From 9e98b6dd46f53ae02de62e4efa286c93f8610a0f Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Fri, 10 Jul 2026 21:17:12 +0100 Subject: [PATCH] mm/vma: use guard clauses in can_vma_merge_[before, after]() Rather than combining a bunch of conditionals in a single expression, simplify by inverting the mergeability requirements into guard clauses. that is - instead of checking what must be true for the conditions to be met, instead check the inverse of the requirements and return false if any are true, defaulting to true. No functional change intended. Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-31-2a5aa403d977@kernel.org Signed-off-by: Lorenzo Stoakes Reviewed-by: Pedro Falcato Reviewed-by: Gregory Price Reviewed-by: Vlastimil Babka (SUSE) Cc: Ackerley Tng Cc: David Hildenbrand (Arm) Cc: Kai Huang Cc: Marek Szyprowski Cc: SJ Park Cc: Thomas Zimmermann Cc: Liam R. Howlett (Oracle) Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/vma.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) diff --git a/mm/vma.c b/mm/vma.c index d74a8ae16bfa..12a684c36b6c 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -215,13 +215,13 @@ static void init_multi_vma_prep(struct vma_prepare *vp, */ static bool can_vma_merge_before(struct vma_merge_struct *vmg) { - if (is_mergeable_vma(vmg, /* merge_next = */ true) && - is_mergeable_anon_vma(vmg, /* merge_next = */ true)) { - if (vmg_end_pgoff(vmg) == vma_start_pgoff(vmg->next)) - return true; - } - - return false; + if (!is_mergeable_vma(vmg, /* merge_next = */ true)) + return false; + if (!is_mergeable_anon_vma(vmg, /* merge_next = */ true)) + return false; + if (vmg_end_pgoff(vmg) != vma_start_pgoff(vmg->next)) + return false; + return true; } /* @@ -235,12 +235,13 @@ static bool can_vma_merge_before(struct vma_merge_struct *vmg) */ static bool can_vma_merge_after(struct vma_merge_struct *vmg) { - if (is_mergeable_vma(vmg, /* merge_next = */ false) && - is_mergeable_anon_vma(vmg, /* merge_next = */ false)) { - if (vma_end_pgoff(vmg->prev) == vmg_start_pgoff(vmg)) - return true; - } - return false; + if (!is_mergeable_vma(vmg, /* merge_next = */ false)) + return false; + if (!is_mergeable_anon_vma(vmg, /* merge_next = */ false)) + return false; + if (vma_end_pgoff(vmg->prev) != vmg_start_pgoff(vmg)) + return false; + return true; } static void __vma_link_file(struct vm_area_struct *vma,