patches/old/mm-replace-mm-flags-with-bitmap-entirely-and-set-to-64-bits.patch

From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: mm: replace mm->flags with bitmap entirely and set to 64 bits
Date: Tue, 12 Aug 2025 16:44:19 +0100

Now we have updated all users of mm->flags to use the bitmap accessors,
repalce it with the bitmap version entirely.

We are then able to move to having 64 bits of mm->flags on both 32-bit and
64-bit architectures.

We also update the VMA userland tests to ensure that everything remains
functional there.

No functional changes intended, other than there now being 64 bits of
available mm_struct flags.

Link: https://lkml.kernel.org/r/e1f6654e016d36c43959764b01355736c5cbcdf8.1755012943.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h               |   12 ++++++------
 include/linux/mm_types.h         |   14 +++++---------
 tools/testing/vma/vma_internal.h |   19 +++++++++++++++++--
 3 files changed, 28 insertions(+), 17 deletions(-)

--- a/include/linux/mm.h~mm-replace-mm-flags-with-bitmap-entirely-and-set-to-64-bits
+++ a/include/linux/mm.h
@@ -724,32 +724,32 @@ static inline void assert_fault_locked(s
 
 static inline bool mm_flags_test(int flag, const struct mm_struct *mm)
 {
-	return test_bit(flag, ACCESS_PRIVATE(&mm->_flags, __mm_flags));
+	return test_bit(flag, ACCESS_PRIVATE(&mm->flags, __mm_flags));
 }
 
 static inline bool mm_flags_test_and_set(int flag, struct mm_struct *mm)
 {
-	return test_and_set_bit(flag, ACCESS_PRIVATE(&mm->_flags, __mm_flags));
+	return test_and_set_bit(flag, ACCESS_PRIVATE(&mm->flags, __mm_flags));
 }
 
 static inline bool mm_flags_test_and_clear(int flag, struct mm_struct *mm)
 {
-	return test_and_clear_bit(flag, ACCESS_PRIVATE(&mm->_flags, __mm_flags));
+	return test_and_clear_bit(flag, ACCESS_PRIVATE(&mm->flags, __mm_flags));
 }
 
 static inline void mm_flags_set(int flag, struct mm_struct *mm)
 {
-	set_bit(flag, ACCESS_PRIVATE(&mm->_flags, __mm_flags));
+	set_bit(flag, ACCESS_PRIVATE(&mm->flags, __mm_flags));
 }
 
 static inline void mm_flags_clear(int flag, struct mm_struct *mm)
 {
-	clear_bit(flag, ACCESS_PRIVATE(&mm->_flags, __mm_flags));
+	clear_bit(flag, ACCESS_PRIVATE(&mm->flags, __mm_flags));
 }
 
 static inline void mm_flags_clear_all(struct mm_struct *mm)
 {
-	bitmap_zero(ACCESS_PRIVATE(&mm->_flags, __mm_flags), NUM_MM_FLAG_BITS);
+	bitmap_zero(ACCESS_PRIVATE(&mm->flags, __mm_flags), NUM_MM_FLAG_BITS);
 }
 
 extern const struct vm_operations_struct vma_dummy_vm_ops;
--- a/include/linux/mm_types.h~mm-replace-mm-flags-with-bitmap-entirely-and-set-to-64-bits
+++ a/include/linux/mm_types.h
@@ -932,7 +932,7 @@ struct mm_cid {
  * Opaque type representing current mm_struct flag state. Must be accessed via
  * mm_flags_xxx() helper functions.
  */
-#define NUM_MM_FLAG_BITS BITS_PER_LONG
+#define NUM_MM_FLAG_BITS (64)
 typedef struct {
 	DECLARE_BITMAP(__mm_flags, NUM_MM_FLAG_BITS);
 } __private mm_flags_t;
@@ -1119,11 +1119,7 @@ struct mm_struct {
 		/* Architecture-specific MM context */
 		mm_context_t context;
 
-		/* Temporary union while we convert users to mm_flags_t. */
-		union {
-			unsigned long flags; /* Must use atomic bitops to access */
-			mm_flags_t _flags;   /* Must use mm_flags_* helpers to access */
-		};
+		mm_flags_t flags; /* Must use mm_flags_* hlpers to access */
 
 #ifdef CONFIG_AIO
 		spinlock_t			ioctx_lock;
@@ -1236,7 +1232,7 @@ struct mm_struct {
 /* Set the first system word of mm flags, non-atomically. */
 static inline void __mm_flags_set_word(struct mm_struct *mm, unsigned long value)
 {
-	unsigned long *bitmap = ACCESS_PRIVATE(&mm->_flags, __mm_flags);
+	unsigned long *bitmap = ACCESS_PRIVATE(&mm->flags, __mm_flags);
 
 	bitmap_copy(bitmap, &value, BITS_PER_LONG);
 }
@@ -1244,7 +1240,7 @@ static inline void __mm_flags_set_word(s
 /* Obtain a read-only view of the bitmap. */
 static inline const unsigned long *__mm_flags_get_bitmap(const struct mm_struct *mm)
 {
-	return (const unsigned long *)ACCESS_PRIVATE(&mm->_flags, __mm_flags);
+	return (const unsigned long *)ACCESS_PRIVATE(&mm->flags, __mm_flags);
 }
 
 /* Read the first system word of mm flags, non-atomically. */
@@ -1262,7 +1258,7 @@ static inline unsigned long __mm_flags_g
 static inline void __mm_flags_set_mask_bits_word(struct mm_struct *mm,
 		unsigned long mask, unsigned long bits)
 {
-	unsigned long *bitmap = ACCESS_PRIVATE(&mm->_flags, __mm_flags);
+	unsigned long *bitmap = ACCESS_PRIVATE(&mm->flags, __mm_flags);
 
 	set_mask_bits(bitmap, mask, bits);
 }
--- a/tools/testing/vma/vma_internal.h~mm-replace-mm-flags-with-bitmap-entirely-and-set-to-64-bits
+++ a/tools/testing/vma/vma_internal.h
@@ -249,6 +249,14 @@ struct mutex {};
 #define DEFINE_MUTEX(mutexname) \
 	struct mutex mutexname = {}
 
+#define DECLARE_BITMAP(name, bits) \
+	unsigned long name[BITS_TO_LONGS(bits)]
+
+#define NUM_MM_FLAG_BITS (64)
+typedef struct {
+	__private DECLARE_BITMAP(__mm_flags, NUM_MM_FLAG_BITS);
+} mm_flags_t;
+
 struct mm_struct {
 	struct maple_tree mm_mt;
 	int map_count;			/* number of VMAs */
@@ -260,7 +268,7 @@ struct mm_struct {
 
 	unsigned long def_flags;
 
-	unsigned long flags; /* Must use atomic bitops to access */
+	mm_flags_t flags; /* Must use mm_flags_* helpers to access */
 };
 
 struct vm_area_struct;
@@ -1333,6 +1341,13 @@ static inline void userfaultfd_unmap_com
 {
 }
 
+# define ACCESS_PRIVATE(p, member) ((p)->member)
+
+static inline bool mm_flags_test(int flag, const struct mm_struct *mm)
+{
+	return test_bit(flag, ACCESS_PRIVATE(&mm->flags, __mm_flags));
+}
+
 /*
  * Denies creating a writable executable mapping or gaining executable permissions.
  *
@@ -1363,7 +1378,7 @@ static inline void userfaultfd_unmap_com
 static inline bool map_deny_write_exec(unsigned long old, unsigned long new)
 {
 	/* If MDWE is disabled, we have nothing to deny. */
-	if (!test_bit(MMF_HAS_MDWE, &current->mm->flags))
+	if (mm_flags_test(MMF_HAS_MDWE, current->mm))
 		return false;
 
 	/* If the new VMA is not executable, we have nothing to deny. */
_