mm: cma: make mm/cma.h self-contained and conditionalize includes

PATCH Superseded Eamon Sippy 2 participants 4 messages Aug 15 Memory management

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Eamon Sippy

author

2026-08-15 08:40 UTC #0 lore raw

PATCH 1/1 mm: cma: make mm/cma.h self-contained and conditionalize includes

mm/cma.h uses types from <linux/spinlock.h>, <linux/mutex.h>, <linux/atomic.h> and <linux/list.h> without explicitly including them, violating the kernel header self-containment guidelines.

<linux/debugfs.h> and <linux/kobject.h> are also included unconditionally even though they are only needed under CONFIG_CMA_DEBUGFS and CONFIG_CMA_SYSFS respectively. Move the struct cma_kobject definition and <linux/kobject.h> inside the CONFIG_CMA_SYSFS block, and move <linux/debugfs.h> inside CONFIG_CMA_DEBUGFS.

Remove spurious trailing semicolons after the empty inline function bodies in the CONFIG_CMA_SYSFS #else branch.

Add <linux/cma.h> so that MAX_CMA_AREAS and CMA_MAX_NAME are always available when this header is included.

Signed-off-by Eamon Sippy <[email protected]>

---
 mm/cma.h | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

mm/cma.h +18 -6

index c70180c36559..0a1cb0141756 100644
@@ -2,13 +2,24 @@
 #ifndef __MM_CMA_H__
 #define __MM_CMA_H__
 
+#include <linux/atomic.h>
+#include <linux/cma.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+
+#ifdef CONFIG_CMA_DEBUGFS
 #include <linux/debugfs.h>
+#endif
+
+#ifdef CONFIG_CMA_SYSFS
 #include <linux/kobject.h>
 
 struct cma_kobject {
 	struct kobject kobj;
 	struct cma *cma;
 };
+#endif
 
 /*
  * Multi-range support. This can be useful if the size of the allocation

@@ -37,10 +48,10 @@ struct cma_memrange {
 #define CMA_MAX_RANGES 8
 
 struct cma {
-	unsigned long   count;
-	unsigned long	available_count;
+	unsigned long count;
+	unsigned long available_count;
 	unsigned int order_per_bit; /* Order of pages represented by one bit */
-	spinlock_t	lock;
+	spinlock_t lock;	/* protects allocation bitmap */
 	struct mutex alloc_mutex;
 #ifdef CONFIG_CMA_DEBUGFS
 	struct hlist_head mem_head;

@@ -86,10 +97,11 @@ void cma_sysfs_account_fail_pages(struct cma *cma, unsigned long nr_pages);
 void cma_sysfs_account_release_pages(struct cma *cma, unsigned long nr_pages);
 #else
 static inline void cma_sysfs_account_success_pages(struct cma *cma,
-						   unsigned long nr_pages) {};
+						   unsigned long nr_pages) {}
 static inline void cma_sysfs_account_fail_pages(struct cma *cma,
-						unsigned long nr_pages) {};
+						unsigned long nr_pages) {}
 static inline void cma_sysfs_account_release_pages(struct cma *cma,
-						   unsigned long nr_pages) {};
+						   unsigned long nr_pages) {}
 #endif
+
 #endif

Signature · 1 line

2.43.0

Barry Song

2026-08-15 10:03 UTC #1 lore raw

Quoted 18 lines · Eamon Sippy

mm/cma.h uses types from <linux/spinlock.h>, <linux/mutex.h>, <linux/atomic.h> and <linux/list.h> without explicitly including them, violating the kernel header self-containment guidelines.
<linux/debugfs.h> and <linux/kobject.h> are also included unconditionally even though they are only needed under CONFIG_CMA_DEBUGFS and CONFIG_CMA_SYSFS respectively. Move the struct cma_kobject definition and <linux/kobject.h> inside the CONFIG_CMA_SYSFS block, and move <linux/debugfs.h> inside CONFIG_CMA_DEBUGFS.
Remove spurious trailing semicolons after the empty inline function bodies in the CONFIG_CMA_SYSFS #else branch.
Add <linux/cma.h> so that MAX_CMA_AREAS and CMA_MAX_NAME are always available when this header is included.
Signed-off-by Eamon Sippy <[email protected]>

[...]

mm/cma.h struct cma_memrange { · line 54

Quoted 4 lines

mm/cma.h +2 -1

+       unsigned long available_count;
        unsigned int order_per_bit; /* Order of pages represented by one bit */
-       spinlock_t      lock;
+       spinlock_t lock;        /* protects allocation bitmap */

I’m not convinced this lock is only for protecting the bitmap. It also protects things such as cma->available_count and the allocation checks around page_range_contiguous(). Could we drop the added comment or use a more accurate description?

Quoted 1 line

        struct mutex alloc_mutex;

Best Regards
Barry

Eamon Sippy

author

2026-08-15 10:33 UTC #2 lore raw

PATCH v2 1/1 mm: cma: make mm/cma.h self-contained and conditionalize includes

In reply to Eamon Sippy

mm/cma.h uses types from <linux/spinlock.h>, <linux/mutex.h>, <linux/atomic.h> and <linux/list.h> without explicitly including them, violating the kernel header self-containment guidelines.

Remove spurious trailing semicolons after the empty inline function bodies in the CONFIG_CMA_SYSFS #else branch.

Add <linux/cma.h> so that MAX_CMA_AREAS and CMA_MAX_NAME are always available when this header is included.

Changes in v2:
- Drop inaccurate spinlock comment; the lock also protects available_count and allocation checks (Barry)

Signed-off-by Eamon Sippy <[email protected]>

---
 mm/cma.h | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

mm/cma.h +18 -6

index c70180c36559..68e574b0f951 100644
@@ -2,13 +2,24 @@
 #ifndef __MM_CMA_H__
 #define __MM_CMA_H__
 
+#include <linux/atomic.h>
+#include <linux/cma.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+
+#ifdef CONFIG_CMA_DEBUGFS
 #include <linux/debugfs.h>
+#endif
+
+#ifdef CONFIG_CMA_SYSFS
 #include <linux/kobject.h>
 
 struct cma_kobject {
 	struct kobject kobj;
 	struct cma *cma;
 };
+#endif
 
 /*
  * Multi-range support. This can be useful if the size of the allocation

@@ -37,10 +48,10 @@ struct cma_memrange {
 #define CMA_MAX_RANGES 8
 
 struct cma {
-	unsigned long   count;
-	unsigned long	available_count;
+	unsigned long count;
+	unsigned long available_count;
 	unsigned int order_per_bit; /* Order of pages represented by one bit */
-	spinlock_t	lock;
+	spinlock_t lock;
 	struct mutex alloc_mutex;
 #ifdef CONFIG_CMA_DEBUGFS
 	struct hlist_head mem_head;

@@ -86,10 +97,11 @@ void cma_sysfs_account_fail_pages(struct cma *cma, unsigned long nr_pages);
 void cma_sysfs_account_release_pages(struct cma *cma, unsigned long nr_pages);
 #else
 static inline void cma_sysfs_account_success_pages(struct cma *cma,
-						   unsigned long nr_pages) {};
+						   unsigned long nr_pages) {}
 static inline void cma_sysfs_account_fail_pages(struct cma *cma,
-						unsigned long nr_pages) {};
+						unsigned long nr_pages) {}
 static inline void cma_sysfs_account_release_pages(struct cma *cma,
-						   unsigned long nr_pages) {};
+						   unsigned long nr_pages) {}
 #endif
+
 #endif

Signature · 1 line

2.43.0

Barry Song

Reviewed-by on v2 1/1

2026-08-15 11:36 UTC #3 lore raw

Quoted 17 lines · Eamon Sippy

mm/cma.h uses types from <linux/spinlock.h>, <linux/mutex.h>, <linux/atomic.h> and <linux/list.h> without explicitly including them, violating the kernel header self-containment guidelines.
<linux/debugfs.h> and <linux/kobject.h> are also included unconditionally even though they are only needed under CONFIG_CMA_DEBUGFS and CONFIG_CMA_SYSFS respectively. Move the struct cma_kobject definition and <linux/kobject.h> inside the CONFIG_CMA_SYSFS block, and move <linux/debugfs.h> inside CONFIG_CMA_DEBUGFS.
Remove spurious trailing semicolons after the empty inline function bodies in the CONFIG_CMA_SYSFS #else branch.
Add <linux/cma.h> so that MAX_CMA_AREAS and CMA_MAX_NAME are always available when this header is included.

Quoted 6 lines

Changes in v2:
- Drop inaccurate spinlock comment; the lock also protects available_count and allocation checks (Barry)
Signed-off-by Eamon Sippy <[email protected]>
---

Reviewed-by Barry Song <[email protected]>