293 lines
10 KiB
C
293 lines
10 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_MIGRATE_H
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#define _LINUX_MIGRATE_H
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#include <linux/mm.h>
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#include <linux/mempolicy.h>
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#include <linux/migrate_mode.h>
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#include <linux/hugetlb.h>
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typedef struct page *new_page_t(struct page *page, unsigned long private,
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int **reason);
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typedef void free_page_t(struct page *page, unsigned long private);
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/*
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* Return values from addresss_space_operations.migratepage():
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* - negative errno on page migration failure;
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* - zero on page migration success;
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*/
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#define MIGRATEPAGE_SUCCESS 0
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enum migrate_reason {
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MR_COMPACTION,
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MR_MEMORY_FAILURE,
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MR_MEMORY_HOTPLUG,
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MR_SYSCALL, /* also applies to cpusets */
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MR_MEMPOLICY_MBIND,
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MR_NUMA_MISPLACED,
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MR_CMA,
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MR_TYPES
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};
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/* In mm/debug.c; also keep sync with include/trace/events/migrate.h */
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extern char *migrate_reason_names[MR_TYPES];
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static inline struct page *new_page_nodemask(struct page *page,
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int preferred_nid, nodemask_t *nodemask)
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{
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gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL;
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unsigned int order = 0;
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struct page *new_page = NULL;
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if (PageHuge(page))
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return alloc_huge_page_nodemask(page_hstate(compound_head(page)),
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preferred_nid, nodemask);
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if (thp_migration_supported() && PageTransHuge(page)) {
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order = HPAGE_PMD_ORDER;
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gfp_mask |= GFP_TRANSHUGE;
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}
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if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
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gfp_mask |= __GFP_HIGHMEM;
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new_page = __alloc_pages_nodemask(gfp_mask, order,
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preferred_nid, nodemask);
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if (new_page && PageTransHuge(page))
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prep_transhuge_page(new_page);
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return new_page;
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}
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#ifdef CONFIG_MIGRATION
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extern void putback_movable_pages(struct list_head *l);
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extern int migrate_page(struct address_space *mapping,
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struct page *newpage, struct page *page,
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enum migrate_mode mode);
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extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
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unsigned long private, enum migrate_mode mode, int reason);
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extern int isolate_movable_page(struct page *page, isolate_mode_t mode);
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extern void putback_movable_page(struct page *page);
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extern int migrate_prep(void);
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extern int migrate_prep_local(void);
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extern void migrate_page_states(struct page *newpage, struct page *page);
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extern void migrate_page_copy(struct page *newpage, struct page *page);
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extern int migrate_huge_page_move_mapping(struct address_space *mapping,
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struct page *newpage, struct page *page);
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extern int migrate_page_move_mapping(struct address_space *mapping,
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struct page *newpage, struct page *page,
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struct buffer_head *head, enum migrate_mode mode,
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int extra_count);
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#else
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static inline void putback_movable_pages(struct list_head *l) {}
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static inline int migrate_pages(struct list_head *l, new_page_t new,
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free_page_t free, unsigned long private, enum migrate_mode mode,
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int reason)
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{ return -ENOSYS; }
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static inline int isolate_movable_page(struct page *page, isolate_mode_t mode)
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{ return -EBUSY; }
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static inline int migrate_prep(void) { return -ENOSYS; }
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static inline int migrate_prep_local(void) { return -ENOSYS; }
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static inline void migrate_page_states(struct page *newpage, struct page *page)
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{
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}
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static inline void migrate_page_copy(struct page *newpage,
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struct page *page) {}
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static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
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struct page *newpage, struct page *page)
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{
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return -ENOSYS;
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}
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#endif /* CONFIG_MIGRATION */
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#ifdef CONFIG_COMPACTION
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extern int PageMovable(struct page *page);
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extern void __SetPageMovable(struct page *page, struct address_space *mapping);
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extern void __ClearPageMovable(struct page *page);
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#else
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static inline int PageMovable(struct page *page) { return 0; };
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static inline void __SetPageMovable(struct page *page,
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struct address_space *mapping)
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{
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}
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static inline void __ClearPageMovable(struct page *page)
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{
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}
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#endif
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#ifdef CONFIG_NUMA_BALANCING
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extern bool pmd_trans_migrating(pmd_t pmd);
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extern int migrate_misplaced_page(struct page *page,
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struct vm_area_struct *vma, int node);
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#else
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static inline bool pmd_trans_migrating(pmd_t pmd)
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{
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return false;
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}
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static inline int migrate_misplaced_page(struct page *page,
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struct vm_area_struct *vma, int node)
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{
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return -EAGAIN; /* can't migrate now */
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}
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#endif /* CONFIG_NUMA_BALANCING */
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#if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
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extern int migrate_misplaced_transhuge_page(struct mm_struct *mm,
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struct vm_area_struct *vma,
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pmd_t *pmd, pmd_t entry,
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unsigned long address,
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struct page *page, int node);
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#else
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static inline int migrate_misplaced_transhuge_page(struct mm_struct *mm,
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struct vm_area_struct *vma,
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pmd_t *pmd, pmd_t entry,
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unsigned long address,
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struct page *page, int node)
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{
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return -EAGAIN;
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}
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#endif /* CONFIG_NUMA_BALANCING && CONFIG_TRANSPARENT_HUGEPAGE*/
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#ifdef CONFIG_MIGRATION
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/*
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* Watch out for PAE architecture, which has an unsigned long, and might not
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* have enough bits to store all physical address and flags. So far we have
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* enough room for all our flags.
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*/
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#define MIGRATE_PFN_VALID (1UL << 0)
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#define MIGRATE_PFN_MIGRATE (1UL << 1)
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#define MIGRATE_PFN_LOCKED (1UL << 2)
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#define MIGRATE_PFN_WRITE (1UL << 3)
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#define MIGRATE_PFN_DEVICE (1UL << 4)
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#define MIGRATE_PFN_ERROR (1UL << 5)
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#define MIGRATE_PFN_SHIFT 6
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static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
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{
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if (!(mpfn & MIGRATE_PFN_VALID))
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return NULL;
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return pfn_to_page(mpfn >> MIGRATE_PFN_SHIFT);
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}
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static inline unsigned long migrate_pfn(unsigned long pfn)
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{
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return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
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}
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/*
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* struct migrate_vma_ops - migrate operation callback
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*
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* @alloc_and_copy: alloc destination memory and copy source memory to it
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* @finalize_and_map: allow caller to map the successfully migrated pages
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*
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*
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* The alloc_and_copy() callback happens once all source pages have been locked,
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* unmapped and checked (checked whether pinned or not). All pages that can be
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* migrated will have an entry in the src array set with the pfn value of the
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* page and with the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set (other
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* flags might be set but should be ignored by the callback).
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*
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* The alloc_and_copy() callback can then allocate destination memory and copy
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* source memory to it for all those entries (ie with MIGRATE_PFN_VALID and
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* MIGRATE_PFN_MIGRATE flag set). Once these are allocated and copied, the
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* callback must update each corresponding entry in the dst array with the pfn
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* value of the destination page and with the MIGRATE_PFN_VALID and
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* MIGRATE_PFN_LOCKED flags set (destination pages must have their struct pages
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* locked, via lock_page()).
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*
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* At this point the alloc_and_copy() callback is done and returns.
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*
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* Note that the callback does not have to migrate all the pages that are
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* marked with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration
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* from device memory to system memory (ie the MIGRATE_PFN_DEVICE flag is also
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* set in the src array entry). If the device driver cannot migrate a device
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* page back to system memory, then it must set the corresponding dst array
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* entry to MIGRATE_PFN_ERROR. This will trigger a SIGBUS if CPU tries to
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* access any of the virtual addresses originally backed by this page. Because
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* a SIGBUS is such a severe result for the userspace process, the device
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* driver should avoid setting MIGRATE_PFN_ERROR unless it is really in an
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* unrecoverable state.
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*
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* For empty entry inside CPU page table (pte_none() or pmd_none() is true) we
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* do set MIGRATE_PFN_MIGRATE flag inside the corresponding source array thus
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* allowing device driver to allocate device memory for those unback virtual
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* address. For this the device driver simply have to allocate device memory
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* and properly set the destination entry like for regular migration. Note that
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* this can still fails and thus inside the device driver must check if the
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* migration was successful for those entry inside the finalize_and_map()
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* callback just like for regular migration.
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*
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* THE alloc_and_copy() CALLBACK MUST NOT CHANGE ANY OF THE SRC ARRAY ENTRIES
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* OR BAD THINGS WILL HAPPEN !
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*
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*
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* The finalize_and_map() callback happens after struct page migration from
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* source to destination (destination struct pages are the struct pages for the
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* memory allocated by the alloc_and_copy() callback). Migration can fail, and
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* thus the finalize_and_map() allows the driver to inspect which pages were
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* successfully migrated, and which were not. Successfully migrated pages will
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* have the MIGRATE_PFN_MIGRATE flag set for their src array entry.
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*
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* It is safe to update device page table from within the finalize_and_map()
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* callback because both destination and source page are still locked, and the
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* mmap_sem is held in read mode (hence no one can unmap the range being
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* migrated).
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*
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* Once callback is done cleaning up things and updating its page table (if it
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* chose to do so, this is not an obligation) then it returns. At this point,
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* the HMM core will finish up the final steps, and the migration is complete.
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*
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* THE finalize_and_map() CALLBACK MUST NOT CHANGE ANY OF THE SRC OR DST ARRAY
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* ENTRIES OR BAD THINGS WILL HAPPEN !
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*/
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struct migrate_vma_ops {
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void (*alloc_and_copy)(struct vm_area_struct *vma,
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const unsigned long *src,
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unsigned long *dst,
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unsigned long start,
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unsigned long end,
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void *private);
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void (*finalize_and_map)(struct vm_area_struct *vma,
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const unsigned long *src,
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const unsigned long *dst,
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unsigned long start,
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unsigned long end,
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void *private);
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};
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#if defined(CONFIG_MIGRATE_VMA_HELPER)
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int migrate_vma(const struct migrate_vma_ops *ops,
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struct vm_area_struct *vma,
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unsigned long start,
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unsigned long end,
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unsigned long *src,
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unsigned long *dst,
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void *private);
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#else
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static inline int migrate_vma(const struct migrate_vma_ops *ops,
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struct vm_area_struct *vma,
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unsigned long start,
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unsigned long end,
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unsigned long *src,
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unsigned long *dst,
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void *private)
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{
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return -EINVAL;
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}
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#endif /* IS_ENABLED(CONFIG_MIGRATE_VMA_HELPER) */
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#endif /* CONFIG_MIGRATION */
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#endif /* _LINUX_MIGRATE_H */
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