linux-kernel - [PATCH mm-new] mm: optimize lru_note_cost() by adding lru_note_cost_unlock

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Message-ID: <dbf9352a-1ed9-a021-c0c7-9309ac73e174@google.com>
Date: Tue, 15 Jul 2025 13:48:25 -0700 (PDT)
From: Hugh Dickins <hughd@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
cc: Hugh Dickins <hughd@...gle.com>, Shakeel Butt <shakeel.butt@...ux.dev>, 
    Roman Gushchin <roman.gushchin@...ux.dev>, 
    Johannes Weiner <hannes@...xchg.org>, 
    Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
    Michal Hocko <mhocko@...nel.org>, David Hildenbrand <david@...hat.com>, 
    linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH mm-new] mm: optimize lru_note_cost() by adding
 lru_note_cost_unlock_irq() fix

Delete the comment from above the deleted spin_lock_irq(): it was all to
justify the first iteration's spin_lock_irq(), none suitable for moving
down to where the parent's spin_lock_irq() is now done.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
---
Thank you all for the warm reception! Sorry, I missed this deletion.

 mm/swap.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index 37053f222a6e..3632dd061beb 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -259,13 +259,6 @@ void lru_note_cost_unlock_irq(struct lruvec *lruvec, bool file,
 	for (;;) {
 		unsigned long lrusize;
 
-		/*
-		 * Hold lruvec->lru_lock is safe here, since
-		 * 1) The pinned lruvec in reclaim, or
-		 * 2) From a pre-LRU page during refault (which also holds the
-		 *    rcu lock, so would be safe even if the page was on the LRU
-		 *    and could move simultaneously to a new lruvec).
-		 */
 		/* Record cost event */
 		if (file)
 			lruvec->file_cost += cost;
-- 
2.43.0