diff options
Diffstat (limited to 'include/linux/migrate.h')
| -rw-r--r-- | include/linux/migrate.h | 120 |
1 files changed, 19 insertions, 101 deletions
diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 7f04754c7f2b..72120061b7d4 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -166,8 +166,6 @@ static inline int migrate_misplaced_transhuge_page(struct mm_struct *mm, #define MIGRATE_PFN_MIGRATE (1UL << 1) #define MIGRATE_PFN_LOCKED (1UL << 2) #define MIGRATE_PFN_WRITE (1UL << 3) -#define MIGRATE_PFN_DEVICE (1UL << 4) -#define MIGRATE_PFN_ERROR (1UL << 5) #define MIGRATE_PFN_SHIFT 6 static inline struct page *migrate_pfn_to_page(unsigned long mpfn) @@ -182,107 +180,27 @@ static inline unsigned long migrate_pfn(unsigned long pfn) return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; } -/* - * struct migrate_vma_ops - migrate operation callback - * - * @alloc_and_copy: alloc destination memory and copy source memory to it - * @finalize_and_map: allow caller to map the successfully migrated pages - * - * - * The alloc_and_copy() callback happens once all source pages have been locked, - * unmapped and checked (checked whether pinned or not). All pages that can be - * migrated will have an entry in the src array set with the pfn value of the - * page and with the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set (other - * flags might be set but should be ignored by the callback). - * - * The alloc_and_copy() callback can then allocate destination memory and copy - * source memory to it for all those entries (ie with MIGRATE_PFN_VALID and - * MIGRATE_PFN_MIGRATE flag set). Once these are allocated and copied, the - * callback must update each corresponding entry in the dst array with the pfn - * value of the destination page and with the MIGRATE_PFN_VALID and - * MIGRATE_PFN_LOCKED flags set (destination pages must have their struct pages - * locked, via lock_page()). - * - * At this point the alloc_and_copy() callback is done and returns. - * - * Note that the callback does not have to migrate all the pages that are - * marked with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration - * from device memory to system memory (ie the MIGRATE_PFN_DEVICE flag is also - * set in the src array entry). If the device driver cannot migrate a device - * page back to system memory, then it must set the corresponding dst array - * entry to MIGRATE_PFN_ERROR. This will trigger a SIGBUS if CPU tries to - * access any of the virtual addresses originally backed by this page. Because - * a SIGBUS is such a severe result for the userspace process, the device - * driver should avoid setting MIGRATE_PFN_ERROR unless it is really in an - * unrecoverable state. - * - * For empty entry inside CPU page table (pte_none() or pmd_none() is true) we - * do set MIGRATE_PFN_MIGRATE flag inside the corresponding source array thus - * allowing device driver to allocate device memory for those unback virtual - * address. For this the device driver simply have to allocate device memory - * and properly set the destination entry like for regular migration. Note that - * this can still fails and thus inside the device driver must check if the - * migration was successful for those entry inside the finalize_and_map() - * callback just like for regular migration. - * - * THE alloc_and_copy() CALLBACK MUST NOT CHANGE ANY OF THE SRC ARRAY ENTRIES - * OR BAD THINGS WILL HAPPEN ! - * - * - * The finalize_and_map() callback happens after struct page migration from - * source to destination (destination struct pages are the struct pages for the - * memory allocated by the alloc_and_copy() callback). Migration can fail, and - * thus the finalize_and_map() allows the driver to inspect which pages were - * successfully migrated, and which were not. Successfully migrated pages will - * have the MIGRATE_PFN_MIGRATE flag set for their src array entry. - * - * It is safe to update device page table from within the finalize_and_map() - * callback because both destination and source page are still locked, and the - * mmap_sem is held in read mode (hence no one can unmap the range being - * migrated). - * - * Once callback is done cleaning up things and updating its page table (if it - * chose to do so, this is not an obligation) then it returns. At this point, - * the HMM core will finish up the final steps, and the migration is complete. - * - * THE finalize_and_map() CALLBACK MUST NOT CHANGE ANY OF THE SRC OR DST ARRAY - * ENTRIES OR BAD THINGS WILL HAPPEN ! - */ -struct migrate_vma_ops { - void (*alloc_and_copy)(struct vm_area_struct *vma, - const unsigned long *src, - unsigned long *dst, - unsigned long start, - unsigned long end, - void *private); - void (*finalize_and_map)(struct vm_area_struct *vma, - const unsigned long *src, - const unsigned long *dst, - unsigned long start, - unsigned long end, - void *private); +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; }; -#if defined(CONFIG_MIGRATE_VMA_HELPER) -int migrate_vma(const struct migrate_vma_ops *ops, - struct vm_area_struct *vma, - unsigned long start, - unsigned long end, - unsigned long *src, - unsigned long *dst, - void *private); -#else -static inline int migrate_vma(const struct migrate_vma_ops *ops, - struct vm_area_struct *vma, - unsigned long start, - unsigned long end, - unsigned long *src, - unsigned long *dst, - void *private) -{ - return -EINVAL; -} -#endif /* IS_ENABLED(CONFIG_MIGRATE_VMA_HELPER) */ +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 */ |