Re: [PATCH V5 5/9] null_blk: free zones array on device power-off

[Nilay Shroff]

On 7/14/26 9:48 AM, Zizhi Wo wrote:
> null_init_zoned_dev() allocates dev->zones when a zoned device is powered
> on, but null_del_dev() never frees it on power-off; dev->zones is only
> freed later in null_free_dev(), when the configfs directory is removed. If
> the device is powered off and then on again, null_init_zoned_dev()
> allocates a new array and overwrites the dev->zones pointer, leaking the
> previous allocation each power cycle.
>
> Free dev->zones in null_del_dev() via null_free_zoned_dev() to solve it.
> And calling null_free_zoned_dev() in null_free_dev() is no longer necessary
> because every caller already invokes null_del_dev() first: via
> nullb_group_drop_item() before nullb_device_release(), in the
> null_add_dev() error path of null_create_dev(), and in null_destroy_dev().
> Remove the redundant call.
>
> And take &lock around zone_cond_store() in the two store wrappers to
> serialize dev->zones check-and-deref against its alloc/free, which already
> run under &lock. The reason there was no problem before is that only
> nullb_device_release() or null_exit() frees the dev->zones, which
> guarantees that subsequent users won't access the configfs interface.
>
> Fixes: ca4b2a011948 ("null_blk: add zone support")
> Assisted-by: Claude-Code:GLM-5.2
> Signed-off-by: Zizhi Wo<wozizhi@xxxxxxxxxx>

Looks good to me.

Reviewed-by: Nilay Shroff <nilay@xxxxxxxxxxxxx>