mm/swap: remove buggy cache->nr check in refill_swap_slots_cache

refill_swap_slots_cache is always called when cache->nr is 0.  So remove
such buggy and confusing check.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: David Howells <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: NeilBrown <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

mm/swap_slots.c

@@ -258,7 +258,7 @@ out_unlock:
 /* called with swap slot cache's alloc lock held */
 static int refill_swap_slots_cache(struct swap_slots_cache *cache)
 {
-	if (!use_swap_slot_cache || cache->nr)
+	if (!use_swap_slot_cache)
 		return 0;
 
 	cache->cur = 0;