+ mm-swap-take-folio-refcount-after-testing-the-lru-flag.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/swap: take folio refcount after testing the LRU flag
has been added to the -mm mm-unstable branch.  Its filename is
     mm-swap-take-folio-refcount-after-testing-the-lru-flag.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-take-folio-refcount-after-testing-the-lru-flag.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: yangge <yangge1116@126.com>
Subject: mm/swap: take folio refcount after testing the LRU flag
Date: Tue, 13 Aug 2024 17:52:23 +0800

Whoever passes a folio to __folio_batch_add_and_move() must hold a
reference, otherwise something else would already be messed up.  If the
folio is referenced, it will not be freed elsewhere, so we can safely
clear the folio's lru flag.  As discussed with David in [1], we should
take the reference after testing the LRU flag, not before.

Link: https://lore.kernel.org/lkml/d41865b4-d6fa-49ba-890a-921eefad27dd@redhat.com/ [1]
Link: https://lkml.kernel.org/r/1723542743-32179-1-git-send-email-yangge1116@126.com
Signed-off-by: yangge <yangge1116@126.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swap.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

--- a/mm/swap.c~mm-swap-take-folio-refcount-after-testing-the-lru-flag
+++ a/mm/swap.c
@@ -226,12 +226,10 @@ static void __folio_batch_add_and_move(s
 {
 	unsigned long flags;
 
-	folio_get(folio);
-
-	if (on_lru && !folio_test_clear_lru(folio)) {
-		folio_put(folio);
+	if (on_lru && !folio_test_clear_lru(folio))
 		return;
-	}
+
+	folio_get(folio);
 
 	if (disable_irq)
 		local_lock_irqsave(&cpu_fbatches.lock_irq, flags);
_

Patches currently in -mm which might be from yangge1116@126.com are

mm-swap-take-folio-refcount-after-testing-the-lru-flag.patch