From 71fdcf9283536370235b5f0a0e3a79b715bdb078 Mon Sep 17 00:00:00 2001 From: "Lorenzo Stoakes (Oracle)" Date: Fri, 20 Mar 2026 19:38:42 +0000 Subject: [PATCH] mm: simplify VMA flag tests of excluded flags We have implemented flag mask comparisons of the form: if ((vm_flags & (VM_FOO|VM_BAR|VM_BAZ) == VM_FOO) { ... } Like-for-like in the code using a bitwise-and mask via vma_flags_and() and using vma_flags_same() to ensure the final result equals only the required flag value. This is fine but confusing, make things clearer by instead explicitly excluding undesired flags and including the desired one via tests of the form: if (vma_flags_test(&flags, VMA_FOO_BIT) && !vma_flags_test_any(&flags, VMA_BAR_BIT, VMA_BAZ_BIT)) { ... } Which makes it easier to understand what is going on. No functional change intended. Link: https://lkml.kernel.org/r/d395c5dd837a9864f5efcec42175910afbe3ce73.1774034900.git.ljs@kernel.org Signed-off-by: Lorenzo Stoakes (Oracle) Suggested-by: Vlastimil Babka (SUSE) Acked-by: Vlastimil Babka (SUSE) Cc: Albert Ou Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Al Viro Cc: Anton Ivanov Cc: "Borislav Petkov (AMD)" Cc: Catalin Marinas Cc: Chengming Zhou Cc: Christian Borntraeger Cc: Christian Brauner Cc: David Hildenbrand Cc: Dinh Nguyen Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Huacai Chen Cc: Ingo Molnar Cc: Jan Kara Cc: Jann Horn Cc: Johannes Berg Cc: Kees Cook Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Ondrej Mosnacek Cc: Palmer Dabbelt Cc: Paul Moore Cc: Pedro Falcato Cc: Richard Weinberger Cc: Russell King Cc: Stephen Smalley Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Cc: Vineet Gupta Cc: WANG Xuerui Cc: Will Deacon Cc: xu xin Signed-off-by: Andrew Morton --- mm/mprotect.c | 12 ++++-------- mm/vma.c | 7 +++---- mm/vma.h | 6 ++---- 3 files changed, 9 insertions(+), 16 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 007d9a72b2f0..110d47a36d4b 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -784,14 +784,10 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major * fault on access. */ - if (vma_flags_test(&new_vma_flags, VMA_WRITE_BIT)) { - const vma_flags_t mask = - vma_flags_and(&old_vma_flags, VMA_WRITE_BIT, - VMA_SHARED_BIT, VMA_LOCKED_BIT); - - if (vma_flags_same(&mask, VMA_LOCKED_BIT)) - populate_vma_page_range(vma, start, end, NULL); - } + if (vma_flags_test(&new_vma_flags, VMA_WRITE_BIT) && + vma_flags_test(&old_vma_flags, VMA_LOCKED_BIT) && + !vma_flags_test_any(&old_vma_flags, VMA_WRITE_BIT, VMA_SHARED_BIT)) + populate_vma_page_range(vma, start, end, NULL); vm_stat_account(mm, vma_flags_to_legacy(old_vma_flags), -nrpages); newflags = vma_flags_to_legacy(new_vma_flags); diff --git a/mm/vma.c b/mm/vma.c index c335f989586f..a4b30a069153 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -2343,7 +2343,6 @@ void mm_drop_all_locks(struct mm_struct *mm) static bool accountable_mapping(struct mmap_state *map) { const struct file *file = map->file; - vma_flags_t mask; /* * hugetlb has its own accounting separate from the core VM @@ -2352,9 +2351,9 @@ static bool accountable_mapping(struct mmap_state *map) if (file && is_file_hugepages(file)) return false; - mask = vma_flags_and(&map->vma_flags, VMA_NORESERVE_BIT, VMA_SHARED_BIT, - VMA_WRITE_BIT); - return vma_flags_same(&mask, VMA_WRITE_BIT); + return vma_flags_test(&map->vma_flags, VMA_WRITE_BIT) && + !vma_flags_test_any(&map->vma_flags, VMA_NORESERVE_BIT, + VMA_SHARED_BIT); } /* diff --git a/mm/vma.h b/mm/vma.h index adc18f7dd9f1..1bfe7e47f6be 100644 --- a/mm/vma.h +++ b/mm/vma.h @@ -529,10 +529,8 @@ static inline bool is_data_mapping(vm_flags_t flags) static inline bool is_data_mapping_vma_flags(const vma_flags_t *vma_flags) { - const vma_flags_t mask = vma_flags_and(vma_flags, - VMA_WRITE_BIT, VMA_SHARED_BIT, VMA_STACK_BIT); - - return vma_flags_same(&mask, VMA_WRITE_BIT); + return vma_flags_test(vma_flags, VMA_WRITE_BIT) && + !vma_flags_test_any(vma_flags, VMA_SHARED_BIT, VMA_STACK_BIT); } static inline void vma_iter_config(struct vma_iterator *vmi,