On Wed, Jan 25, 2023 at 12:38:46AM -0800, Suren Baghdasaryan wrote:
vm_flags are among VMA attributes which affect decisions like VMA merging and splitting. Therefore all vm_flags modifications are performed after taking exclusive mmap_lock to prevent vm_flags updates racing with such operations. Introduce modifier functions for vm_flags to be used whenever flags are updated. This way we can better check and control correct locking behavior during these updates.
Signed-off-by: Suren Baghdasaryan surenb@google.com
include/linux/mm.h | 37 +++++++++++++++++++++++++++++++++++++ include/linux/mm_types.h | 8 +++++++- 2 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index c2f62bdce134..b71f2809caac 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -627,6 +627,43 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm) INIT_LIST_HEAD(&vma->anon_vma_chain); }
+/* Use when VMA is not part of the VMA tree and needs no locking */ +static inline void init_vm_flags(struct vm_area_struct *vma,
unsigned long flags)
I'd suggest to make it vm_flags_init() etc. Except that
Acked-by: Mike Rapoport (IBM) rppt@kernel.org
+{
- vma->vm_flags = flags;
+}
+/* Use when VMA is part of the VMA tree and modifications need coordination */ +static inline void reset_vm_flags(struct vm_area_struct *vma,
unsigned long flags)+{
- mmap_assert_write_locked(vma->vm_mm);
- init_vm_flags(vma, flags);
+}
+static inline void set_vm_flags(struct vm_area_struct *vma,
unsigned long flags)+{
- mmap_assert_write_locked(vma->vm_mm);
- vma->vm_flags |= flags;
+}
+static inline void clear_vm_flags(struct vm_area_struct *vma,
unsigned long flags)+{
- mmap_assert_write_locked(vma->vm_mm);
- vma->vm_flags &= ~flags;
+}
+static inline void mod_vm_flags(struct vm_area_struct *vma,
unsigned long set, unsigned long clear)+{
- mmap_assert_write_locked(vma->vm_mm);
- vma->vm_flags |= set;
- vma->vm_flags &= ~clear;
+}
static inline void vma_set_anonymous(struct vm_area_struct *vma) { vma->vm_ops = NULL; diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 2d6d790d9bed..6c7c70bf50dd 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -491,7 +491,13 @@ struct vm_area_struct { * See vmf_insert_mixed_prot() for discussion. */ pgprot_t vm_page_prot;
- unsigned long vm_flags; /* Flags, see mm.h. */
/*
* Flags, see mm.h.* WARNING! Do not modify directly.* Use {init|reset|set|clear|mod}_vm_flags() functions instead.*/unsigned long vm_flags;
/*
- For areas with an address space and backing store,
-- 2.39.1