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mm/vma: use new VMA flags for sticky flags logic

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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.

Also update the VMA tests accordingly.

Link: https://lkml.kernel.org/r/369574f06360ffa44707047e3b58eb4897345fba.1774034900.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes (Oracle) 2026-03-20 19:38:22 +00:00 committed by Andrew Morton
parent bd44d91d0c
commit 7ec1885a7e
4 changed files with 62 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
include/linux/mm.h
View File

@ -540,6 +540,7 @@ 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.
@ -585,27 +586,32 @@ 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

48
mm/vma.c
View File

@ -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 +904,22 @@ static __must_check struct vm_area_struct *vma_merge_existing_range(
vma_start_write(middle);
if (merge_right) {
vma_flags_t next_sticky;
vma_start_write(next);
vmg->target = next;
sticky_flags |= (next->vm_flags & VM_STICKY);
next_sticky = vma_flags_and_mask(&next->flags, VMA_STICKY_FLAGS);
vma_flags_set_mask(&sticky_flags, next_sticky);
}
if (merge_left) {
vma_flags_t prev_sticky;
vma_start_write(prev);
vmg->target = prev;
sticky_flags |= (prev->vm_flags & VM_STICKY);
prev_sticky = vma_flags_and_mask(&prev->flags, VMA_STICKY_FLAGS);
vma_flags_set_mask(&sticky_flags, prev_sticky);
}
if (merge_both) {
@ -976,7 +989,7 @@ 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;
@ -1154,12 +1167,16 @@ 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);
vma_flags_t target_sticky;
int ret = 0;
mmap_assert_write_locked(vmg->mm);
vma_start_write(target);
target_sticky = vma_flags_and_mask(&target->flags, VMA_STICKY_FLAGS);
if (next && target != next && vmg->end == next->vm_end)
remove_next = true;
@ -1174,10 +1191,7 @@ 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 we are removing the next VMA or copying from a VMA
@ -1194,13 +1208,18 @@ int vma_expand(struct vma_merge_struct *vmg)
return ret;
if (remove_next) {
vma_flags_t next_sticky;
vma_start_write(next);
vmg->__remove_next = true;
next_sticky = vma_flags_and_mask(&next->flags, VMA_STICKY_FLAGS);
vma_flags_set_mask(&sticky_flags, next_sticky);
}
if (commit_merge(vmg))
goto nomem;
vm_flags_set(target, sticky_flags);
vma_set_flags_mask(target, sticky_flags);
return 0;
nomem:
@ -1950,10 +1969,15 @@ 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);
}

5
tools/testing/vma/include/custom.h
View File

@ -134,8 +134,3 @@ 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

9
tools/testing/vma/include/dup.h
View File

@ -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)