_call+0x2818/0x2880
>    do_syscall_64+0xa9/0x580
>    entry_SYSCALL_64_after_hwframe+0x4b/0x53
>   md: cannot register extra attributes for md0
>
> Creation of it depends on 'pers', its lifecycle cannot be aligned with
> gendisk. So fix this issue by triggering 'md_redundancy_group' deletion
> when the array is becoming inactive.
>
> Fixes: 790abe4d77af ("md: remove/add redundancy group only in level change")
> Signed-off-by: Li Nan <linan122@...wei.com>
> ---
>   drivers/md/md.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index fa13eb02874e..f6fd55a1637b 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -6878,6 +6878,10 @@ static int do_md_stop(struct mddev *mddev, int mode)
>   		if (!md_is_rdwr(mddev))
>   			set_disk_ro(disk, 0);
>   
> +		if (mode == 2 && mddev->pers->sync_request &&
> +		    mddev->to_remove == NULL)
> +			mddev->to_remove = &md_redundancy_group;
> +
>   		__md_stop_writes(mddev);
>   		__md_stop(mddev);
>   

Reviewed-by: Yu Kuai <yukuai@...as.com>