mm/swapfile: use plist_for_each_entry in __folio_throttle_swaprate

The loop breaks immediately after finding the first swap device and
never modifies the list. Replace plist_for_each_entry_safe() with
plist_for_each_entry() and remove the unused next variable.

Link: https://lkml.kernel.org/r/20251127100303.783198-3-youngjun.park@lge.com
Signed-off-by: Youngjun Park <youngjun.park@lge.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: youngjuni

mm/swapfile.c

@@ -4023,7 +4023,7 @@ static bool __has_usable_swap(void)
 
 void __folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
 {
-	struct swap_info_struct *si, *next;
+	struct swap_info_struct *si;
 
 	if (!(gfp & __GFP_IO))
 		return;
@@ -4042,8 +4042,7 @@ void __folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
 		return;
 
 	spin_lock(&swap_avail_lock);
-	plist_for_each_entry_safe(si, next, &swap_avail_head,
-				  avail_list) {
+	plist_for_each_entry(si, &swap_avail_head, avail_list) {
 		if (si->bdev) {
 			blkcg_schedule_throttle(si->bdev->bd_disk, true);
 			break;