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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_MIGRATE_H
3#define _LINUX_MIGRATE_H
4
5#include <linux/mm.h>
6#include <linux/mempolicy.h>
7#include <linux/migrate_mode.h>
8#include <linux/hugetlb.h>
9
10typedef struct page *new_page_t(struct page *page, unsigned long private);
11typedef void free_page_t(struct page *page, unsigned long private);
12
13struct migration_target_control;
14
15/*
16 * Return values from addresss_space_operations.migratepage():
17 * - negative errno on page migration failure;
18 * - zero on page migration success;
19 */
20#define MIGRATEPAGE_SUCCESS 0
21
22/**
23 * struct movable_operations - Driver page migration
24 * @isolate_page:
25 * The VM calls this function to prepare the page to be moved. The page
26 * is locked and the driver should not unlock it. The driver should
27 * return ``true`` if the page is movable and ``false`` if it is not
28 * currently movable. After this function returns, the VM uses the
29 * page->lru field, so the driver must preserve any information which
30 * is usually stored here.
31 *
32 * @migrate_page:
33 * After isolation, the VM calls this function with the isolated
34 * @src page. The driver should copy the contents of the
35 * @src page to the @dst page and set up the fields of @dst page.
36 * Both pages are locked.
37 * If page migration is successful, the driver should call
38 * __ClearPageMovable(@src) and return MIGRATEPAGE_SUCCESS.
39 * If the driver cannot migrate the page at the moment, it can return
40 * -EAGAIN. The VM interprets this as a temporary migration failure and
41 * will retry it later. Any other error value is a permanent migration
42 * failure and migration will not be retried.
43 * The driver shouldn't touch the @src->lru field while in the
44 * migrate_page() function. It may write to @dst->lru.
45 *
46 * @putback_page:
47 * If migration fails on the isolated page, the VM informs the driver
48 * that the page is no longer a candidate for migration by calling
49 * this function. The driver should put the isolated page back into
50 * its own data structure.
51 */
52struct movable_operations {
53 bool (*isolate_page)(struct page *, isolate_mode_t);
54 int (*migrate_page)(struct page *dst, struct page *src,
55 enum migrate_mode);
56 void (*putback_page)(struct page *);
57};
58
59/* Defined in mm/debug.c: */
60extern const char *migrate_reason_names[MR_TYPES];
61
62#ifdef CONFIG_MIGRATION
63
64extern void putback_movable_pages(struct list_head *l);
65int migrate_folio(struct address_space *mapping, struct folio *dst,
66 struct folio *src, enum migrate_mode mode);
67extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
68 unsigned long private, enum migrate_mode mode, int reason,
69 unsigned int *ret_succeeded);
70extern struct page *alloc_migration_target(struct page *page, unsigned long private);
71extern int isolate_movable_page(struct page *page, isolate_mode_t mode);
72
73int migrate_huge_page_move_mapping(struct address_space *mapping,
74 struct folio *dst, struct folio *src);
75void migration_entry_wait_on_locked(swp_entry_t entry, pte_t *ptep,
76 spinlock_t *ptl);
77void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
78void folio_migrate_copy(struct folio *newfolio, struct folio *folio);
79int folio_migrate_mapping(struct address_space *mapping,
80 struct folio *newfolio, struct folio *folio, int extra_count);
81
82#else
83
84static inline void putback_movable_pages(struct list_head *l) {}
85static inline int migrate_pages(struct list_head *l, new_page_t new,
86 free_page_t free, unsigned long private, enum migrate_mode mode,
87 int reason, unsigned int *ret_succeeded)
88 { return -ENOSYS; }
89static inline struct page *alloc_migration_target(struct page *page,
90 unsigned long private)
91 { return NULL; }
92static inline int isolate_movable_page(struct page *page, isolate_mode_t mode)
93 { return -EBUSY; }
94
95static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
96 struct folio *dst, struct folio *src)
97{
98 return -ENOSYS;
99}
100
101#endif /* CONFIG_MIGRATION */
102
103#if defined(CONFIG_MIGRATION) && defined(CONFIG_NUMA)
104extern void set_migration_target_nodes(void);
105extern void migrate_on_reclaim_init(void);
106extern bool numa_demotion_enabled;
107extern int next_demotion_node(int node);
108#else
109static inline void set_migration_target_nodes(void) {}
110static inline void migrate_on_reclaim_init(void) {}
111static inline int next_demotion_node(int node)
112{
113 return NUMA_NO_NODE;
114}
115#define numa_demotion_enabled false
116#endif
117
118#ifdef CONFIG_COMPACTION
119bool PageMovable(struct page *page);
120void __SetPageMovable(struct page *page, const struct movable_operations *ops);
121void __ClearPageMovable(struct page *page);
122#else
123static inline bool PageMovable(struct page *page) { return false; }
124static inline void __SetPageMovable(struct page *page,
125 const struct movable_operations *ops)
126{
127}
128static inline void __ClearPageMovable(struct page *page)
129{
130}
131#endif
132
133static inline bool folio_test_movable(struct folio *folio)
134{
135 return PageMovable(&folio->page);
136}
137
138static inline
139const struct movable_operations *page_movable_ops(struct page *page)
140{
141 VM_BUG_ON(!__PageMovable(page));
142
143 return (const struct movable_operations *)
144 ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
145}
146
147#ifdef CONFIG_NUMA_BALANCING
148extern int migrate_misplaced_page(struct page *page,
149 struct vm_area_struct *vma, int node);
150#else
151static inline int migrate_misplaced_page(struct page *page,
152 struct vm_area_struct *vma, int node)
153{
154 return -EAGAIN; /* can't migrate now */
155}
156#endif /* CONFIG_NUMA_BALANCING */
157
158#ifdef CONFIG_MIGRATION
159
160/*
161 * Watch out for PAE architecture, which has an unsigned long, and might not
162 * have enough bits to store all physical address and flags. So far we have
163 * enough room for all our flags.
164 */
165#define MIGRATE_PFN_VALID (1UL << 0)
166#define MIGRATE_PFN_MIGRATE (1UL << 1)
167#define MIGRATE_PFN_WRITE (1UL << 3)
168#define MIGRATE_PFN_SHIFT 6
169
170static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
171{
172 if (!(mpfn & MIGRATE_PFN_VALID))
173 return NULL;
174 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT);
175}
176
177static inline unsigned long migrate_pfn(unsigned long pfn)
178{
179 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
180}
181
182enum migrate_vma_direction {
183 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
184 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
185 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2,
186};
187
188struct migrate_vma {
189 struct vm_area_struct *vma;
190 /*
191 * Both src and dst array must be big enough for
192 * (end - start) >> PAGE_SHIFT entries.
193 *
194 * The src array must not be modified by the caller after
195 * migrate_vma_setup(), and must not change the dst array after
196 * migrate_vma_pages() returns.
197 */
198 unsigned long *dst;
199 unsigned long *src;
200 unsigned long cpages;
201 unsigned long npages;
202 unsigned long start;
203 unsigned long end;
204
205 /*
206 * Set to the owner value also stored in page->pgmap->owner for
207 * migrating out of device private memory. The flags also need to
208 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE.
209 * The caller should always set this field when using mmu notifier
210 * callbacks to avoid device MMU invalidations for device private
211 * pages that are not being migrated.
212 */
213 void *pgmap_owner;
214 unsigned long flags;
215};
216
217int migrate_vma_setup(struct migrate_vma *args);
218void migrate_vma_pages(struct migrate_vma *migrate);
219void migrate_vma_finalize(struct migrate_vma *migrate);
220#endif /* CONFIG_MIGRATION */
221
222#endif /* _LINUX_MIGRATE_H */