1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MIGRATE_H
3 #define _LINUX_MIGRATE_H
6 #include <linux/mempolicy.h>
7 #include <linux/migrate_mode.h>
8 #include <linux/hugetlb.h>
10 typedef struct page
*new_page_t(struct page
*page
, unsigned long private);
11 typedef void free_page_t(struct page
*page
, unsigned long private);
14 * Return values from addresss_space_operations.migratepage():
15 * - negative errno on page migration failure;
16 * - zero on page migration success;
18 #define MIGRATEPAGE_SUCCESS 0
24 MR_SYSCALL
, /* also applies to cpusets */
31 /* In mm/debug.c; also keep sync with include/trace/events/migrate.h */
32 extern char *migrate_reason_names
[MR_TYPES
];
34 static inline struct page
*new_page_nodemask(struct page
*page
,
35 int preferred_nid
, nodemask_t
*nodemask
)
37 gfp_t gfp_mask
= GFP_USER
| __GFP_MOVABLE
| __GFP_RETRY_MAYFAIL
;
38 unsigned int order
= 0;
39 struct page
*new_page
= NULL
;
42 return alloc_huge_page_nodemask(page_hstate(compound_head(page
)),
43 preferred_nid
, nodemask
);
45 if (PageTransHuge(page
)) {
46 gfp_mask
|= GFP_TRANSHUGE
;
47 order
= HPAGE_PMD_ORDER
;
50 if (PageHighMem(page
) || (zone_idx(page_zone(page
)) == ZONE_MOVABLE
))
51 gfp_mask
|= __GFP_HIGHMEM
;
53 new_page
= __alloc_pages_nodemask(gfp_mask
, order
,
54 preferred_nid
, nodemask
);
56 if (new_page
&& PageTransHuge(new_page
))
57 prep_transhuge_page(new_page
);
62 #ifdef CONFIG_MIGRATION
64 extern void putback_movable_pages(struct list_head
*l
);
65 extern int migrate_page(struct address_space
*mapping
,
66 struct page
*newpage
, struct page
*page
,
67 enum migrate_mode mode
);
68 extern int migrate_pages(struct list_head
*l
, new_page_t
new, free_page_t free
,
69 unsigned long private, enum migrate_mode mode
, int reason
);
70 extern int isolate_movable_page(struct page
*page
, isolate_mode_t mode
);
71 extern void putback_movable_page(struct page
*page
);
73 extern int migrate_prep(void);
74 extern int migrate_prep_local(void);
75 extern void migrate_page_states(struct page
*newpage
, struct page
*page
);
76 extern void migrate_page_copy(struct page
*newpage
, struct page
*page
);
77 extern int migrate_huge_page_move_mapping(struct address_space
*mapping
,
78 struct page
*newpage
, struct page
*page
);
79 extern int migrate_page_move_mapping(struct address_space
*mapping
,
80 struct page
*newpage
, struct page
*page
,
81 struct buffer_head
*head
, enum migrate_mode mode
,
85 static inline void putback_movable_pages(struct list_head
*l
) {}
86 static inline int migrate_pages(struct list_head
*l
, new_page_t
new,
87 free_page_t free
, unsigned long private, enum migrate_mode mode
,
90 static inline int isolate_movable_page(struct page
*page
, isolate_mode_t mode
)
93 static inline int migrate_prep(void) { return -ENOSYS
; }
94 static inline int migrate_prep_local(void) { return -ENOSYS
; }
96 static inline void migrate_page_states(struct page
*newpage
, struct page
*page
)
100 static inline void migrate_page_copy(struct page
*newpage
,
101 struct page
*page
) {}
103 static inline int migrate_huge_page_move_mapping(struct address_space
*mapping
,
104 struct page
*newpage
, struct page
*page
)
109 #endif /* CONFIG_MIGRATION */
111 #ifdef CONFIG_COMPACTION
112 extern int PageMovable(struct page
*page
);
113 extern void __SetPageMovable(struct page
*page
, struct address_space
*mapping
);
114 extern void __ClearPageMovable(struct page
*page
);
116 static inline int PageMovable(struct page
*page
) { return 0; };
117 static inline void __SetPageMovable(struct page
*page
,
118 struct address_space
*mapping
)
121 static inline void __ClearPageMovable(struct page
*page
)
126 #ifdef CONFIG_NUMA_BALANCING
127 extern bool pmd_trans_migrating(pmd_t pmd
);
128 extern int migrate_misplaced_page(struct page
*page
,
129 struct vm_area_struct
*vma
, int node
);
131 static inline bool pmd_trans_migrating(pmd_t pmd
)
135 static inline int migrate_misplaced_page(struct page
*page
,
136 struct vm_area_struct
*vma
, int node
)
138 return -EAGAIN
; /* can't migrate now */
140 #endif /* CONFIG_NUMA_BALANCING */
142 #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
143 extern int migrate_misplaced_transhuge_page(struct mm_struct
*mm
,
144 struct vm_area_struct
*vma
,
145 pmd_t
*pmd
, pmd_t entry
,
146 unsigned long address
,
147 struct page
*page
, int node
);
149 static inline int migrate_misplaced_transhuge_page(struct mm_struct
*mm
,
150 struct vm_area_struct
*vma
,
151 pmd_t
*pmd
, pmd_t entry
,
152 unsigned long address
,
153 struct page
*page
, int node
)
157 #endif /* CONFIG_NUMA_BALANCING && CONFIG_TRANSPARENT_HUGEPAGE*/
160 #ifdef CONFIG_MIGRATION
163 * Watch out for PAE architecture, which has an unsigned long, and might not
164 * have enough bits to store all physical address and flags. So far we have
165 * enough room for all our flags.
167 #define MIGRATE_PFN_VALID (1UL << 0)
168 #define MIGRATE_PFN_MIGRATE (1UL << 1)
169 #define MIGRATE_PFN_LOCKED (1UL << 2)
170 #define MIGRATE_PFN_WRITE (1UL << 3)
171 #define MIGRATE_PFN_DEVICE (1UL << 4)
172 #define MIGRATE_PFN_ERROR (1UL << 5)
173 #define MIGRATE_PFN_SHIFT 6
175 static inline struct page
*migrate_pfn_to_page(unsigned long mpfn
)
177 if (!(mpfn
& MIGRATE_PFN_VALID
))
179 return pfn_to_page(mpfn
>> MIGRATE_PFN_SHIFT
);
182 static inline unsigned long migrate_pfn(unsigned long pfn
)
184 return (pfn
<< MIGRATE_PFN_SHIFT
) | MIGRATE_PFN_VALID
;
188 * struct migrate_vma_ops - migrate operation callback
190 * @alloc_and_copy: alloc destination memory and copy source memory to it
191 * @finalize_and_map: allow caller to map the successfully migrated pages
194 * The alloc_and_copy() callback happens once all source pages have been locked,
195 * unmapped and checked (checked whether pinned or not). All pages that can be
196 * migrated will have an entry in the src array set with the pfn value of the
197 * page and with the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set (other
198 * flags might be set but should be ignored by the callback).
200 * The alloc_and_copy() callback can then allocate destination memory and copy
201 * source memory to it for all those entries (ie with MIGRATE_PFN_VALID and
202 * MIGRATE_PFN_MIGRATE flag set). Once these are allocated and copied, the
203 * callback must update each corresponding entry in the dst array with the pfn
204 * value of the destination page and with the MIGRATE_PFN_VALID and
205 * MIGRATE_PFN_LOCKED flags set (destination pages must have their struct pages
206 * locked, via lock_page()).
208 * At this point the alloc_and_copy() callback is done and returns.
210 * Note that the callback does not have to migrate all the pages that are
211 * marked with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration
212 * from device memory to system memory (ie the MIGRATE_PFN_DEVICE flag is also
213 * set in the src array entry). If the device driver cannot migrate a device
214 * page back to system memory, then it must set the corresponding dst array
215 * entry to MIGRATE_PFN_ERROR. This will trigger a SIGBUS if CPU tries to
216 * access any of the virtual addresses originally backed by this page. Because
217 * a SIGBUS is such a severe result for the userspace process, the device
218 * driver should avoid setting MIGRATE_PFN_ERROR unless it is really in an
219 * unrecoverable state.
221 * For empty entry inside CPU page table (pte_none() or pmd_none() is true) we
222 * do set MIGRATE_PFN_MIGRATE flag inside the corresponding source array thus
223 * allowing device driver to allocate device memory for those unback virtual
224 * address. For this the device driver simply have to allocate device memory
225 * and properly set the destination entry like for regular migration. Note that
226 * this can still fails and thus inside the device driver must check if the
227 * migration was successful for those entry inside the finalize_and_map()
228 * callback just like for regular migration.
230 * THE alloc_and_copy() CALLBACK MUST NOT CHANGE ANY OF THE SRC ARRAY ENTRIES
231 * OR BAD THINGS WILL HAPPEN !
234 * The finalize_and_map() callback happens after struct page migration from
235 * source to destination (destination struct pages are the struct pages for the
236 * memory allocated by the alloc_and_copy() callback). Migration can fail, and
237 * thus the finalize_and_map() allows the driver to inspect which pages were
238 * successfully migrated, and which were not. Successfully migrated pages will
239 * have the MIGRATE_PFN_MIGRATE flag set for their src array entry.
241 * It is safe to update device page table from within the finalize_and_map()
242 * callback because both destination and source page are still locked, and the
243 * mmap_sem is held in read mode (hence no one can unmap the range being
246 * Once callback is done cleaning up things and updating its page table (if it
247 * chose to do so, this is not an obligation) then it returns. At this point,
248 * the HMM core will finish up the final steps, and the migration is complete.
250 * THE finalize_and_map() CALLBACK MUST NOT CHANGE ANY OF THE SRC OR DST ARRAY
251 * ENTRIES OR BAD THINGS WILL HAPPEN !
253 struct migrate_vma_ops
{
254 void (*alloc_and_copy
)(struct vm_area_struct
*vma
,
255 const unsigned long *src
,
260 void (*finalize_and_map
)(struct vm_area_struct
*vma
,
261 const unsigned long *src
,
262 const unsigned long *dst
,
268 #if defined(CONFIG_MIGRATE_VMA_HELPER)
269 int migrate_vma(const struct migrate_vma_ops
*ops
,
270 struct vm_area_struct
*vma
,
277 static inline int migrate_vma(const struct migrate_vma_ops
*ops
,
278 struct vm_area_struct
*vma
,
287 #endif /* IS_ENABLED(CONFIG_MIGRATE_VMA_HELPER) */
289 #endif /* CONFIG_MIGRATION */
291 #endif /* _LINUX_MIGRATE_H */