Re: [PATCH v2 2/2] mm/swap: Add lockdep for si->global_cluster_lock in swap_cluster_alloc_table()

[YoungJun Park]

On Mon, Mar 09, 2026 at 04:05:42PM +0800, Hui Zhu wrote:
> From: Hui Zhu <zhuhui@xxxxxxxxxx>
> 
> Add a lockdep_assert_held(&si->global_cluster_lock) in
> swap_cluster_alloc_table() for non-SWP_SOLIDSTATE devices.
> 
> The function already requires the caller to hold both ci->lock
> and percpu_swap_cluster.lock.
> And it also necessitates si->global_cluster_lock when the device is not
> SWP_SOLIDSTATE.
> 
> Adding this assertion ensures locking consistency and helps catch
> potential synchronization issues during development.
> Change the order of lockdep_assert_held() to match the actual lock
> acquisition order.
> 
> Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx>
> ---
>  mm/swapfile.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 3fc2eb30c187..b31b86263b89 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -476,8 +476,10 @@ swap_cluster_alloc_table(struct swap_info_struct *si,
>  	 * Only cluster isolation from the allocator does table allocation.
>  	 * Swap allocator uses percpu clusters and holds the local lock.
>  	 */
> -	lockdep_assert_held(&ci->lock);
>  	lockdep_assert_held(&this_cpu_ptr(&percpu_swap_cluster)->lock);
> +	if (!(si->flags & SWP_SOLIDSTATE))
> +		lockdep_assert_held(&si->global_cluster_lock);
> +	lockdep_assert_held(&ci->lock);
>  
>  	/* The cluster must be free and was just isolated from the free list. */
>  	VM_WARN_ON_ONCE(ci->flags || !cluster_is_empty(ci));
> -- 
> 2.43.0

The changes look good to me. Thanks!

Reviewed-by: Youngjun Park <youngjun.park@xxxxxxx>