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Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Mike Rapoport , Suren Baghdasaryan , Kees Cook , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vineet Gupta , Russell King , Catalin Marinas , Will Deacon , Brian Cain , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Dinh Nguyen , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Richard Weinberger , Anton Ivanov , Johannes Berg , Alexander Viro , Christian Brauner , Jan Kara , Xu Xin , Chengming Zhou , Michal Hocko , Paul Moore , Stephen Smalley , Ondrej Mosnacek , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, linux-fsdevel@vger.kernel.org, selinux@vger.kernel.org Subject: [PATCH 05/20] mm/vma: use new VMA flags for sticky flags logic Date: Thu, 12 Mar 2026 19:16:03 +0000 Message-ID: <1c1de926ad498edf8fa4fe9bad3783e922b62aab.1773342102.git.ljs@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 6B4771C000E X-Stat-Signature: 6icr1oj69nwassk8rujey9gqk8cbwkfx X-HE-Tag: 1773343007-620987 X-HE-Meta: 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 NCsNLynu bsbQTuDIACWgKpQKXcQZNiBFy7PKNPRKJy0szslkDdYG8u3b7Z+Eau1HOoaVsqkX92XUkSpGTed4TkWtACb1JhGBap7Gr0z0Een5qy4dKzIlnczKPQIggjgIy8HHEqs44lfZpl31Mi68idjm520dHRw/W6L4kQm8gVBSLhHa9w8lENJRCN+K5WOVN5JTW6vjhPJEq+hlA6yJAgxgjJCJGlSYgaEiO5Oo+MVw8L8CFffEf8NjksWYq7++MQ8VAcVEMY7/+5qMY8qhORyC/BoiZTWHi7Rnc0WTw6wa3MG9jsuifqBhR3bvpfEM2WA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Use the new vma_flags_t flags implementation to perform the logic around sticky flags and what flags are ignored on VMA merge. We make use of the new vma_flags_empty(), vma_flags_diff_pair(), and vma_flags_and_mask() functionality. Note that we cannot rely on VM_NONE convenience any longer, so have to explicitly check for cases where VMA flags would not be specified. Also update the VMA tests accordingly. Signed-off-by: Lorenzo Stoakes (Oracle) --- include/linux/mm.h | 32 +++++++++++--------- mm/vma.c | 47 ++++++++++++++++++++++-------- tools/testing/vma/include/custom.h | 5 ---- tools/testing/vma/include/dup.h | 9 ++++-- 4 files changed, 61 insertions(+), 32 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 3d82e53875fa..7acd2f0237eb 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -542,6 +542,7 @@ enum { /* VMA basic access permission flags */ #define VM_ACCESS_FLAGS (VM_READ | VM_WRITE | VM_EXEC) +#define VMA_ACCESS_FLAGS mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, VMA_EXEC_BIT) /* * Special vmas that are non-mergable, non-mlock()able. @@ -587,27 +588,32 @@ enum { * possesses it but the other does not, the merged VMA should nonetheless have * applied to it: * - * VM_SOFTDIRTY - if a VMA is marked soft-dirty, that is has not had its - * references cleared via /proc/$pid/clear_refs, any merged VMA - * should be considered soft-dirty also as it operates at a VMA - * granularity. + * VMA_SOFTDIRTY_BIT - if a VMA is marked soft-dirty, that is has not had its + * references cleared via /proc/$pid/clear_refs, any + * merged VMA should be considered soft-dirty also as it + * operates at a VMA granularity. * - * VM_MAYBE_GUARD - If a VMA may have guard regions in place it implies that - * mapped page tables may contain metadata not described by the - * VMA and thus any merged VMA may also contain this metadata, - * and thus we must make this flag sticky. + * VMA_MAYBE_GUARD_BIT - If a VMA may have guard regions in place it implies + * that mapped page tables may contain metadata not + * described by the VMA and thus any merged VMA may also + * contain this metadata, and thus we must make this flag + * sticky. */ -#define VM_STICKY (VM_SOFTDIRTY | VM_MAYBE_GUARD) +#ifdef CONFIG_MEM_SOFT_DIRTY +#define VMA_STICKY_FLAGS mk_vma_flags(VMA_SOFTDIRTY_BIT, VMA_MAYBE_GUARD_BIT) +#else +#define VMA_STICKY_FLAGS mk_vma_flags(VMA_MAYBE_GUARD_BIT) +#endif /* * VMA flags we ignore for the purposes of merge, i.e. one VMA possessing one * of these flags and the other not does not preclude a merge. * - * VM_STICKY - When merging VMAs, VMA flags must match, unless they are - * 'sticky'. If any sticky flags exist in either VMA, we simply - * set all of them on the merged VMA. + * VMA_STICKY_FLAGS - When merging VMAs, VMA flags must match, unless they + * are 'sticky'. If any sticky flags exist in either VMA, + * we simply set all of them on the merged VMA. */ -#define VM_IGNORE_MERGE VM_STICKY +#define VMA_IGNORE_MERGE_FLAGS VMA_STICKY_FLAGS /* * Flags which should result in page tables being copied on fork. These are diff --git a/mm/vma.c b/mm/vma.c index be64f781a3aa..6168bdc772de 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -86,10 +86,15 @@ static bool vma_is_fork_child(struct vm_area_struct *vma) static inline bool is_mergeable_vma(struct vma_merge_struct *vmg, bool merge_next) { struct vm_area_struct *vma = merge_next ? vmg->next : vmg->prev; + vma_flags_t diff; if (!mpol_equal(vmg->policy, vma_policy(vma))) return false; - if ((vma->vm_flags ^ vmg->vm_flags) & ~VM_IGNORE_MERGE) + + diff = vma_flags_diff_pair(&vma->flags, &vmg->vma_flags); + vma_flags_clear_mask(&diff, VMA_IGNORE_MERGE_FLAGS); + + if (!vma_flags_empty(&diff)) return false; if (vma->vm_file != vmg->file) return false; @@ -805,7 +810,8 @@ static bool can_merge_remove_vma(struct vm_area_struct *vma) static __must_check struct vm_area_struct *vma_merge_existing_range( struct vma_merge_struct *vmg) { - vm_flags_t sticky_flags = vmg->vm_flags & VM_STICKY; + vma_flags_t sticky_flags = vma_flags_and_mask(&vmg->vma_flags, + VMA_STICKY_FLAGS); struct vm_area_struct *middle = vmg->middle; struct vm_area_struct *prev = vmg->prev; struct vm_area_struct *next; @@ -898,15 +904,21 @@ static __must_check struct vm_area_struct *vma_merge_existing_range( vma_start_write(middle); if (merge_right) { + const vma_flags_t next_sticky = + vma_flags_and_mask(&next->flags, VMA_STICKY_FLAGS); + vma_start_write(next); vmg->target = next; - sticky_flags |= (next->vm_flags & VM_STICKY); + vma_flags_set_mask(&sticky_flags, next_sticky); } if (merge_left) { + const vma_flags_t prev_sticky = + vma_flags_and_mask(&prev->flags, VMA_STICKY_FLAGS); + vma_start_write(prev); vmg->target = prev; - sticky_flags |= (prev->vm_flags & VM_STICKY); + vma_flags_set_mask(&sticky_flags, prev_sticky); } if (merge_both) { @@ -976,7 +988,7 @@ static __must_check struct vm_area_struct *vma_merge_existing_range( if (err || commit_merge(vmg)) goto abort; - vm_flags_set(vmg->target, sticky_flags); + vma_set_flags_mask(vmg->target, sticky_flags); khugepaged_enter_vma(vmg->target, vmg->vm_flags); vmg->state = VMA_MERGE_SUCCESS; return vmg->target; @@ -1154,7 +1166,10 @@ int vma_expand(struct vma_merge_struct *vmg) struct vm_area_struct *target = vmg->target; struct vm_area_struct *next = vmg->next; bool remove_next = false; - vm_flags_t sticky_flags; + vma_flags_t sticky_flags = + vma_flags_and_mask(&vmg->vma_flags, VMA_STICKY_FLAGS); + const vma_flags_t target_sticky = + vma_flags_and_mask(&target->flags, VMA_STICKY_FLAGS); int ret = 0; mmap_assert_write_locked(vmg->mm); @@ -1174,10 +1189,13 @@ int vma_expand(struct vma_merge_struct *vmg) VM_WARN_ON_VMG(target->vm_start < vmg->start || target->vm_end > vmg->end, vmg); - sticky_flags = vmg->vm_flags & VM_STICKY; - sticky_flags |= target->vm_flags & VM_STICKY; - if (remove_next) - sticky_flags |= next->vm_flags & VM_STICKY; + vma_flags_set_mask(&sticky_flags, target_sticky); + if (remove_next) { + const vma_flags_t next_sticky = + vma_flags_and_mask(&next->flags, VMA_STICKY_FLAGS); + + vma_flags_set_mask(&sticky_flags, next_sticky); + } /* * If we are removing the next VMA or copying from a VMA @@ -1200,7 +1218,7 @@ int vma_expand(struct vma_merge_struct *vmg) if (commit_merge(vmg)) goto nomem; - vm_flags_set(target, sticky_flags); + vma_set_flags_mask(target, sticky_flags); return 0; nomem: @@ -1950,10 +1968,15 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, */ static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) { + vma_flags_t diff = vma_flags_diff_pair(&a->flags, &b->flags); + + vma_flags_clear_mask(&diff, VMA_ACCESS_FLAGS); + vma_flags_clear_mask(&diff, VMA_IGNORE_MERGE_FLAGS); + return a->vm_end == b->vm_start && mpol_equal(vma_policy(a), vma_policy(b)) && a->vm_file == b->vm_file && - !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_IGNORE_MERGE)) && + vma_flags_empty(&diff) && b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); } diff --git a/tools/testing/vma/include/custom.h b/tools/testing/vma/include/custom.h index da84f54cf977..6f43bbc494e2 100644 --- a/tools/testing/vma/include/custom.h +++ b/tools/testing/vma/include/custom.h @@ -132,8 +132,3 @@ static __always_inline bool vma_flags_same_mask(vma_flags_t *flags, vma_flags_same_mask(flags, mk_vma_flags(__VA_ARGS__)) #define VMA_SPECIAL_FLAGS mk_vma_flags(VMA_IO_BIT, VMA_DONTEXPAND_BIT, \ VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT) -#ifdef CONFIG_MEM_SOFT_DIRTY -#define VMA_STICKY_FLAGS mk_vma_flags(VMA_SOFTDIRTY_BIT, VMA_MAYBE_GUARD_BIT) -#else -#define VMA_STICKY_FLAGS mk_vma_flags(VMA_MAYBE_GUARD_BIT) -#endif diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h index 005cef50704f..069910f63b84 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -338,6 +338,7 @@ enum { /* VMA basic access permission flags */ #define VM_ACCESS_FLAGS (VM_READ | VM_WRITE | VM_EXEC) +#define VMA_ACCESS_FLAGS mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, VMA_EXEC_BIT) /* * Special vmas that are non-mergable, non-mlock()able. @@ -363,9 +364,13 @@ enum { #define CAP_IPC_LOCK 14 -#define VM_STICKY (VM_SOFTDIRTY | VM_MAYBE_GUARD) +#ifdef CONFIG_MEM_SOFT_DIRTY +#define VMA_STICKY_FLAGS mk_vma_flags(VMA_SOFTDIRTY_BIT, VMA_MAYBE_GUARD_BIT) +#else +#define VMA_STICKY_FLAGS mk_vma_flags(VMA_MAYBE_GUARD_BIT) +#endif -#define VM_IGNORE_MERGE VM_STICKY +#define VMA_IGNORE_MERGE_FLAGS VMA_STICKY_FLAGS #define VM_COPY_ON_FORK (VM_PFNMAP | VM_MIXEDMAP | VM_UFFD_WP | VM_MAYBE_GUARD) -- 2.53.0