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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_MIGRATE_H
#define _LINUX_MIGRATE_H
#include <linux/mm.h>
#include <linux/mempolicy.h>
#include <linux/migrate_mode.h>
#include <linux/hugetlb.h>
typedef struct page *new_page_t(struct page *page, unsigned long private);
typedef void free_page_t(struct page *page, unsigned long private);
struct migration_target_control;
/*
* Return values from addresss_space_operations.migratepage():
* - negative errno on page migration failure;
* - zero on page migration success;
*/
#define MIGRATEPAGE_SUCCESS 0
/**
* struct movable_operations - Driver page migration
* @isolate_page:
* The VM calls this function to prepare the page to be moved. The page
* is locked and the driver should not unlock it. The driver should
* return ``true`` if the page is movable and ``false`` if it is not
* currently movable. After this function returns, the VM uses the
* page->lru field, so the driver must preserve any information which
* is usually stored here.
*
* @migrate_page:
* After isolation, the VM calls this function with the isolated
* @src page. The driver should copy the contents of the
* @src page to the @dst page and set up the fields of @dst page.
* Both pages are locked.
* If page migration is successful, the driver should call
* __ClearPageMovable(@src) and return MIGRATEPAGE_SUCCESS.
* If the driver cannot migrate the page at the moment, it can return
* -EAGAIN. The VM interprets this as a temporary migration failure and
* will retry it later. Any other error value is a permanent migration
* failure and migration will not be retried.
* The driver shouldn't touch the @src->lru field while in the
* migrate_page() function. It may write to @dst->lru.
*
* @putback_page:
* If migration fails on the isolated page, the VM informs the driver
* that the page is no longer a candidate for migration by calling
* this function. The driver should put the isolated page back into
* its own data structure.
*/
struct movable_operations {
bool (*isolate_page)(struct page *, isolate_mode_t);
int (*migrate_page)(struct page *dst, struct page *src,
enum migrate_mode);
void (*putback_page)(struct page *);
};
/* Defined in mm/debug.c: */
extern const char *migrate_reason_names[MR_TYPES];
#ifdef CONFIG_MIGRATION
extern void putback_movable_pages(struct list_head *l);
int migrate_folio(struct address_space *mapping, struct folio *dst,
struct folio *src, enum migrate_mode mode);
extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
unsigned long private, enum migrate_mode mode, int reason,
unsigned int *ret_succeeded);
extern struct page *alloc_migration_target(struct page *page, unsigned long private);
extern int isolate_movable_page(struct page *page, isolate_mode_t mode);
int migrate_huge_page_move_mapping(struct address_space *mapping,
struct folio *dst, struct folio *src);
void migration_entry_wait_on_locked(swp_entry_t entry, pte_t *ptep,
spinlock_t *ptl);
void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
void folio_migrate_copy(struct folio *newfolio, struct folio *folio);
int folio_migrate_mapping(struct address_space *mapping,
struct folio *newfolio, struct folio *folio, int extra_count);
#else
static inline void putback_movable_pages(struct list_head *l) {}
static inline int migrate_pages(struct list_head *l, new_page_t new,
free_page_t free, unsigned long private, enum migrate_mode mode,
int reason, unsigned int *ret_succeeded)
{ return -ENOSYS; }
static inline struct page *alloc_migration_target(struct page *page,
unsigned long private)
{ return NULL; }
static inline int isolate_movable_page(struct page *page, isolate_mode_t mode)
{ return -EBUSY; }
static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
struct folio *dst, struct folio *src)
{
return -ENOSYS;
}
#endif /* CONFIG_MIGRATION */
#if defined(CONFIG_MIGRATION) && defined(CONFIG_NUMA)
extern void set_migration_target_nodes(void);
extern void migrate_on_reclaim_init(void);
extern bool numa_demotion_enabled;
extern int next_demotion_node(int node);
#else
static inline void set_migration_target_nodes(void) {}
static inline void migrate_on_reclaim_init(void) {}
static inline int next_demotion_node(int node)
{
return NUMA_NO_NODE;
}
#define numa_demotion_enabled false
#endif
#ifdef CONFIG_COMPACTION
bool PageMovable(struct page *page);
void __SetPageMovable(struct page *page, const struct movable_operations *ops);
void __ClearPageMovable(struct page *page);
#else
static inline bool PageMovable(struct page *page) { return false; }
static inline void __SetPageMovable(struct page *page,
const struct movable_operations *ops)
{
}
static inline void __ClearPageMovable(struct page *page)
{
}
#endif
static inline bool folio_test_movable(struct folio *folio)
{
return PageMovable(&folio->page);
}
static inline
const struct movable_operations *page_movable_ops(struct page *page)
{
VM_BUG_ON(!__PageMovable(page));
return (const struct movable_operations *)
((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
}
#ifdef CONFIG_NUMA_BALANCING
extern int migrate_misplaced_page(struct page *page,
struct vm_area_struct *vma, int node);
#else
static inline int migrate_misplaced_page(struct page *page,
struct vm_area_struct *vma, int node)
{
return -EAGAIN; /* can't migrate now */
}
#endif /* CONFIG_NUMA_BALANCING */
#ifdef CONFIG_MIGRATION
/*
* Watch out for PAE architecture, which has an unsigned long, and might not
* have enough bits to store all physical address and flags. So far we have
* enough room for all our flags.
*/
#define MIGRATE_PFN_VALID (1UL << 0)
#define MIGRATE_PFN_MIGRATE (1UL << 1)
#define MIGRATE_PFN_WRITE (1UL << 3)
#define MIGRATE_PFN_SHIFT 6
static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
{
if (!(mpfn & MIGRATE_PFN_VALID))
return NULL;
return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT);
}
static inline unsigned long migrate_pfn(unsigned long pfn)
{
return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
}
enum migrate_vma_direction {
MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
};
struct migrate_vma {
struct vm_area_struct *vma;
/*
* Both src and dst array must be big enough for
* (end - start) >> PAGE_SHIFT entries.
*
* The src array must not be modified by the caller after
* migrate_vma_setup(), and must not change the dst array after
* migrate_vma_pages() returns.
*/
unsigned long *dst;
unsigned long *src;
unsigned long cpages;
unsigned long npages;
unsigned long start;
unsigned long end;
/*
* Set to the owner value also stored in page->pgmap->owner for
* migrating out of device private memory. The flags also need to
* be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE.
* The caller should always set this field when using mmu notifier
* callbacks to avoid device MMU invalidations for device private
* pages that are not being migrated.
*/
void *pgmap_owner;
unsigned long flags;
};
int migrate_vma_setup(struct migrate_vma *args);
void migrate_vma_pages(struct migrate_vma *migrate);
void migrate_vma_finalize(struct migrate_vma *migrate);
#endif /* CONFIG_MIGRATION */
#endif /* _LINUX_MIGRATE_H */
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