Re: [PATCH 07/25] mm/fbatch: LRU_NEXT_ACTIVATE bit to optimize folio_activate()
From: Kiryl Shutsemau <kas@kernel.org>
Date: 2026-08-27 12:02:31
Also in:
linux-fsdevel, linux-mm, lkml
On Mon, Aug 24, 2026 at 07:09:34AM -0700, Hugh Dickins wrote:
quoted hunk ↗ jump to hunk
@@ -355,6 +356,8 @@ bool lru_add_del_folio(struct folio *folio) /* BUG_ON(folio_test_lru(folio)); */ if (!(folio->lru_next & BIT(LRU_NEXT_BATCHED))) return false; + if (folio->lru_next & BIT(LRU_NEXT_ACTIVATE)) + folio_set_active(folio); folio->lru.next = LIST_POISON1; /* BUG_ON(folio->lru_next & BIT(LRU_NEXT_BATCHED)); */ return true;
folio_activate()'s try_cmpxchg() can land in between two lru_next reads. Logically, it is safe but I suspect KCSAN would not be happy about it. Maybe READ_ONCE() here? Other note, page_pool (pp_magic) seems to be using bit 2, but I don't think there's a real conflict. -- Kiryl Shutsemau / Kirill A. Shutemov