From: yangge Date: Tue, 13 Aug 2024 09:52:23 +0000 (+0800) Subject: mm/swap: take folio refcount after testing the LRU flag X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=84845d2630dbd62a0b9bb0b76aa3efc95e8b0657;p=users%2Fjedix%2Flinux-maple.git mm/swap: take folio refcount after testing the LRU flag 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 Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Yu Zhao Signed-off-by: Andrew Morton --- diff --git a/mm/swap.c b/mm/swap.c index 67a246772811..6b838986d294 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -226,12 +226,10 @@ static void __folio_batch_add_and_move(struct folio_batch __percpu *fbatch, { 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);