diff options
Diffstat (limited to 'mm/migrate.c')
| -rw-r--r-- | mm/migrate.c | 234 |
1 files changed, 216 insertions, 18 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 38e7cad782f4..f8c9bccf2520 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -32,6 +32,7 @@ #include <linux/security.h> #include <linux/memcontrol.h> #include <linux/syscalls.h> +#include <linux/hugetlb.h> #include <linux/gfp.h> #include "internal.h" @@ -95,26 +96,34 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, pte_t *ptep, pte; spinlock_t *ptl; - pgd = pgd_offset(mm, addr); - if (!pgd_present(*pgd)) - goto out; + if (unlikely(PageHuge(new))) { + ptep = huge_pte_offset(mm, addr); + if (!ptep) + goto out; + ptl = &mm->page_table_lock; + } else { + pgd = pgd_offset(mm, addr); + if (!pgd_present(*pgd)) + goto out; - pud = pud_offset(pgd, addr); - if (!pud_present(*pud)) - goto out; + pud = pud_offset(pgd, addr); + if (!pud_present(*pud)) + goto out; - pmd = pmd_offset(pud, addr); - if (!pmd_present(*pmd)) - goto out; + pmd = pmd_offset(pud, addr); + if (!pmd_present(*pmd)) + goto out; - ptep = pte_offset_map(pmd, addr); + ptep = pte_offset_map(pmd, addr); - if (!is_swap_pte(*ptep)) { - pte_unmap(ptep); - goto out; - } + if (!is_swap_pte(*ptep)) { + pte_unmap(ptep); + goto out; + } + + ptl = pte_lockptr(mm, pmd); + } - ptl = pte_lockptr(mm, pmd); spin_lock(ptl); pte = *ptep; if (!is_swap_pte(pte)) @@ -130,10 +139,19 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); if (is_write_migration_entry(entry)) pte = pte_mkwrite(pte); +#ifdef CONFIG_HUGETLB_PAGE + if (PageHuge(new)) + pte = pte_mkhuge(pte); +#endif flush_cache_page(vma, addr, pte_pfn(pte)); set_pte_at(mm, addr, ptep, pte); - if (PageAnon(new)) + if (PageHuge(new)) { + if (PageAnon(new)) + hugepage_add_anon_rmap(new, vma, addr); + else + page_dup_rmap(new); + } else if (PageAnon(new)) page_add_anon_rmap(new, vma, addr); else page_add_file_rmap(new); @@ -276,11 +294,59 @@ static int migrate_page_move_mapping(struct address_space *mapping, } /* + * The expected number of remaining references is the same as that + * of migrate_page_move_mapping(). + */ +int migrate_huge_page_move_mapping(struct address_space *mapping, + struct page *newpage, struct page *page) +{ + int expected_count; + void **pslot; + + if (!mapping) { + if (page_count(page) != 1) + return -EAGAIN; + return 0; + } + + spin_lock_irq(&mapping->tree_lock); + + pslot = radix_tree_lookup_slot(&mapping->page_tree, + page_index(page)); + + expected_count = 2 + page_has_private(page); + if (page_count(page) != expected_count || + (struct page *)radix_tree_deref_slot(pslot) != page) { + spin_unlock_irq(&mapping->tree_lock); + return -EAGAIN; + } + + if (!page_freeze_refs(page, expected_count)) { + spin_unlock_irq(&mapping->tree_lock); + return -EAGAIN; + } + + get_page(newpage); + + radix_tree_replace_slot(pslot, newpage); + + page_unfreeze_refs(page, expected_count); + + __put_page(page); + + spin_unlock_irq(&mapping->tree_lock); + return 0; +} + +/* * Copy the page to its new location */ -static void migrate_page_copy(struct page *newpage, struct page *page) +void migrate_page_copy(struct page *newpage, struct page *page) { - copy_highpage(newpage, page); + if (PageHuge(page)) + copy_huge_page(newpage, page); + else + copy_highpage(newpage, page); if (PageError(page)) SetPageError(newpage); @@ -724,6 +790,92 @@ move_newpage: } /* + * Counterpart of unmap_and_move_page() for hugepage migration. + * + * This function doesn't wait the completion of hugepage I/O + * because there is no race between I/O and migration for hugepage. + * Note that currently hugepage I/O occurs only in direct I/O + * where no lock is held and PG_writeback is irrelevant, + * and writeback status of all subpages are counted in the reference + * count of the head page (i.e. if all subpages of a 2MB hugepage are + * under direct I/O, the reference of the head page is 512 and a bit more.) + * This means that when we try to migrate hugepage whose subpages are + * doing direct I/O, some references remain after try_to_unmap() and + * hugepage migration fails without data corruption. + * + * There is also no race when direct I/O is issued on the page under migration, + * because then pte is replaced with migration swap entry and direct I/O code + * will wait in the page fault for migration to complete. + */ +static int unmap_and_move_huge_page(new_page_t get_new_page, + unsigned long private, struct page *hpage, + int force, int offlining) +{ + int rc = 0; + int *result = NULL; + struct page *new_hpage = get_new_page(hpage, private, &result); + int rcu_locked = 0; + struct anon_vma *anon_vma = NULL; + + if (!new_hpage) + return -ENOMEM; + + rc = -EAGAIN; + + if (!trylock_page(hpage)) { + if (!force) + goto out; + lock_page(hpage); + } + + if (PageAnon(hpage)) { + rcu_read_lock(); + rcu_locked = 1; + + if (page_mapped(hpage)) { + anon_vma = page_anon_vma(hpage); + atomic_inc(&anon_vma->external_refcount); + } + } + + try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); + + if (!page_mapped(hpage)) + rc = move_to_new_page(new_hpage, hpage, 1); + + if (rc) + remove_migration_ptes(hpage, hpage); + + if (anon_vma && atomic_dec_and_lock(&anon_vma->external_refcount, + &anon_vma->lock)) { + int empty = list_empty(&anon_vma->head); + spin_unlock(&anon_vma->lock); + if (empty) + anon_vma_free(anon_vma); + } + + if (rcu_locked) + rcu_read_unlock(); +out: + unlock_page(hpage); + + if (rc != -EAGAIN) { + list_del(&hpage->lru); + put_page(hpage); + } + + put_page(new_hpage); + + if (result) { + if (rc) + *result = rc; + else + *result = page_to_nid(new_hpage); + } + return rc; +} + +/* * migrate_pages * * The function takes one list of pages to migrate and a function @@ -788,6 +940,52 @@ out: return nr_failed + retry; } +int migrate_huge_pages(struct list_head *from, + new_page_t get_new_page, unsigned long private, int offlining) +{ + int retry = 1; + int nr_failed = 0; + int pass = 0; + struct page *page; + struct page *page2; + int rc; + + for (pass = 0; pass < 10 && retry; pass++) { + retry = 0; + + list_for_each_entry_safe(page, page2, from, lru) { + cond_resched(); + + rc = unmap_and_move_huge_page(get_new_page, + private, page, pass > 2, offlining); + + switch(rc) { + case -ENOMEM: + goto out; + case -EAGAIN: + retry++; + break; + case 0: + break; + default: + /* Permanent failure */ + nr_failed++; + break; + } + } + } + rc = 0; +out: + + list_for_each_entry_safe(page, page2, from, lru) + put_page(page); + + if (rc) + return rc; + + return nr_failed + retry; +} + #ifdef CONFIG_NUMA /* * Move a list of individual pages |