[mirror_ubuntu-bionic-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/pagemap.h>
#include <linux/rmap.h>
#include <linux/sched.h>

struct stable_node;
struct mem_cgroup;

#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);
}

static inline struct stable_node *page_stable_node(struct page *page)
{
	return PageKsm(page) ? page_rmapping(page) : NULL;
}

static inline void set_page_stable_node(struct page *page,
					struct stable_node *stable_node)
{
	page->mapping = (void *)((unsigned long)stable_node | PAGE_MAPPING_KSM);
}

/*
 * When do_swap_page() first faults in from swap what used to be a KSM page,
 * no problem, it will be assigned to this vma's anon_vma; but thereafter,
 * it might be faulted into a different anon_vma (or perhaps to a different
 * offset in the same anon_vma).  do_swap_page() cannot do all the locking
 * needed to reconstitute a cross-anon_vma KSM page: for now it has to make
 * a copy, and leave remerging the pages to a later pass of ksmd.
 *
 * We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE,
 * but what if the vma was unmerged while the page was swapped out?
 */
struct page *ksm_might_need_to_copy(struct page *page,
			struct vm_area_struct *vma, unsigned long address);

int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
void ksm_migrate_page(struct page *newpage, struct page *oldpage);

#else  /* !CONFIG_KSM */

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

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

#ifdef CONFIG_MMU
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 struct page *ksm_might_need_to_copy(struct page *page,
			struct vm_area_struct *vma, unsigned long address)
{
	return page;
}

static inline int page_referenced_ksm(struct page *page,
			struct mem_cgroup *memcg, unsigned long *vm_flags)
{
	return 0;
}

static inline int rmap_walk_ksm(struct page *page,
			struct rmap_walk_control *rwc)
{
	return 0;
}

static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage)
{
}
#endif /* CONFIG_MMU */
#endif /* !CONFIG_KSM */

#endif /* __LINUX_KSM_H */
Commit	Line	Data
	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/pagemap.h>
	13	#include <linux/rmap.h>
	14	#include <linux/sched.h>
	15
	16	struct stable_node;
	17	struct mem_cgroup;
	18
	19	#ifdef CONFIG_KSM
	20	int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
	21	unsigned long end, int advice, unsigned long *vm_flags);
	22	int __ksm_enter(struct mm_struct *mm);
	23	void __ksm_exit(struct mm_struct *mm);
	24
	25	static inline int ksm_fork(struct mm_struct mm, struct mm_struct oldmm)
	26	{
	27	if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
	28	return __ksm_enter(mm);
	29	return 0;
	30	}
	31
	32	static inline void ksm_exit(struct mm_struct *mm)
	33	{
	34	if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
	35	__ksm_exit(mm);
	36	}
	37
	38	static inline struct stable_node page_stable_node(struct page page)
	39	{
	40	return PageKsm(page) ? page_rmapping(page) : NULL;
	41	}
	42
	43	static inline void set_page_stable_node(struct page *page,
	44	struct stable_node *stable_node)
	45	{
	46	page->mapping = (void *)((unsigned long)stable_node \| PAGE_MAPPING_KSM);
	47	}
	48
	49	/*
	50	* When do_swap_page() first faults in from swap what used to be a KSM page,
	51	* no problem, it will be assigned to this vma's anon_vma; but thereafter,
	52	* it might be faulted into a different anon_vma (or perhaps to a different
	53	* offset in the same anon_vma). do_swap_page() cannot do all the locking
	54	* needed to reconstitute a cross-anon_vma KSM page: for now it has to make
	55	* a copy, and leave remerging the pages to a later pass of ksmd.
	56	*
	57	* We'd like to make this conditional on vma->vm_flags & VM_MERGEABLE,
	58	* but what if the vma was unmerged while the page was swapped out?
	59	*/
	60	struct page ksm_might_need_to_copy(struct page page,
	61	struct vm_area_struct *vma, unsigned long address);
	62
	63	int rmap_walk_ksm(struct page page, struct rmap_walk_control rwc);
	64	void ksm_migrate_page(struct page newpage, struct page oldpage);
	65
	66	#else /* !CONFIG_KSM */
	67
	68	static inline int ksm_fork(struct mm_struct mm, struct mm_struct oldmm)
	69	{
	70	return 0;
	71	}
	72
	73	static inline void ksm_exit(struct mm_struct *mm)
	74	{
	75	}
	76
	77	#ifdef CONFIG_MMU
	78	static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
	79	unsigned long end, int advice, unsigned long *vm_flags)
	80	{
	81	return 0;
	82	}
	83
	84	static inline struct page ksm_might_need_to_copy(struct page page,
	85	struct vm_area_struct *vma, unsigned long address)
	86	{
	87	return page;
	88	}
	89
	90	static inline int page_referenced_ksm(struct page *page,
	91	struct mem_cgroup memcg, unsigned long vm_flags)
	92	{
	93	return 0;
	94	}
	95
	96	static inline int rmap_walk_ksm(struct page *page,
	97	struct rmap_walk_control *rwc)
	98	{
	99	return 0;
	100	}
	101
	102	static inline void ksm_migrate_page(struct page newpage, struct page oldpage)
	103	{
	104	}
	105	#endif /* CONFIG_MMU */
	106	#endif /* !CONFIG_KSM */
	107
	108	#endif /* __LINUX_KSM_H */