Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 folio *new_folio_t(struct folio *folio, unsigned long private);
11typedef void free_folio_t(struct folio *folio, 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#define MIGRATEPAGE_UNMAP 1
22
23/**
24 * struct movable_operations - Driver page migration
25 * @isolate_page:
26 * The VM calls this function to prepare the page to be moved. The page
27 * is locked and the driver should not unlock it. The driver should
28 * return ``true`` if the page is movable and ``false`` if it is not
29 * currently movable. After this function returns, the VM uses the
30 * page->lru field, so the driver must preserve any information which
31 * is usually stored here.
32 *
33 * @migrate_page:
34 * After isolation, the VM calls this function with the isolated
35 * @src page. The driver should copy the contents of the
36 * @src page to the @dst page and set up the fields of @dst page.
37 * Both pages are locked.
38 * If page migration is successful, the driver should
39 * return MIGRATEPAGE_SUCCESS.
40 * If the driver cannot migrate the page at the moment, it can return
41 * -EAGAIN. The VM interprets this as a temporary migration failure and
42 * will retry it later. Any other error value is a permanent migration
43 * failure and migration will not be retried.
44 * The driver shouldn't touch the @src->lru field while in the
45 * migrate_page() function. It may write to @dst->lru.
46 *
47 * @putback_page:
48 * If migration fails on the isolated page, the VM informs the driver
49 * that the page is no longer a candidate for migration by calling
50 * this function. The driver should put the isolated page back into
51 * its own data structure.
52 */
53struct movable_operations {
54 bool (*isolate_page)(struct page *, isolate_mode_t);
55 int (*migrate_page)(struct page *dst, struct page *src,
56 enum migrate_mode);
57 void (*putback_page)(struct page *);
58};
59
60/* Defined in mm/debug.c: */
61extern const char *migrate_reason_names[MR_TYPES];
62
63#ifdef CONFIG_MIGRATION
64
65void putback_movable_pages(struct list_head *l);
66int migrate_folio(struct address_space *mapping, struct folio *dst,
67 struct folio *src, enum migrate_mode mode);
68int migrate_pages(struct list_head *l, new_folio_t new, free_folio_t free,
69 unsigned long private, enum migrate_mode mode, int reason,
70 unsigned int *ret_succeeded);
71struct folio *alloc_migration_target(struct folio *src, unsigned long private);
72bool isolate_movable_ops_page(struct page *page, isolate_mode_t mode);
73bool isolate_folio_to_list(struct folio *folio, struct list_head *list);
74
75int migrate_huge_page_move_mapping(struct address_space *mapping,
76 struct folio *dst, struct folio *src);
77void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)
78 __releases(ptl);
79void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
80int folio_migrate_mapping(struct address_space *mapping,
81 struct folio *newfolio, struct folio *folio, int extra_count);
82int set_movable_ops(const struct movable_operations *ops, enum pagetype type);
83
84#else
85
86static inline void putback_movable_pages(struct list_head *l) {}
87static inline int migrate_pages(struct list_head *l, new_folio_t new,
88 free_folio_t free, unsigned long private,
89 enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
90 { return -ENOSYS; }
91static inline struct folio *alloc_migration_target(struct folio *src,
92 unsigned long private)
93 { return NULL; }
94static inline bool isolate_movable_ops_page(struct page *page, isolate_mode_t mode)
95 { return false; }
96static inline bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
97 { return false; }
98
99static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
100 struct folio *dst, struct folio *src)
101{
102 return -ENOSYS;
103}
104static inline int set_movable_ops(const struct movable_operations *ops, enum pagetype type)
105{
106 return -ENOSYS;
107}
108
109#endif /* CONFIG_MIGRATION */
110
111#ifdef CONFIG_NUMA_BALANCING
112int migrate_misplaced_folio_prepare(struct folio *folio,
113 struct vm_area_struct *vma, int node);
114int migrate_misplaced_folio(struct folio *folio, int node);
115#else
116static inline int migrate_misplaced_folio_prepare(struct folio *folio,
117 struct vm_area_struct *vma, int node)
118{
119 return -EAGAIN; /* can't migrate now */
120}
121static inline int migrate_misplaced_folio(struct folio *folio, int node)
122{
123 return -EAGAIN; /* can't migrate now */
124}
125#endif /* CONFIG_NUMA_BALANCING */
126
127#ifdef CONFIG_MIGRATION
128
129/*
130 * Watch out for PAE architecture, which has an unsigned long, and might not
131 * have enough bits to store all physical address and flags. So far we have
132 * enough room for all our flags.
133 */
134#define MIGRATE_PFN_VALID (1UL << 0)
135#define MIGRATE_PFN_MIGRATE (1UL << 1)
136#define MIGRATE_PFN_WRITE (1UL << 3)
137#define MIGRATE_PFN_SHIFT 6
138
139static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
140{
141 if (!(mpfn & MIGRATE_PFN_VALID))
142 return NULL;
143 return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT);
144}
145
146static inline unsigned long migrate_pfn(unsigned long pfn)
147{
148 return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
149}
150
151enum migrate_vma_direction {
152 MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
153 MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
154 MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2,
155};
156
157struct migrate_vma {
158 struct vm_area_struct *vma;
159 /*
160 * Both src and dst array must be big enough for
161 * (end - start) >> PAGE_SHIFT entries.
162 *
163 * The src array must not be modified by the caller after
164 * migrate_vma_setup(), and must not change the dst array after
165 * migrate_vma_pages() returns.
166 */
167 unsigned long *dst;
168 unsigned long *src;
169 unsigned long cpages;
170 unsigned long npages;
171 unsigned long start;
172 unsigned long end;
173
174 /*
175 * Set to the owner value also stored in page_pgmap(page)->owner
176 * for migrating out of device private memory. The flags also need to
177 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE.
178 * The caller should always set this field when using mmu notifier
179 * callbacks to avoid device MMU invalidations for device private
180 * pages that are not being migrated.
181 */
182 void *pgmap_owner;
183 unsigned long flags;
184
185 /*
186 * Set to vmf->page if this is being called to migrate a page as part of
187 * a migrate_to_ram() callback.
188 */
189 struct page *fault_page;
190};
191
192int migrate_vma_setup(struct migrate_vma *args);
193void migrate_vma_pages(struct migrate_vma *migrate);
194void migrate_vma_finalize(struct migrate_vma *migrate);
195int migrate_device_range(unsigned long *src_pfns, unsigned long start,
196 unsigned long npages);
197int migrate_device_pfns(unsigned long *src_pfns, unsigned long npages);
198void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns,
199 unsigned long npages);
200void migrate_device_finalize(unsigned long *src_pfns,
201 unsigned long *dst_pfns, unsigned long npages);
202
203#endif /* CONFIG_MIGRATION */
204
205#endif /* _LINUX_MIGRATE_H */