mm/swap: remove boilerplate

Remove boilerplate by using a macro to choose the corresponding lock and
handler for each folio_batch in cpu_fbatches.

[yuzhao@google.com: handle zero-length local_lock_t]
  Link: https://lkml.kernel.org/r/Zq_0X04WsqgUnz30@google.com
[yuzhao@google.com: fix "BUG: using smp_processor_id() in preemptible"]
  Link: https://lkml.kernel.org/r/ZqNHHMiHn-9vy_II@google.com
Link: https://lkml.kernel.org/r/20240711021317.596178-6-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Tested-by: Hugh Dickins <hughd@google.com>
Cc: Barry Song <21cnbao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap.c

@@ -220,16 +220,43 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn)
 	folios_put(fbatch);
 }
 
-static void folio_batch_add_and_move(struct folio_batch *fbatch,
+static void __folio_batch_add_and_move(struct folio_batch __percpu *fbatch,
-		struct folio *folio, move_fn_t move_fn)
+		struct folio *folio, move_fn_t move_fn,
+		bool on_lru, bool disable_irq)
 {
-	if (folio_batch_add(fbatch, folio) && !folio_test_large(folio) &&
+	unsigned long flags;
-	    !lru_cache_disabled())
-		return;
 
-	folio_batch_move_lru(fbatch, move_fn);
+	folio_get(folio);
+
+	if (on_lru && !folio_test_clear_lru(folio)) {
+		folio_put(folio);
+		return;
+	}
+
+	if (disable_irq)
+		local_lock_irqsave(&cpu_fbatches.lock_irq, flags);
+	else
+		local_lock(&cpu_fbatches.lock);
+
+	if (!folio_batch_add(this_cpu_ptr(fbatch), folio) || folio_test_large(folio) ||
+	    lru_cache_disabled())
+		folio_batch_move_lru(this_cpu_ptr(fbatch), move_fn);
+
+	if (disable_irq)
+		local_unlock_irqrestore(&cpu_fbatches.lock_irq, flags);
+	else
+		local_unlock(&cpu_fbatches.lock);
 }
 
+#define folio_batch_add_and_move(folio, op, on_lru)						\
+	__folio_batch_add_and_move(								\
+		&cpu_fbatches.op,								\
+		folio,										\
+		op,										\
+		on_lru,										\
+		offsetof(struct cpu_fbatches, op) >= offsetof(struct cpu_fbatches, lock_irq)	\
+	)
+
 static void lru_move_tail(struct lruvec *lruvec, struct folio *folio)
 {
 	if (folio_test_unevictable(folio))
@@ -250,23 +277,11 @@ static void lru_move_tail(struct lruvec *lruvec, struct folio *folio)
  */
 void folio_rotate_reclaimable(struct folio *folio)
 {
-	struct folio_batch *fbatch;
-	unsigned long flags;
-
 	if (folio_test_locked(folio) || folio_test_dirty(folio) ||
 	    folio_test_unevictable(folio))
 		return;
 
-	folio_get(folio);
+	folio_batch_add_and_move(folio, lru_move_tail, true);
-	if (!folio_test_clear_lru(folio)) {
-		folio_put(folio);
-		return;
-	}
-
-	local_lock_irqsave(&cpu_fbatches.lock_irq, flags);
-	fbatch = this_cpu_ptr(&cpu_fbatches.lru_move_tail);
-	folio_batch_add_and_move(fbatch, folio, lru_move_tail);
-	local_unlock_irqrestore(&cpu_fbatches.lock_irq, flags);
 }
 
 void lru_note_cost(struct lruvec *lruvec, bool file,
@@ -355,21 +370,10 @@ static void folio_activate_drain(int cpu)
 
 void folio_activate(struct folio *folio)
 {
-	struct folio_batch *fbatch;
-
 	if (folio_test_active(folio) || folio_test_unevictable(folio))
 		return;
 
-	folio_get(folio);
+	folio_batch_add_and_move(folio, lru_activate, true);
-	if (!folio_test_clear_lru(folio)) {
-		folio_put(folio);
-		return;
-	}
-
-	local_lock(&cpu_fbatches.lock);
-	fbatch = this_cpu_ptr(&cpu_fbatches.lru_activate);
-	folio_batch_add_and_move(fbatch, folio, lru_activate);
-	local_unlock(&cpu_fbatches.lock);
 }
 
 #else
@@ -513,8 +517,6 @@ EXPORT_SYMBOL(folio_mark_accessed);
  */
 void folio_add_lru(struct folio *folio)
 {
-	struct folio_batch *fbatch;
-
 	VM_BUG_ON_FOLIO(folio_test_active(folio) &&
 			folio_test_unevictable(folio), folio);
 	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
@@ -524,11 +526,7 @@ void folio_add_lru(struct folio *folio)
 	    lru_gen_in_fault() && !(current->flags & PF_MEMALLOC))
 		folio_set_active(folio);
 
-	folio_get(folio);
+	folio_batch_add_and_move(folio, lru_add, false);
-	local_lock(&cpu_fbatches.lock);
-	fbatch = this_cpu_ptr(&cpu_fbatches.lru_add);
-	folio_batch_add_and_move(fbatch, folio, lru_add);
-	local_unlock(&cpu_fbatches.lock);
 }
 EXPORT_SYMBOL(folio_add_lru);
 
@@ -702,22 +700,11 @@ void lru_add_drain_cpu(int cpu)
  */
 void deactivate_file_folio(struct folio *folio)
 {
-	struct folio_batch *fbatch;
-
 	/* Deactivating an unevictable folio will not accelerate reclaim */
 	if (folio_test_unevictable(folio))
 		return;
 
-	folio_get(folio);
+	folio_batch_add_and_move(folio, lru_deactivate_file, true);
-	if (!folio_test_clear_lru(folio)) {
-		folio_put(folio);
-		return;
-	}
-
-	local_lock(&cpu_fbatches.lock);
-	fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate_file);
-	folio_batch_add_and_move(fbatch, folio, lru_deactivate_file);
-	local_unlock(&cpu_fbatches.lock);
 }
 
 /*
@@ -730,21 +717,10 @@ void deactivate_file_folio(struct folio *folio)
  */
 void folio_deactivate(struct folio *folio)
 {
-	struct folio_batch *fbatch;
-
 	if (folio_test_unevictable(folio) || !(folio_test_active(folio) || lru_gen_enabled()))
 		return;
 
-	folio_get(folio);
+	folio_batch_add_and_move(folio, lru_deactivate, true);
-	if (!folio_test_clear_lru(folio)) {
-		folio_put(folio);
-		return;
-	}
-
-	local_lock(&cpu_fbatches.lock);
-	fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate);
-	folio_batch_add_and_move(fbatch, folio, lru_deactivate);
-	local_unlock(&cpu_fbatches.lock);
 }
 
 /**
@@ -756,22 +732,11 @@ void folio_deactivate(struct folio *folio)
  */
 void folio_mark_lazyfree(struct folio *folio)
 {
-	struct folio_batch *fbatch;
-
 	if (!folio_test_anon(folio) || !folio_test_swapbacked(folio) ||
 	    folio_test_swapcache(folio) || folio_test_unevictable(folio))
 		return;
 
-	folio_get(folio);
+	folio_batch_add_and_move(folio, lru_lazyfree, true);
-	if (!folio_test_clear_lru(folio)) {
-		folio_put(folio);
-		return;
-	}
-
-	local_lock(&cpu_fbatches.lock);
-	fbatch = this_cpu_ptr(&cpu_fbatches.lru_lazyfree);
-	folio_batch_add_and_move(fbatch, folio, lru_lazyfree);
-	local_unlock(&cpu_fbatches.lock);
 }
 
 void lru_add_drain(void)