[mirror_ubuntu-artful-kernel.git] / include / linux / ksm.h

#ifndef __LINUX_KSM_H
#define __LINUX_KSM_H
/*
 * Memory merging support.
 *
 * This code enables dynamic sharing of identical pages found in different
 * memory areas, even if they are not shared by fork().
 */

#include <linux/bitops.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/vmstat.h>

#ifdef CONFIG_KSM
int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
		unsigned long end, int advice, unsigned long *vm_flags);
int __ksm_enter(struct mm_struct *mm);
void __ksm_exit(struct mm_struct *mm);

static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
	if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
		return __ksm_enter(mm);
	return 0;
}

static inline void ksm_exit(struct mm_struct *mm)
{
	if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
		__ksm_exit(mm);
}

/*
 * A KSM page is one of those write-protected "shared pages" or "merged pages"
 * which KSM maps into multiple mms, wherever identical anonymous page content
 * is found in VM_MERGEABLE vmas.  It's a PageAnon page, with NULL anon_vma.
 */
static inline int PageKsm(struct page *page)
{
	return ((unsigned long)page->mapping == PAGE_MAPPING_ANON);
}

/*
 * But we have to avoid the checking which page_add_anon_rmap() performs.
 */
static inline void page_add_ksm_rmap(struct page *page)
{
	if (atomic_inc_and_test(&page->_mapcount)) {
		page->mapping = (void *) PAGE_MAPPING_ANON;
		__inc_zone_page_state(page, NR_ANON_PAGES);
	}
}
#else  /* !CONFIG_KSM */

static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
		unsigned long end, int advice, unsigned long *vm_flags)
{
	return 0;
}

static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
	return 0;
}

static inline void ksm_exit(struct mm_struct *mm)
{
}

static inline int PageKsm(struct page *page)
{
	return 0;
}

/* No stub required for page_add_ksm_rmap(page) */
#endif /* !CONFIG_KSM */

#endif
Commit	Line	Data
f8af4da3 HD	1	#ifndef __LINUX_KSM_H
	2	#define __LINUX_KSM_H
	3	/*
	4	* Memory merging support.
	5	*
	6	* This code enables dynamic sharing of identical pages found in different
	7	* memory areas, even if they are not shared by fork().
	8	*/
	9
	10	#include <linux/bitops.h>
	11	#include <linux/mm.h>
	12	#include <linux/sched.h>
9a840895	13	#include <linux/vmstat.h>
f8af4da3 HD	14
	15	#ifdef CONFIG_KSM
	16	int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
	17	unsigned long end, int advice, unsigned long *vm_flags);
	18	int __ksm_enter(struct mm_struct *mm);
1c2fb7a4	19	void __ksm_exit(struct mm_struct *mm);
f8af4da3 HD	20
	21	static inline int ksm_fork(struct mm_struct mm, struct mm_struct oldmm)
	22	{
	23	if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
	24	return __ksm_enter(mm);
	25	return 0;
	26	}
	27
1c2fb7a4	28	static inline void ksm_exit(struct mm_struct *mm)
f8af4da3 HD	29	{
f8af4da3 HD	30	if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
1c2fb7a4	31	__ksm_exit(mm);
f8af4da3	32	}
9a840895 HD	33
	34	/*
	35	* A KSM page is one of those write-protected "shared pages" or "merged pages"
	36	* which KSM maps into multiple mms, wherever identical anonymous page content
	37	* is found in VM_MERGEABLE vmas. It's a PageAnon page, with NULL anon_vma.
	38	*/
	39	static inline int PageKsm(struct page *page)
	40	{
	41	return ((unsigned long)page->mapping == PAGE_MAPPING_ANON);
	42	}
	43
	44	/*
	45	* But we have to avoid the checking which page_add_anon_rmap() performs.
	46	*/
	47	static inline void page_add_ksm_rmap(struct page *page)
	48	{
	49	if (atomic_inc_and_test(&page->_mapcount)) {
	50	page->mapping = (void *) PAGE_MAPPING_ANON;
	51	__inc_zone_page_state(page, NR_ANON_PAGES);
	52	}
	53	}
f8af4da3 HD	54	#else /* !CONFIG_KSM */
	55
	56	static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
	57	unsigned long end, int advice, unsigned long *vm_flags)
	58	{
	59	return 0;
	60	}
	61
	62	static inline int ksm_fork(struct mm_struct mm, struct mm_struct oldmm)
	63	{
	64	return 0;
	65	}
	66
1c2fb7a4	67	static inline void ksm_exit(struct mm_struct *mm)
f8af4da3 HD	68	{
f8af4da3 HD	69	}
9a840895 HD	70
	71	static inline int PageKsm(struct page *page)
	72	{
	73	return 0;
	74	}
	75
	76	/* No stub required for page_add_ksm_rmap(page) */
f8af4da3 HD	77	#endif /* !CONFIG_KSM */
	78
	79	#endif