diff options
| author | Lorenzo Stoakes <ljs@kernel.org> | 2026-07-10 21:17:03 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-08-04 19:19:01 -0700 |
| commit | e65f4dfac104d078862357eee5e602e1754de3f9 (patch) | |
| tree | a58bf046895f94204aaf636e519143b1b8ae3ce6 /include/linux | |
| parent | 93d23dff8eb5045a9cb54bf6202324da0c7010cb (diff) | |
mm/vma: introduce vma_assert_can_modify()
vma_assert_write_locked() and vma_assert_attached() are useful for their
own purposes, however VMA code absolutely does allow the modification of
non-write locked VMAs if they are at that point detached (i.e. unreachable
from anywhere).
It's therefore useful to be able to assert that a VMA is either
detached (modification doesn't matter) or write locked (you're explicitly
locked for modification).
Therefore introduce vma_assert_can_modify() for this purpose.
While we're here, make vma_is_attached() available generally - if
!CONFIG_PER_VMA_LOCK, then there's no sense in which a VMA is
detached (vma_mark_detached() is a noop), so have this default to true in
this case.
Also update VMA userland tests to reflect this change, correcting the
previously open-coded vma_assert_[attached,detached]() there.
Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-22-2a5aa403d977@kernel.org
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Kai Huang <kai.huang@intel.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: SJ Park <sj@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Liam R. Howlett (Oracle) <liam@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mmap_lock.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index 04b8f61ece5d..d513286d8160 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -506,6 +506,8 @@ static inline __must_check int vma_start_write_killable(struct vm_area_struct *vma) { return 0; } static inline void vma_assert_write_locked(struct vm_area_struct *vma) { mmap_assert_write_locked(vma->vm_mm); } +static inline bool vma_is_attached(struct vm_area_struct *vma) + { return true; } static inline void vma_assert_attached(struct vm_area_struct *vma) {} static inline void vma_assert_detached(struct vm_area_struct *vma) {} static inline void vma_mark_attached(struct vm_area_struct *vma) {} @@ -530,6 +532,12 @@ static inline void vma_assert_stabilised(struct vm_area_struct *vma) #endif /* CONFIG_PER_VMA_LOCK */ +static inline void vma_assert_can_modify(struct vm_area_struct *vma) +{ + if (vma_is_attached(vma)) + vma_assert_write_locked(vma); +} + static inline void mmap_write_lock(struct mm_struct *mm) { __mmap_lock_trace_start_locking(mm, true); |