[merged mm-stable] mm-introduce-vma-flags-bitmap-type.patch removed from -mm tree

[merged mm-stable] mm-introduce-vma-flags-bitmap-type.patch removed from -mm tree

[Andrew Morton]

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The quilt patch titled
     Subject: mm: introduce VMA flags bitmap type
has been removed from the -mm tree.  Its filename was
     mm-introduce-vma-flags-bitmap-type.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: mm: introduce VMA flags bitmap type
Date: Fri, 14 Nov 2025 13:26:11 +0000

It is useful to transition to using a bitmap for VMA flags so we can avoid
running out of flags, especially for 32-bit kernels which are constrained
to 32 flags, necessitating some features to be limited to 64-bit kernels
only.

By doing so, we remove any constraint on the number of VMA flags moving
forwards no matter the platform and can decide in future to extend beyond
64 if required.

We start by declaring an opaque types, vma_flags_t (which resembles
mm_struct flags of type mm_flags_t), setting it to precisely the same size
as vm_flags_t, and place it in union with vm_flags in the VMA declaration.

We additionally update struct vm_area_desc equivalently placing the new
opaque type in union with vm_flags.

This change therefore does not impact the size of struct vm_area_struct or
struct vm_area_desc.

In order for the change to be iterative and to avoid impacting
performance, we designate VM_xxx declared bitmap flag values as those
which must exist in the first system word of the VMA flags bitmap.

We therefore declare vma_flags_clear_all(), vma_flags_overwrite_word(),
vma_flags_overwrite_word(), vma_flags_overwrite_word_once(),
vma_flags_set_word() and vma_flags_clear_word() in order to allow us to
update the existing vm_flags_*() functions to utilise these helpers.

This is a stepping stone towards converting users to the VMA flags bitmap
and behaves precisely as before.

By doing this, we can eliminate the existing private vma->__vm_flags field
in the vma->vm_flags union and replace it with the newly introduced opaque
type vma_flags, which we call flags so we refer to the new bitmap field as
vma->flags.

We update vma_flag_[test, set]_atomic() to account for the change also.

We additionally update the VMA userland test declarations to implement the
same changes there.

Finally, we update the rust code to reference vma->vm_flags on update
rather than vma->__vm_flags which has been removed.  This is safe for now,
albeit it is implicitly performing a const cast.

Once we introduce flag helpers we can improve this more.

No functional change intended.

Link: https://lkml.kernel.org/r/195625e7d1a8ff9156cb9bb294eb128b6a4e9294.1763126447.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h               |   18 +
 include/linux/mm_types.h         |   64 +++++-
 rust/kernel/mm/virt.rs           |    2 
 tools/testing/vma/vma_internal.h |  303 ++++-------------------------
 4 files changed, 121 insertions(+), 266 deletions(-)

--- a/include/linux/mm.h~mm-introduce-vma-flags-bitmap-type
+++ a/include/linux/mm.h
@@ -910,7 +910,8 @@ static inline void vma_init(struct vm_ar
 static inline void vm_flags_init(struct vm_area_struct *vma,
 				 vm_flags_t flags)
 {
-	ACCESS_PRIVATE(vma, __vm_flags) = flags;
+	vma_flags_clear_all(&vma->flags);
+	vma_flags_overwrite_word(&vma->flags, flags);
 }
 
 /*
@@ -929,21 +930,26 @@ static inline void vm_flags_reset_once(s
 				       vm_flags_t flags)
 {
 	vma_assert_write_locked(vma);
-	WRITE_ONCE(ACCESS_PRIVATE(vma, __vm_flags), flags);
+	/*
+	 * The user should only be interested in avoiding reordering of
+	 * assignment to the first word.
+	 */
+	vma_flags_clear_all(&vma->flags);
+	vma_flags_overwrite_word_once(&vma->flags, flags);
 }
 
 static inline void vm_flags_set(struct vm_area_struct *vma,
 				vm_flags_t flags)
 {
 	vma_start_write(vma);
-	ACCESS_PRIVATE(vma, __vm_flags) |= flags;
+	vma_flags_set_word(&vma->flags, flags);
 }
 
 static inline void vm_flags_clear(struct vm_area_struct *vma,
 				  vm_flags_t flags)
 {
 	vma_start_write(vma);
-	ACCESS_PRIVATE(vma, __vm_flags) &= ~flags;
+	vma_flags_clear_word(&vma->flags, flags);
 }
 
 /*
@@ -986,12 +992,14 @@ static inline bool __vma_flag_atomic_val
 static inline void vma_flag_set_atomic(struct vm_area_struct *vma,
 				       vma_flag_t bit)
 {
+	unsigned long *bitmap = ACCESS_PRIVATE(&vma->flags, __vma_flags);
+
 	/* mmap read lock/VMA read lock must be held. */
 	if (!rwsem_is_locked(&vma->vm_mm->mmap_lock))
 		vma_assert_locked(vma);
 
 	if (__vma_flag_atomic_valid(vma, bit))
-		set_bit((__force int)bit, &ACCESS_PRIVATE(vma, __vm_flags));
+		set_bit((__force int)bit, bitmap);
 }
 
 /*
--- a/include/linux/mm_types.h~mm-introduce-vma-flags-bitmap-type
+++ a/include/linux/mm_types.h
@@ -824,6 +824,15 @@ struct mmap_action {
 };
 
 /*
+ * Opaque type representing current VMA (vm_area_struct) flag state. Must be
+ * accessed via vma_flags_xxx() helper functions.
+ */
+#define NUM_VMA_FLAG_BITS BITS_PER_LONG
+typedef struct {
+	DECLARE_BITMAP(__vma_flags, NUM_VMA_FLAG_BITS);
+} __private vma_flags_t;
+
+/*
  * Describes a VMA that is about to be mmap()'ed. Drivers may choose to
  * manipulate mutable fields which will cause those fields to be updated in the
  * resultant VMA.
@@ -840,7 +849,10 @@ struct vm_area_desc {
 	/* Mutable fields. Populated with initial state. */
 	pgoff_t pgoff;
 	struct file *vm_file;
-	vm_flags_t vm_flags;
+	union {
+		vm_flags_t vm_flags;
+		vma_flags_t vma_flags;
+	};
 	pgprot_t page_prot;
 
 	/* Write-only fields. */
@@ -885,10 +897,12 @@ struct vm_area_struct {
 	/*
 	 * Flags, see mm.h.
 	 * To modify use vm_flags_{init|reset|set|clear|mod} functions.
+	 * Preferably, use vma_flags_xxx() functions.
 	 */
 	union {
+		/* Temporary while VMA flags are being converted. */
 		const vm_flags_t vm_flags;
-		vm_flags_t __private __vm_flags;
+		vma_flags_t flags;
 	};
 
 #ifdef CONFIG_PER_VMA_LOCK
@@ -969,6 +983,52 @@ struct vm_area_struct {
 #endif
 } __randomize_layout;
 
+/* Clears all bits in the VMA flags bitmap, non-atomically. */
+static inline void vma_flags_clear_all(vma_flags_t *flags)
+{
+	bitmap_zero(ACCESS_PRIVATE(flags, __vma_flags), NUM_VMA_FLAG_BITS);
+}
+
+/*
+ * Copy value to the first system word of VMA flags, non-atomically.
+ *
+ * IMPORTANT: This does not overwrite bytes past the first system word. The
+ * caller must account for this.
+ */
+static inline void vma_flags_overwrite_word(vma_flags_t *flags, unsigned long value)
+{
+	*ACCESS_PRIVATE(flags, __vma_flags) = value;
+}
+
+/*
+ * Copy value to the first system word of VMA flags ONCE, non-atomically.
+ *
+ * IMPORTANT: This does not overwrite bytes past the first system word. The
+ * caller must account for this.
+ */
+static inline void vma_flags_overwrite_word_once(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	WRITE_ONCE(*bitmap, value);
+}
+
+/* Update the first system word of VMA flags setting bits, non-atomically. */
+static inline void vma_flags_set_word(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	*bitmap |= value;
+}
+
+/* Update the first system word of VMA flags clearing bits, non-atomically. */
+static inline void vma_flags_clear_word(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	*bitmap &= ~value;
+}
+
 #ifdef CONFIG_NUMA
 #define vma_policy(vma) ((vma)->vm_policy)
 #else
--- a/rust/kernel/mm/virt.rs~mm-introduce-vma-flags-bitmap-type
+++ a/rust/kernel/mm/virt.rs
@@ -250,7 +250,7 @@ impl VmaNew {
         // SAFETY: This is not a data race: the vma is undergoing initial setup, so it's not yet
         // shared. Additionally, `VmaNew` is `!Sync`, so it cannot be used to write in parallel.
         // The caller promises that this does not set the flags to an invalid value.
-        unsafe { (*self.as_ptr()).__bindgen_anon_2.__vm_flags = flags };
+        unsafe { (*self.as_ptr()).__bindgen_anon_2.vm_flags = flags };
     }
 
     /// Set the `VM_MIXEDMAP` flag on this vma.
--- a/tools/testing/vma/vma_internal.h~mm-introduce-vma-flags-bitmap-type
+++ a/tools/testing/vma/vma_internal.h
@@ -46,271 +46,43 @@ extern unsigned long dac_mmap_min_addr;
 
 #define MMF_HAS_MDWE	28
 
-/*
- * vm_flags in vm_area_struct, see mm_types.h.
- * When changing, update also include/trace/events/mmflags.h
- */
-
 #define VM_NONE		0x00000000
-
-/**
- * typedef vma_flag_t - specifies an individual VMA flag by bit number.
- *
- * This value is made type safe by sparse to avoid passing invalid flag values
- * around.
- */
-typedef int __bitwise vma_flag_t;
-
-#define DECLARE_VMA_BIT(name, bitnum) \
-	VMA_ ## name ## _BIT = ((__force vma_flag_t)bitnum)
-#define DECLARE_VMA_BIT_ALIAS(name, aliased) \
-	VMA_ ## name ## _BIT = VMA_ ## aliased ## _BIT
-enum {
-	DECLARE_VMA_BIT(READ, 0),
-	DECLARE_VMA_BIT(WRITE, 1),
-	DECLARE_VMA_BIT(EXEC, 2),
-	DECLARE_VMA_BIT(SHARED, 3),
-	/* mprotect() hardcodes VM_MAYREAD >> 4 == VM_READ, and so for r/w/x bits. */
-	DECLARE_VMA_BIT(MAYREAD, 4),	/* limits for mprotect() etc. */
-	DECLARE_VMA_BIT(MAYWRITE, 5),
-	DECLARE_VMA_BIT(MAYEXEC, 6),
-	DECLARE_VMA_BIT(MAYSHARE, 7),
-	DECLARE_VMA_BIT(GROWSDOWN, 8),	/* general info on the segment */
-#ifdef CONFIG_MMU
-	DECLARE_VMA_BIT(UFFD_MISSING, 9),/* missing pages tracking */
-#else
-	/* nommu: R/O MAP_PRIVATE mapping that might overlay a file mapping */
-	DECLARE_VMA_BIT(MAYOVERLAY, 9),
-#endif /* CONFIG_MMU */
-	/* Page-ranges managed without "struct page", just pure PFN */
-	DECLARE_VMA_BIT(PFNMAP, 10),
-	DECLARE_VMA_BIT(MAYBE_GUARD, 11),
-	DECLARE_VMA_BIT(UFFD_WP, 12),	/* wrprotect pages tracking */
-	DECLARE_VMA_BIT(LOCKED, 13),
-	DECLARE_VMA_BIT(IO, 14),	/* Memory mapped I/O or similar */
-	DECLARE_VMA_BIT(SEQ_READ, 15),	/* App will access data sequentially */
-	DECLARE_VMA_BIT(RAND_READ, 16),	/* App will not benefit from clustered reads */
-	DECLARE_VMA_BIT(DONTCOPY, 17),	/* Do not copy this vma on fork */
-	DECLARE_VMA_BIT(DONTEXPAND, 18),/* Cannot expand with mremap() */
-	DECLARE_VMA_BIT(LOCKONFAULT, 19),/* Lock pages covered when faulted in */
-	DECLARE_VMA_BIT(ACCOUNT, 20),	/* Is a VM accounted object */
-	DECLARE_VMA_BIT(NORESERVE, 21),	/* should the VM suppress accounting */
-	DECLARE_VMA_BIT(HUGETLB, 22),	/* Huge TLB Page VM */
-	DECLARE_VMA_BIT(SYNC, 23),	/* Synchronous page faults */
-	DECLARE_VMA_BIT(ARCH_1, 24),	/* Architecture-specific flag */
-	DECLARE_VMA_BIT(WIPEONFORK, 25),/* Wipe VMA contents in child. */
-	DECLARE_VMA_BIT(DONTDUMP, 26),	/* Do not include in the core dump */
-	DECLARE_VMA_BIT(SOFTDIRTY, 27),	/* NOT soft dirty clean area */
-	DECLARE_VMA_BIT(MIXEDMAP, 28),	/* Can contain struct page and pure PFN pages */
-	DECLARE_VMA_BIT(HUGEPAGE, 29),	/* MADV_HUGEPAGE marked this vma */
-	DECLARE_VMA_BIT(NOHUGEPAGE, 30),/* MADV_NOHUGEPAGE marked this vma */
-	DECLARE_VMA_BIT(MERGEABLE, 31),	/* KSM may merge identical pages */
-	/* These bits are reused, we define specific uses below. */
-	DECLARE_VMA_BIT(HIGH_ARCH_0, 32),
-	DECLARE_VMA_BIT(HIGH_ARCH_1, 33),
-	DECLARE_VMA_BIT(HIGH_ARCH_2, 34),
-	DECLARE_VMA_BIT(HIGH_ARCH_3, 35),
-	DECLARE_VMA_BIT(HIGH_ARCH_4, 36),
-	DECLARE_VMA_BIT(HIGH_ARCH_5, 37),
-	DECLARE_VMA_BIT(HIGH_ARCH_6, 38),
-	/*
-	 * This flag is used to connect VFIO to arch specific KVM code. It
-	 * indicates that the memory under this VMA is safe for use with any
-	 * non-cachable memory type inside KVM. Some VFIO devices, on some
-	 * platforms, are thought to be unsafe and can cause machine crashes
-	 * if KVM does not lock down the memory type.
-	 */
-	DECLARE_VMA_BIT(ALLOW_ANY_UNCACHED, 39),
-#ifdef CONFIG_PPC32
-	DECLARE_VMA_BIT_ALIAS(DROPPABLE, ARCH_1),
-#else
-	DECLARE_VMA_BIT(DROPPABLE, 40),
-#endif
-	DECLARE_VMA_BIT(UFFD_MINOR, 41),
-	DECLARE_VMA_BIT(SEALED, 42),
-	/* Flags that reuse flags above. */
-	DECLARE_VMA_BIT_ALIAS(PKEY_BIT0, HIGH_ARCH_0),
-	DECLARE_VMA_BIT_ALIAS(PKEY_BIT1, HIGH_ARCH_1),
-	DECLARE_VMA_BIT_ALIAS(PKEY_BIT2, HIGH_ARCH_2),
-	DECLARE_VMA_BIT_ALIAS(PKEY_BIT3, HIGH_ARCH_3),
-	DECLARE_VMA_BIT_ALIAS(PKEY_BIT4, HIGH_ARCH_4),
-#if defined(CONFIG_X86_USER_SHADOW_STACK)
-	/*
-	 * VM_SHADOW_STACK should not be set with VM_SHARED because of lack of
-	 * support core mm.
-	 *
-	 * These VMAs will get a single end guard page. This helps userspace
-	 * protect itself from attacks. A single page is enough for current
-	 * shadow stack archs (x86). See the comments near alloc_shstk() in
-	 * arch/x86/kernel/shstk.c for more details on the guard size.
-	 */
-	DECLARE_VMA_BIT_ALIAS(SHADOW_STACK, HIGH_ARCH_5),
-#elif defined(CONFIG_ARM64_GCS)
-	/*
-	 * arm64's Guarded Control Stack implements similar functionality and
-	 * has similar constraints to shadow stacks.
-	 */
-	DECLARE_VMA_BIT_ALIAS(SHADOW_STACK, HIGH_ARCH_6),
-#endif
-	DECLARE_VMA_BIT_ALIAS(SAO, ARCH_1),		/* Strong Access Ordering (powerpc) */
-	DECLARE_VMA_BIT_ALIAS(GROWSUP, ARCH_1),		/* parisc */
-	DECLARE_VMA_BIT_ALIAS(SPARC_ADI, ARCH_1),	/* sparc64 */
-	DECLARE_VMA_BIT_ALIAS(ARM64_BTI, ARCH_1),	/* arm64 */
-	DECLARE_VMA_BIT_ALIAS(ARCH_CLEAR, ARCH_1),	/* sparc64, arm64 */
-	DECLARE_VMA_BIT_ALIAS(MAPPED_COPY, ARCH_1),	/* !CONFIG_MMU */
-	DECLARE_VMA_BIT_ALIAS(MTE, HIGH_ARCH_4),	/* arm64 */
-	DECLARE_VMA_BIT_ALIAS(MTE_ALLOWED, HIGH_ARCH_5),/* arm64 */
-#ifdef CONFIG_STACK_GROWSUP
-	DECLARE_VMA_BIT_ALIAS(STACK, GROWSUP),
-	DECLARE_VMA_BIT_ALIAS(STACK_EARLY, GROWSDOWN),
-#else
-	DECLARE_VMA_BIT_ALIAS(STACK, GROWSDOWN),
-#endif
-};
-
-#define INIT_VM_FLAG(name) BIT((__force int) VMA_ ## name ## _BIT)
-#define VM_READ		INIT_VM_FLAG(READ)
-#define VM_WRITE	INIT_VM_FLAG(WRITE)
-#define VM_EXEC		INIT_VM_FLAG(EXEC)
-#define VM_SHARED	INIT_VM_FLAG(SHARED)
-#define VM_MAYREAD	INIT_VM_FLAG(MAYREAD)
-#define VM_MAYWRITE	INIT_VM_FLAG(MAYWRITE)
-#define VM_MAYEXEC	INIT_VM_FLAG(MAYEXEC)
-#define VM_MAYSHARE	INIT_VM_FLAG(MAYSHARE)
-#define VM_GROWSDOWN	INIT_VM_FLAG(GROWSDOWN)
-#ifdef CONFIG_MMU
-#define VM_UFFD_MISSING	INIT_VM_FLAG(UFFD_MISSING)
-#else
-#define VM_UFFD_MISSING	VM_NONE
-#endif
-#define VM_PFNMAP	INIT_VM_FLAG(PFNMAP)
-#define VM_MAYBE_GUARD	INIT_VM_FLAG(MAYBE_GUARD)
-#define VM_UFFD_WP	INIT_VM_FLAG(UFFD_WP)
-#define VM_LOCKED	INIT_VM_FLAG(LOCKED)
-#define VM_IO		INIT_VM_FLAG(IO)
-#define VM_SEQ_READ	INIT_VM_FLAG(SEQ_READ)
-#define VM_RAND_READ	INIT_VM_FLAG(RAND_READ)
-#define VM_DONTCOPY	INIT_VM_FLAG(DONTCOPY)
-#define VM_DONTEXPAND	INIT_VM_FLAG(DONTEXPAND)
-#define VM_LOCKONFAULT	INIT_VM_FLAG(LOCKONFAULT)
-#define VM_ACCOUNT	INIT_VM_FLAG(ACCOUNT)
-#define VM_NORESERVE	INIT_VM_FLAG(NORESERVE)
-#define VM_HUGETLB	INIT_VM_FLAG(HUGETLB)
-#define VM_SYNC		INIT_VM_FLAG(SYNC)
-#define VM_ARCH_1	INIT_VM_FLAG(ARCH_1)
-#define VM_WIPEONFORK	INIT_VM_FLAG(WIPEONFORK)
-#define VM_DONTDUMP	INIT_VM_FLAG(DONTDUMP)
-#ifdef CONFIG_MEM_SOFT_DIRTY
-#define VM_SOFTDIRTY	INIT_VM_FLAG(SOFTDIRTY)
-#else
-#define VM_SOFTDIRTY	VM_NONE
-#endif
-#define VM_MIXEDMAP	INIT_VM_FLAG(MIXEDMAP)
-#define VM_HUGEPAGE	INIT_VM_FLAG(HUGEPAGE)
-#define VM_NOHUGEPAGE	INIT_VM_FLAG(NOHUGEPAGE)
-#define VM_MERGEABLE	INIT_VM_FLAG(MERGEABLE)
-#define VM_STACK	INIT_VM_FLAG(STACK)
-#ifdef CONFIG_STACK_GROWS_UP
-#define VM_STACK_EARLY	INIT_VM_FLAG(STACK_EARLY)
-#else
-#define VM_STACK_EARLY	VM_NONE
-#endif
-#ifdef CONFIG_ARCH_HAS_PKEYS
-#define VM_PKEY_SHIFT ((__force int)VMA_HIGH_ARCH_0_BIT)
-/* Despite the naming, these are FLAGS not bits. */
-#define VM_PKEY_BIT0 INIT_VM_FLAG(PKEY_BIT0)
-#define VM_PKEY_BIT1 INIT_VM_FLAG(PKEY_BIT1)
-#define VM_PKEY_BIT2 INIT_VM_FLAG(PKEY_BIT2)
-#if CONFIG_ARCH_PKEY_BITS > 3
-#define VM_PKEY_BIT3 INIT_VM_FLAG(PKEY_BIT3)
-#else
-#define VM_PKEY_BIT3  VM_NONE
-#endif /* CONFIG_ARCH_PKEY_BITS > 3 */
-#if CONFIG_ARCH_PKEY_BITS > 4
-#define VM_PKEY_BIT4 INIT_VM_FLAG(PKEY_BIT4)
-#else
-#define VM_PKEY_BIT4  VM_NONE
-#endif /* CONFIG_ARCH_PKEY_BITS > 4 */
-#endif /* CONFIG_ARCH_HAS_PKEYS */
-#if defined(CONFIG_X86_USER_SHADOW_STACK) || defined(CONFIG_ARM64_GCS)
-#define VM_SHADOW_STACK	INIT_VM_FLAG(SHADOW_STACK)
-#else
+#define VM_READ		0x00000001
+#define VM_WRITE	0x00000002
+#define VM_EXEC		0x00000004
+#define VM_SHARED	0x00000008
+#define VM_MAYREAD	0x00000010
+#define VM_MAYWRITE	0x00000020
+#define VM_MAYEXEC	0x00000040
+#define VM_GROWSDOWN	0x00000100
+#define VM_PFNMAP	0x00000400
+#define VM_MAYBE_GUARD	0x00000800
+#define VM_LOCKED	0x00002000
+#define VM_IO           0x00004000
+#define VM_SEQ_READ	0x00008000	/* App will access data sequentially */
+#define VM_RAND_READ	0x00010000	/* App will not benefit from clustered reads */
+#define VM_DONTEXPAND	0x00040000
+#define VM_LOCKONFAULT	0x00080000
+#define VM_ACCOUNT	0x00100000
+#define VM_NORESERVE	0x00200000
+#define VM_MIXEDMAP	0x10000000
+#define VM_STACK	VM_GROWSDOWN
 #define VM_SHADOW_STACK	VM_NONE
-#endif
-#if defined(CONFIG_PPC64)
-#define VM_SAO		INIT_VM_FLAG(SAO)
-#elif defined(CONFIG_PARISC)
-#define VM_GROWSUP	INIT_VM_FLAG(GROWSUP)
-#elif defined(CONFIG_SPARC64)
-#define VM_SPARC_ADI	INIT_VM_FLAG(SPARC_ADI)
-#define VM_ARCH_CLEAR	INIT_VM_FLAG(ARCH_CLEAR)
-#elif defined(CONFIG_ARM64)
-#define VM_ARM64_BTI	INIT_VM_FLAG(ARM64_BTI)
-#define VM_ARCH_CLEAR	INIT_VM_FLAG(ARCH_CLEAR)
-#elif !defined(CONFIG_MMU)
-#define VM_MAPPED_COPY	INIT_VM_FLAG(MAPPED_COPY)
-#endif
-#ifndef VM_GROWSUP
+#define VM_SOFTDIRTY	0
+#define VM_ARCH_1	0x01000000	/* Architecture-specific flag */
 #define VM_GROWSUP	VM_NONE
-#endif
-#ifdef CONFIG_ARM64_MTE
-#define VM_MTE		INIT_VM_FLAG(MTE)
-#define VM_MTE_ALLOWED	INIT_VM_FLAG(MTE_ALLOWED)
-#else
-#define VM_MTE		VM_NONE
-#define VM_MTE_ALLOWED	VM_NONE
-#endif
-#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
-#define VM_UFFD_MINOR	INIT_VM_FLAG(UFFD_MINOR)
-#else
-#define VM_UFFD_MINOR	VM_NONE
-#endif
-#ifdef CONFIG_64BIT
-#define VM_ALLOW_ANY_UNCACHED	INIT_VM_FLAG(ALLOW_ANY_UNCACHED)
-#define VM_SEALED		INIT_VM_FLAG(SEALED)
-#else
-#define VM_ALLOW_ANY_UNCACHED	VM_NONE
-#define VM_SEALED		VM_NONE
-#endif
-#if defined(CONFIG_64BIT) || defined(CONFIG_PPC32)
-#define VM_DROPPABLE		INIT_VM_FLAG(DROPPABLE)
-#else
-#define VM_DROPPABLE		VM_NONE
-#endif
-
-/* Bits set in the VMA until the stack is in its final location */
-#define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEQ_READ | VM_STACK_EARLY)
-
-#define TASK_EXEC ((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0)
-
-/* Common data flag combinations */
-#define VM_DATA_FLAGS_TSK_EXEC	(VM_READ | VM_WRITE | TASK_EXEC | \
-				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
-#define VM_DATA_FLAGS_NON_EXEC	(VM_READ | VM_WRITE | VM_MAYREAD | \
-				 VM_MAYWRITE | VM_MAYEXEC)
-#define VM_DATA_FLAGS_EXEC	(VM_READ | VM_WRITE | VM_EXEC | \
-				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
-
-#ifndef VM_DATA_DEFAULT_FLAGS		/* arch can override this */
-#define VM_DATA_DEFAULT_FLAGS  VM_DATA_FLAGS_EXEC
-#endif
 
-#ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
-#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
-#endif
-
-#define VM_STARTGAP_FLAGS (VM_GROWSDOWN | VM_SHADOW_STACK)
-
-#define VM_STACK_FLAGS	(VM_STACK | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
-
-/* VMA basic access permission flags */
 #define VM_ACCESS_FLAGS (VM_READ | VM_WRITE | VM_EXEC)
-
-/*
- * Special vmas that are non-mergable, non-mlock()able.
- */
 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP | VM_MIXEDMAP)
 
+#ifdef CONFIG_STACK_GROWSUP
+#define VM_STACK	VM_GROWSUP
+#define VM_STACK_EARLY	VM_GROWSDOWN
+#else
+#define VM_STACK	VM_GROWSDOWN
+#define VM_STACK_EARLY	0
+#endif
+
 #define DEFAULT_MAP_WINDOW	((1UL << 47) - PAGE_SIZE)
 #define TASK_SIZE_LOW		DEFAULT_MAP_WINDOW
 #define TASK_SIZE_MAX		DEFAULT_MAP_WINDOW
@@ -325,11 +97,26 @@ enum {
 #define VM_DATA_FLAGS_TSK_EXEC	(VM_READ | VM_WRITE | TASK_EXEC | \
 				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
 
+#define VM_DATA_DEFAULT_FLAGS	VM_DATA_FLAGS_TSK_EXEC
+
+#define VM_STARTGAP_FLAGS (VM_GROWSDOWN | VM_SHADOW_STACK)
+
+#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
+#define VM_STACK_FLAGS	(VM_STACK | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
+#define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEQ_READ | VM_STACK_EARLY)
+
 #define RLIMIT_STACK		3	/* max stack size */
 #define RLIMIT_MEMLOCK		8	/* max locked-in-memory address space */
 
 #define CAP_IPC_LOCK         14
 
+#ifdef CONFIG_64BIT
+#define VM_SEALED_BIT	42
+#define VM_SEALED	BIT(VM_SEALED_BIT)
+#else
+#define VM_SEALED	VM_NONE
+#endif
+
 /*
  * Flags which should be 'sticky' on merge - that is, flags which, when one VMA
  * possesses it but the other does not, the merged VMA should nonetheless have
_

Patches currently in -mm which might be from lorenzo.stoakes@oracle.com are

mm-correctly-handle-uffd-pte-markers.patch
mm-introduce-leaf-entry-type-and-use-to-simplify-leaf-entry-logic.patch
mm-avoid-unnecessary-uses-of-is_swap_pte.patch
mm-eliminate-is_swap_pte-when-softleaf_from_pte-suffices.patch
mm-use-leaf-entries-in-debug-pgtable-remove-is_swap_pte.patch
fs-proc-task_mmu-refactor-pagemap_pmd_range.patch
mm-avoid-unnecessary-use-of-is_swap_pmd.patch
mm-huge_memory-refactor-copy_huge_pmd-non-present-logic.patch
mm-huge_memory-refactor-change_huge_pmd-non-present-logic.patch
mm-replace-pmd_to_swp_entry-with-softleaf_from_pmd.patch
mm-introduce-pmd_is_huge-and-use-where-appropriate.patch
mm-remove-remaining-is_swap_pmd-users-and-is_swap_pmd.patch
mm-remove-non_swap_entry-and-use-softleaf-helpers-instead.patch
mm-remove-is_hugetlb_entry_.patch
mm-eliminate-further-swapops-predicates.patch
mm-replace-remaining-pte_to_swp_entry-with-softleaf_from_pte.patch

[merged mm-stable] mm-introduce-vma-flags-bitmap-type.patch removed from -mm tree

[Andrew Morton]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 16857 bytes --]


The quilt patch titled
     Subject: mm: introduce VMA flags bitmap type
has been removed from the -mm tree.  Its filename was
     mm-introduce-vma-flags-bitmap-type.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: mm: introduce VMA flags bitmap type
Date: Tue, 25 Nov 2025 10:01:02 +0000

It is useful to transition to using a bitmap for VMA flags so we can avoid
running out of flags, especially for 32-bit kernels which are constrained
to 32 flags, necessitating some features to be limited to 64-bit kernels
only.

By doing so, we remove any constraint on the number of VMA flags moving
forwards no matter the platform and can decide in future to extend beyond
64 if required.

We start by declaring an opaque types, vma_flags_t (which resembles
mm_struct flags of type mm_flags_t), setting it to precisely the same size
as vm_flags_t, and place it in union with vm_flags in the VMA declaration.

We additionally update struct vm_area_desc equivalently placing the new
opaque type in union with vm_flags.

This change therefore does not impact the size of struct vm_area_struct or
struct vm_area_desc.

In order for the change to be iterative and to avoid impacting
performance, we designate VM_xxx declared bitmap flag values as those
which must exist in the first system word of the VMA flags bitmap.

We therefore declare vma_flags_clear_all(), vma_flags_overwrite_word(),
vma_flags_overwrite_word(), vma_flags_overwrite_word_once(),
vma_flags_set_word() and vma_flags_clear_word() in order to allow us to
update the existing vm_flags_*() functions to utilise these helpers.

This is a stepping stone towards converting users to the VMA flags bitmap
and behaves precisely as before.

By doing this, we can eliminate the existing private vma->__vm_flags field
in the vma->vm_flags union and replace it with the newly introduced opaque
type vma_flags, which we call flags so we refer to the new bitmap field as
vma->flags.

We update vma_flag_[test, set]_atomic() to account for the change also.

We adapt vm_flags_reset_once() to only clear those bits above the first
system word providing write-once semantics to the first system word (which
it is presumed the caller requires - and in all current use cases this is
so).

As we currently only specify that the VMA flags bitmap size is equal to
BITS_PER_LONG number of bits, this is a noop, but is defensive in
preparation for a future change that increases this.

We additionally update the VMA userland test declarations to implement the
same changes there.

Finally, we update the rust code to reference vma->vm_flags on update
rather than vma->__vm_flags which has been removed.  This is safe for now,
albeit it is implicitly performing a const cast.

Once we introduce flag helpers we can improve this more.

No functional change intended.

Link: https://lkml.kernel.org/r/bab179d7b153ac12f221b7d65caac2759282cfe9.1764064557.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: Alice Ryhl <aliceryhl@google.com>	[rust]
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h               |   24 +++-
 include/linux/mm_types.h         |   64 +++++++++++-
 rust/kernel/mm/virt.rs           |    2 
 tools/testing/vma/vma_internal.h |  150 +++++++++++++++++++++++------
 4 files changed, 202 insertions(+), 38 deletions(-)

--- a/include/linux/mm.h~mm-introduce-vma-flags-bitmap-type
+++ a/include/linux/mm.h
@@ -911,7 +911,8 @@ static inline void vm_flags_init(struct
 				 vm_flags_t flags)
 {
 	VM_WARN_ON_ONCE(!pgtable_supports_soft_dirty() && (flags & VM_SOFTDIRTY));
-	ACCESS_PRIVATE(vma, __vm_flags) = flags;
+	vma_flags_clear_all(&vma->flags);
+	vma_flags_overwrite_word(&vma->flags, flags);
 }
 
 /*
@@ -931,14 +932,25 @@ static inline void vm_flags_reset_once(s
 				       vm_flags_t flags)
 {
 	vma_assert_write_locked(vma);
-	WRITE_ONCE(ACCESS_PRIVATE(vma, __vm_flags), flags);
+	/*
+	 * If VMA flags exist beyond the first system word, also clear these. It
+	 * is assumed the write once behaviour is required only for the first
+	 * system word.
+	 */
+	if (NUM_VMA_FLAG_BITS > BITS_PER_LONG) {
+		unsigned long *bitmap = ACCESS_PRIVATE(&vma->flags, __vma_flags);
+
+		bitmap_zero(&bitmap[1], NUM_VMA_FLAG_BITS - BITS_PER_LONG);
+	}
+
+	vma_flags_overwrite_word_once(&vma->flags, flags);
 }
 
 static inline void vm_flags_set(struct vm_area_struct *vma,
 				vm_flags_t flags)
 {
 	vma_start_write(vma);
-	ACCESS_PRIVATE(vma, __vm_flags) |= flags;
+	vma_flags_set_word(&vma->flags, flags);
 }
 
 static inline void vm_flags_clear(struct vm_area_struct *vma,
@@ -946,7 +958,7 @@ static inline void vm_flags_clear(struct
 {
 	VM_WARN_ON_ONCE(!pgtable_supports_soft_dirty() && (flags & VM_SOFTDIRTY));
 	vma_start_write(vma);
-	ACCESS_PRIVATE(vma, __vm_flags) &= ~flags;
+	vma_flags_clear_word(&vma->flags, flags);
 }
 
 /*
@@ -989,12 +1001,14 @@ static inline bool __vma_flag_atomic_val
 static inline void vma_flag_set_atomic(struct vm_area_struct *vma,
 				       vma_flag_t bit)
 {
+	unsigned long *bitmap = ACCESS_PRIVATE(&vma->flags, __vma_flags);
+
 	/* mmap read lock/VMA read lock must be held. */
 	if (!rwsem_is_locked(&vma->vm_mm->mmap_lock))
 		vma_assert_locked(vma);
 
 	if (__vma_flag_atomic_valid(vma, bit))
-		set_bit((__force int)bit, &ACCESS_PRIVATE(vma, __vm_flags));
+		set_bit((__force int)bit, bitmap);
 }
 
 /*
--- a/include/linux/mm_types.h~mm-introduce-vma-flags-bitmap-type
+++ a/include/linux/mm_types.h
@@ -849,6 +849,15 @@ struct mmap_action {
 };
 
 /*
+ * Opaque type representing current VMA (vm_area_struct) flag state. Must be
+ * accessed via vma_flags_xxx() helper functions.
+ */
+#define NUM_VMA_FLAG_BITS BITS_PER_LONG
+typedef struct {
+	DECLARE_BITMAP(__vma_flags, NUM_VMA_FLAG_BITS);
+} __private vma_flags_t;
+
+/*
  * Describes a VMA that is about to be mmap()'ed. Drivers may choose to
  * manipulate mutable fields which will cause those fields to be updated in the
  * resultant VMA.
@@ -865,7 +874,10 @@ struct vm_area_desc {
 	/* Mutable fields. Populated with initial state. */
 	pgoff_t pgoff;
 	struct file *vm_file;
-	vm_flags_t vm_flags;
+	union {
+		vm_flags_t vm_flags;
+		vma_flags_t vma_flags;
+	};
 	pgprot_t page_prot;
 
 	/* Write-only fields. */
@@ -910,10 +922,12 @@ struct vm_area_struct {
 	/*
 	 * Flags, see mm.h.
 	 * To modify use vm_flags_{init|reset|set|clear|mod} functions.
+	 * Preferably, use vma_flags_xxx() functions.
 	 */
 	union {
+		/* Temporary while VMA flags are being converted. */
 		const vm_flags_t vm_flags;
-		vm_flags_t __private __vm_flags;
+		vma_flags_t flags;
 	};
 
 #ifdef CONFIG_PER_VMA_LOCK
@@ -994,6 +1008,52 @@ struct vm_area_struct {
 #endif
 } __randomize_layout;
 
+/* Clears all bits in the VMA flags bitmap, non-atomically. */
+static inline void vma_flags_clear_all(vma_flags_t *flags)
+{
+	bitmap_zero(ACCESS_PRIVATE(flags, __vma_flags), NUM_VMA_FLAG_BITS);
+}
+
+/*
+ * Copy value to the first system word of VMA flags, non-atomically.
+ *
+ * IMPORTANT: This does not overwrite bytes past the first system word. The
+ * caller must account for this.
+ */
+static inline void vma_flags_overwrite_word(vma_flags_t *flags, unsigned long value)
+{
+	*ACCESS_PRIVATE(flags, __vma_flags) = value;
+}
+
+/*
+ * Copy value to the first system word of VMA flags ONCE, non-atomically.
+ *
+ * IMPORTANT: This does not overwrite bytes past the first system word. The
+ * caller must account for this.
+ */
+static inline void vma_flags_overwrite_word_once(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	WRITE_ONCE(*bitmap, value);
+}
+
+/* Update the first system word of VMA flags setting bits, non-atomically. */
+static inline void vma_flags_set_word(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	*bitmap |= value;
+}
+
+/* Update the first system word of VMA flags clearing bits, non-atomically. */
+static inline void vma_flags_clear_word(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	*bitmap &= ~value;
+}
+
 #ifdef CONFIG_NUMA
 #define vma_policy(vma) ((vma)->vm_policy)
 #else
--- a/rust/kernel/mm/virt.rs~mm-introduce-vma-flags-bitmap-type
+++ a/rust/kernel/mm/virt.rs
@@ -250,7 +250,7 @@ impl VmaNew {
         // SAFETY: This is not a data race: the vma is undergoing initial setup, so it's not yet
         // shared. Additionally, `VmaNew` is `!Sync`, so it cannot be used to write in parallel.
         // The caller promises that this does not set the flags to an invalid value.
-        unsafe { (*self.as_ptr()).__bindgen_anon_2.__vm_flags = flags };
+        unsafe { (*self.as_ptr()).__bindgen_anon_2.vm_flags = flags };
     }
 
     /// Set the `VM_MIXEDMAP` flag on this vma.
--- a/tools/testing/vma/vma_internal.h~mm-introduce-vma-flags-bitmap-type
+++ a/tools/testing/vma/vma_internal.h
@@ -524,6 +524,15 @@ typedef struct {
 	__private DECLARE_BITMAP(__mm_flags, NUM_MM_FLAG_BITS);
 } mm_flags_t;
 
+/*
+ * Opaque type representing current VMA (vm_area_struct) flag state. Must be
+ * accessed via vma_flags_xxx() helper functions.
+ */
+#define NUM_VMA_FLAG_BITS BITS_PER_LONG
+typedef struct {
+	DECLARE_BITMAP(__vma_flags, NUM_VMA_FLAG_BITS);
+} __private vma_flags_t;
+
 struct mm_struct {
 	struct maple_tree mm_mt;
 	int map_count;			/* number of VMAs */
@@ -608,7 +617,10 @@ struct vm_area_desc {
 	/* Mutable fields. Populated with initial state. */
 	pgoff_t pgoff;
 	struct file *vm_file;
-	vm_flags_t vm_flags;
+	union {
+		vm_flags_t vm_flags;
+		vma_flags_t vma_flags;
+	};
 	pgprot_t page_prot;
 
 	/* Write-only fields. */
@@ -654,7 +666,7 @@ struct vm_area_struct {
 	 */
 	union {
 		const vm_flags_t vm_flags;
-		vm_flags_t __private __vm_flags;
+		vma_flags_t flags;
 	};
 
 #ifdef CONFIG_PER_VMA_LOCK
@@ -1368,26 +1380,6 @@ static inline bool may_expand_vm(struct
 	return true;
 }
 
-static inline void vm_flags_init(struct vm_area_struct *vma,
-				 vm_flags_t flags)
-{
-	vma->__vm_flags = flags;
-}
-
-static inline void vm_flags_set(struct vm_area_struct *vma,
-				vm_flags_t flags)
-{
-	vma_start_write(vma);
-	vma->__vm_flags |= flags;
-}
-
-static inline void vm_flags_clear(struct vm_area_struct *vma,
-				  vm_flags_t flags)
-{
-	vma_start_write(vma);
-	vma->__vm_flags &= ~flags;
-}
-
 static inline int shmem_zero_setup(struct vm_area_struct *vma)
 {
 	return 0;
@@ -1544,13 +1536,118 @@ static inline void userfaultfd_unmap_com
 {
 }
 
-# define ACCESS_PRIVATE(p, member) ((p)->member)
+#define ACCESS_PRIVATE(p, member) ((p)->member)
+
+#define bitmap_size(nbits)	(ALIGN(nbits, BITS_PER_LONG) / BITS_PER_BYTE)
+
+static __always_inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
+{
+	unsigned int len = bitmap_size(nbits);
+
+	if (small_const_nbits(nbits))
+		*dst = 0;
+	else
+		memset(dst, 0, len);
+}
 
 static inline bool mm_flags_test(int flag, const struct mm_struct *mm)
 {
 	return test_bit(flag, ACCESS_PRIVATE(&mm->flags, __mm_flags));
 }
 
+/* Clears all bits in the VMA flags bitmap, non-atomically. */
+static inline void vma_flags_clear_all(vma_flags_t *flags)
+{
+	bitmap_zero(ACCESS_PRIVATE(flags, __vma_flags), NUM_VMA_FLAG_BITS);
+}
+
+/*
+ * Copy value to the first system word of VMA flags, non-atomically.
+ *
+ * IMPORTANT: This does not overwrite bytes past the first system word. The
+ * caller must account for this.
+ */
+static inline void vma_flags_overwrite_word(vma_flags_t *flags, unsigned long value)
+{
+	*ACCESS_PRIVATE(flags, __vma_flags) = value;
+}
+
+/*
+ * Copy value to the first system word of VMA flags ONCE, non-atomically.
+ *
+ * IMPORTANT: This does not overwrite bytes past the first system word. The
+ * caller must account for this.
+ */
+static inline void vma_flags_overwrite_word_once(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	WRITE_ONCE(*bitmap, value);
+}
+
+/* Update the first system word of VMA flags setting bits, non-atomically. */
+static inline void vma_flags_set_word(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	*bitmap |= value;
+}
+
+/* Update the first system word of VMA flags clearing bits, non-atomically. */
+static inline void vma_flags_clear_word(vma_flags_t *flags, unsigned long value)
+{
+	unsigned long *bitmap = ACCESS_PRIVATE(flags, __vma_flags);
+
+	*bitmap &= ~value;
+}
+
+
+/* Use when VMA is not part of the VMA tree and needs no locking */
+static inline void vm_flags_init(struct vm_area_struct *vma,
+				 vm_flags_t flags)
+{
+	vma_flags_clear_all(&vma->flags);
+	vma_flags_overwrite_word(&vma->flags, flags);
+}
+
+/*
+ * Use when VMA is part of the VMA tree and modifications need coordination
+ * Note: vm_flags_reset and vm_flags_reset_once do not lock the vma and
+ * it should be locked explicitly beforehand.
+ */
+static inline void vm_flags_reset(struct vm_area_struct *vma,
+				  vm_flags_t flags)
+{
+	vma_assert_write_locked(vma);
+	vm_flags_init(vma, flags);
+}
+
+static inline void vm_flags_reset_once(struct vm_area_struct *vma,
+				       vm_flags_t flags)
+{
+	vma_assert_write_locked(vma);
+	/*
+	 * The user should only be interested in avoiding reordering of
+	 * assignment to the first word.
+	 */
+	vma_flags_clear_all(&vma->flags);
+	vma_flags_overwrite_word_once(&vma->flags, flags);
+}
+
+static inline void vm_flags_set(struct vm_area_struct *vma,
+				vm_flags_t flags)
+{
+	vma_start_write(vma);
+	vma_flags_set_word(&vma->flags, flags);
+}
+
+static inline void vm_flags_clear(struct vm_area_struct *vma,
+				  vm_flags_t flags)
+{
+	vma_start_write(vma);
+	vma_flags_clear_word(&vma->flags, flags);
+}
+
 /*
  * Denies creating a writable executable mapping or gaining executable permissions.
  *
@@ -1763,11 +1860,4 @@ static inline int do_munmap(struct mm_st
 	return 0;
 }
 
-static inline void vm_flags_reset(struct vm_area_struct *vma, vm_flags_t flags)
-{
-	vm_flags_t *dst = (vm_flags_t *)(&vma->vm_flags);
-
-	*dst = flags;
-}
-
 #endif	/* __MM_VMA_INTERNAL_H */
_

Patches currently in -mm which might be from lorenzo.stoakes@oracle.com are