1 files changed, 214 insertions, 18 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 38e7cad782f4..55dbc45880c6 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 +139,17 @@ 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);
+        if (PageHuge(new))
+                pte = pte_mkhuge(pte);
         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 +292,59 @@ 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 +788,92 @@ 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 +938,52 @@ 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