# \[PATCH 34/39\] mm: eliminate VMA\_SPECIAL\_FLAGS check in lru\_gen\_look\_around() - From: Lorenzo Stoakes (ARM) \ - Date: 2026-09-08 20:18:39 - List: linux-trace-kernel - Page: https://ratatoskr.run/linux-trace-kernel/2026/09/17533601 - Thread: https://ratatoskr.run/linux-mm/2026/09/17533522/t.md ```text A kernel-owned or fixed mapping is one which sets VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT or VMA_DONTEXPAND_BIT, which is precisely what VMA_SPECIAL_FLAGS tests for other than VMA_IO_BIT, which is safe to drop as only kernel-owned mappings may set it. Using these predicates rather than VMA_SPECIAL_FLAGS makes the check self-documenting and helps eliminate the confusion around 'special' flags. No functional change intended. Signed-off-by: Lorenzo Stoakes (ARM) --- mm/vmscan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 803754caf4fa..0082afbdbbdd 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4364,8 +4364,8 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr) if (spin_is_contended(pvmw->ptl)) return true; - /* exclude special VMAs containing anon pages from COW */ - if (vma->vm_flags & VM_SPECIAL) + /* exclude kernel-owned and fixed VMAs containing anon pages from COW */ + if (vma_is_kernel_owned(vma) || vma_is_fixed_mapping(vma)) return true; /* avoid taking the LRU lock under the PTL when possible */ -- 2.55.0 ```