Re: [PATCH] dm: fix unlocked test for dm_suspended_md

[Benjamin Marzinski <bmarzins@redhat.com>]

On Thu, Jan 08, 2026 at 08:55:08PM +0100, Mikulas Patocka wrote:
> The function dm_blk_report_zones tests if the device is suspended with
> the "dm_suspended_md" call. However, this function is called without
> holding any locks, so the device may be suspended just after it.
> 
> Move the call to dm_suspended_md after dm_get_live_table, so that the
> device can't be suspended after the suspended state was tested.
> 
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Fixes: 37f53a2c60d0 ("dm: fix dm_blk_report_zones")

Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
> 
> ---
>  drivers/md/dm-zone.c |    9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> Index: linux-2.6/drivers/md/dm-zone.c
> ===================================================================
> --- linux-2.6.orig/drivers/md/dm-zone.c	2026-01-06 15:55:41.000000000 +0100
> +++ linux-2.6/drivers/md/dm-zone.c	2026-01-06 22:55:36.000000000 +0100
> @@ -60,11 +60,13 @@ int dm_blk_report_zones(struct gendisk *
>  		 * Zone revalidation during __bind() is in progress, but this
>  		 * call is from a different process
>  		 */
> -		if (dm_suspended_md(md))
> -			return -EAGAIN;
> -
>  		map = dm_get_live_table(md, &srcu_idx);
>  		put_table = true;
> +
> +		if (dm_suspended_md(md)) {
> +			ret = -EAGAIN;
> +			goto do_put_table;
> +		}
>  	} else {
>  		/* Zone revalidation during __bind() */
>  		map = zone_revalidate_map;
> @@ -79,6 +81,7 @@ int dm_blk_report_zones(struct gendisk *
>  		ret = dm_blk_do_report_zones(md, map, nr_zones, &dm_args);
>  	}
>  
> +do_put_table:
>  	if (put_table)
>  		dm_put_live_table(md, srcu_idx);
>