Re: [PATCH v2 2/5] mm, swap: Use SWP_SOLIDSTATE to determine if swap is rotational

[Baoquan He <bhe@redhat.com>]

On 10/31/25 at 03:50pm, Youngjun Park wrote:
> The current non rotational check is unreliable
> as the device's rotational status can be changed by a user via sysfs.
> 
> Use the more reliable SWP_SOLIDSTATE flag which is set at swapon time,
> to ensure the nr_rotate_swap count remains consistent.
> Plus, it is easy to read and simple.
> 
> Fixes: 81a0298bdfab ("mm, swap: don't use VMA based swap readahead if HDD is used as swap")
> Signed-off-by: Youngjun Park <youngjun.park@lge.com>
> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index ed2c8e4edb71..b7cde8ef6742 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -2913,7 +2913,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
>  	if (p->flags & SWP_CONTINUED)
>  		free_swap_count_continuations(p);
>  
> -	if (!p->bdev || !bdev_nonrot(p->bdev))
> +	if (!(p->flags & SWP_SOLIDSTATE))
>  		atomic_dec(&nr_rotate_swap);

Reviewed-by: Baoquan He <bhe@redhat.com>

>  
>  	mutex_lock(&swapon_mutex);
> -- 
> 2.34.1
>