1 files changed, 46 insertions, 87 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 7dbcb22..efddbf0 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -21,6 +21,7 @@
 #include <linux/mm_inline.h>
 #include <linux/nsproxy.h>
 #include <linux/pagevec.h>
+#include <linux/ksm.h>
 #include <linux/rmap.h>
 #include <linux/topology.h>
 #include <linux/cpu.h>
@@ -78,8 +79,8 @@ int putback_lru_pages(struct list_head *l)
 /*
  * Restore a potential migration pte to a working pte entry
  */
-static void remove_migration_pte(struct vm_area_struct *vma,
-		struct page *old, struct page *new)
+static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
+				 unsigned long addr, void *old)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	swp_entry_t entry;
@@ -88,40 +89,37 @@ static void remove_migration_pte(struct vm_area_struct *vma,
  	pmd_t *pmd;
 	pte_t *ptep, pte;
  	spinlock_t *ptl;
-	unsigned long addr = page_address_in_vma(new, vma);
-
-	if (addr == -EFAULT)
-		return;
 
  	pgd = pgd_offset(mm, addr);
 	if (!pgd_present(*pgd))
-                return;
+		goto out;
 
 	pud = pud_offset(pgd, addr);
 	if (!pud_present(*pud))
-                return;
+		goto out;
 
 	pmd = pmd_offset(pud, addr);
 	if (!pmd_present(*pmd))
-		return;
+		goto out;
 
 	ptep = pte_offset_map(pmd, addr);
 
 	if (!is_swap_pte(*ptep)) {
 		pte_unmap(ptep);
- 		return;
+		goto out;
  	}
 
  	ptl = pte_lockptr(mm, pmd);
  	spin_lock(ptl);
 	pte = *ptep;
 	if (!is_swap_pte(pte))
-		goto out;
+		goto unlock;
 
 	entry = pte_to_swp_entry(pte);
 
-	if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
-		goto out;
+	if (!is_migration_entry(entry) ||
+	    migration_entry_to_page(entry) != old)
+		goto unlock;
 
 	get_page(new);
 	pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
@@ -137,58 +135,10 @@ static void remove_migration_pte(struct vm_area_struct *vma,
 
 	/* No need to invalidate - it was non-present before */
 	update_mmu_cache(vma, addr, pte);
-
-out:
+unlock:
 	pte_unmap_unlock(ptep, ptl);
-}
-
-/*
- * Note that remove_file_migration_ptes will only work on regular mappings,
- * Nonlinear mappings do not use migration entries.
- */
-static void remove_file_migration_ptes(struct page *old, struct page *new)
-{
-	struct vm_area_struct *vma;
-	struct address_space *mapping = new->mapping;
-	struct prio_tree_iter iter;
-	pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
-
-	if (!mapping)
-		return;
-
-	spin_lock(&mapping->i_mmap_lock);
-
-	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
-		remove_migration_pte(vma, old, new);
-
-	spin_unlock(&mapping->i_mmap_lock);
-}
-
-/*
- * Must hold mmap_sem lock on at least one of the vmas containing
- * the page so that the anon_vma cannot vanish.
- */
-static void remove_anon_migration_ptes(struct page *old, struct page *new)
-{
-	struct anon_vma *anon_vma;
-	struct vm_area_struct *vma;
-	unsigned long mapping;
-
-	mapping = (unsigned long)new->mapping;
-
-	if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
-		return;
-
-	/*
-	 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
-	 */
-	anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
-	spin_lock(&anon_vma->lock);
-
-	list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
-		remove_migration_pte(vma, old, new);
-
-	spin_unlock(&anon_vma->lock);
+out:
+	return SWAP_AGAIN;
 }
 
 /*
@@ -197,10 +147,7 @@ static void remove_anon_migration_ptes(struct page *old, struct page *new)
  */
 static void remove_migration_ptes(struct page *old, struct page *new)
 {
-	if (PageAnon(new))
-		remove_anon_migration_ptes(old, new);
-	else
-		remove_file_migration_ptes(old, new);
+	rmap_walk(new, remove_migration_pte, old);
 }
 
 /*
@@ -341,8 +288,8 @@ static void migrate_page_copy(struct page *newpage, struct page *page)
 	if (TestClearPageActive(page)) {
 		VM_BUG_ON(PageUnevictable(page));
 		SetPageActive(newpage);
-	} else
-		unevictable_migrate_page(newpage, page);
+	} else if (TestClearPageUnevictable(page))
+		SetPageUnevictable(newpage);
 	if (PageChecked(page))
 		SetPageChecked(newpage);
 	if (PageMappedToDisk(page))
@@ -361,6 +308,7 @@ static void migrate_page_copy(struct page *newpage, struct page *page)
  	}
 
 	mlock_migrate_page(newpage, page);
+	ksm_migrate_page(newpage, page);
 
 	ClearPageSwapCache(page);
 	ClearPagePrivate(page);
@@ -580,9 +528,9 @@ static int move_to_new_page(struct page *newpage, struct page *page)
 	else
 		rc = fallback_migrate_page(mapping, newpage, page);
 
-	if (!rc) {
+	if (!rc)
 		remove_migration_ptes(page, newpage);
-	} else
+	else
 		newpage->mapping = NULL;
 
 	unlock_page(newpage);
@@ -595,7 +543,7 @@ static int move_to_new_page(struct page *newpage, struct page *page)
  * to the newly allocated page in newpage.
  */
 static int unmap_and_move(new_page_t get_new_page, unsigned long private,
-			struct page *page, int force)
+			struct page *page, int force, int offlining)
 {
 	int rc = 0;
 	int *result = NULL;
@@ -621,6 +569,20 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
 		lock_page(page);
 	}
 
+	/*
+	 * Only memory hotplug's offline_pages() caller has locked out KSM,
+	 * and can safely migrate a KSM page.  The other cases have skipped
+	 * PageKsm along with PageReserved - but it is only now when we have
+	 * the page lock that we can be certain it will not go KSM beneath us
+	 * (KSM will not upgrade a page from PageAnon to PageKsm when it sees
+	 * its pagecount raised, but only here do we take the page lock which
+	 * serializes that).
+	 */
+	if (PageKsm(page) && !offlining) {
+		rc = -EBUSY;
+		goto unlock;
+	}
+
 	/* charge against new page */
 	charge = mem_cgroup_prepare_migration(page, &mem);
 	if (charge == -ENOMEM) {
@@ -737,7 +699,7 @@ move_newpage:
  * Return: Number of pages not migrated or error code.
  */
 int migrate_pages(struct list_head *from,
-		new_page_t get_new_page, unsigned long private)
+		new_page_t get_new_page, unsigned long private, int offlining)
 {
 	int retry = 1;
 	int nr_failed = 0;
@@ -746,13 +708,6 @@ int migrate_pages(struct list_head *from,
 	struct page *page2;
 	int swapwrite = current->flags & PF_SWAPWRITE;
 	int rc;
-	unsigned long flags;
-
-	local_irq_save(flags);
-	list_for_each_entry(page, from, lru)
-		__inc_zone_page_state(page, NR_ISOLATED_ANON +
-				page_is_file_cache(page));
-	local_irq_restore(flags);
 
 	if (!swapwrite)
 		current->flags |= PF_SWAPWRITE;
@@ -764,7 +719,7 @@ int migrate_pages(struct list_head *from,
 			cond_resched();
 
 			rc = unmap_and_move(get_new_page, private,
-						page, pass > 2);
+						page, pass > 2, offlining);
 
 			switch(rc) {
 			case -ENOMEM:
@@ -860,7 +815,8 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
 		if (!page)
 			goto set_status;
 
-		if (PageReserved(page))		/* Check for zero page */
+		/* Use PageReserved to check for zero page */
+		if (PageReserved(page) || PageKsm(page))
 			goto put_and_set;
 
 		pp->page = page;
@@ -878,8 +834,11 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
 			goto put_and_set;
 
 		err = isolate_lru_page(page);
-		if (!err)
+		if (!err) {
 			list_add_tail(&page->lru, &pagelist);
+			inc_zone_page_state(page, NR_ISOLATED_ANON +
+					    page_is_file_cache(page));
+		}
 put_and_set:
 		/*
 		 * Either remove the duplicate refcount from
@@ -894,7 +853,7 @@ set_status:
 	err = 0;
 	if (!list_empty(&pagelist))
 		err = migrate_pages(&pagelist, new_page_node,
-				(unsigned long)pm);
+				(unsigned long)pm, 0);
 
 	up_read(&mm->mmap_sem);
 	return err;
@@ -1015,7 +974,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
 
 		err = -ENOENT;
 		/* Use PageReserved to check for zero page */
-		if (!page || PageReserved(page))
+		if (!page || PageReserved(page) || PageKsm(page))
 			goto set_status;
 
 		err = page_to_nid(page);
@@ -1044,7 +1003,7 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
 	int err;
 
 	for (i = 0; i < nr_pages; i += chunk_nr) {
-		if (chunk_nr + i > nr_pages)
+		if (chunk_nr > nr_pages - i)
 			chunk_nr = nr_pages - i;
 
 		err = copy_from_user(chunk_pages, &pages[i],