Re: [PATCH 01/10] mm: add bitmap mm->flags field

Lorenzo Stoakes
2025-08-13T19:54:52Z

Hi Andrew,

Apologies, it turns out I put the __private sparse decorator in the wrong
place :)

I enclose a fix-patch that fixes this (now *ahem* tested with sparse...) as
well as fixing some trivial whitespace/code reuse/const stuff in a couple
accessors.

Cheers, Lorenzo

----8<----
From cbe60f2c5e35bf1fcffb00c51f79f700edc17e06 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Date: Wed, 13 Aug 2025 20:40:10 +0100
Subject: [PATCH] mm: place __private in correct place, const-ify
__mm_flags_get_word

The __private sparse indicator was placed in the wrong location, resulting
in sparse errors, correct this by placing it where it ought to be.

Also, share some code for __mm_flags_get_word() and const-ify it to be
consistent.

Finally, fixup inconsistency in __mm_flags_set_word() param alignment.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
include/linux/mm_types.h | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 46d3fb8935c7..0e001dbad455 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -934,8 +934,8 @@ struct mm_cid {
*/
#define NUM_MM_FLAG_BITS BITS_PER_LONG
typedef struct {
- __private DECLARE_BITMAP(__mm_flags, NUM_MM_FLAG_BITS);
-} mm_flags_t;
+ DECLARE_BITMAP(__mm_flags, NUM_MM_FLAG_BITS);
+} __private mm_flags_t;

struct kioctx_table;
struct iommu_mm_data;
@@ -1233,17 +1233,8 @@ struct mm_struct {
unsigned long cpu_bitmap[];
};

-/* Read the first system word of mm flags, non-atomically. */
-static inline unsigned long __mm_flags_get_word(struct mm_struct *mm)
-{
- unsigned long *bitmap = ACCESS_PRIVATE(&mm->_flags, __mm_flags);
-
- return bitmap_read(bitmap, 0, BITS_PER_LONG);
-}
-
/* Set the first system word of mm flags, non-atomically. */
-static inline void __mm_flags_set_word(struct mm_struct *mm,
- unsigned long value)
+static inline void __mm_flags_set_word(struct mm_struct *mm, unsigned long value)
{
unsigned long *bitmap = ACCESS_PRIVATE(&mm->_flags, __mm_flags);

@@ -1256,6 +1247,14 @@ static inline const unsigned long *__mm_flags_get_bitmap(const struct mm_struct
return (const unsigned long *)ACCESS_PRIVATE(&mm->_flags, __mm_flags);
}

+/* Read the first system word of mm flags, non-atomically. */
+static inline unsigned long __mm_flags_get_word(const struct mm_struct *mm)
+{
+ const unsigned long *bitmap = __mm_flags_get_bitmap(mm);
+
+ return bitmap_read(bitmap, 0, BITS_PER_LONG);
+}
+
#define MM_MT_FLAGS (MT_FLAGS_ALLOC_RANGE | MT_FLAGS_LOCK_EXTERN | \
MT_FLAGS_USE_RCU)
extern struct mm_struct init_mm;
--
2.50.1