1 files changed, 24 insertions, 26 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index ccf8966caf6f..ac6f4939bb59 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -100,7 +100,7 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	/*
 	 * Check PageMovable before holding a PG_lock because page's owner
 	 * assumes anybody doesn't touch PG_lock of newly allocated page
-	 * so unconditionally grapping the lock ruins page's owner side.
+	 * so unconditionally grabbing the lock ruins page's owner side.
 	 */
 	if (unlikely(!__PageMovable(page)))
 		goto out_putpage;
@@ -374,7 +374,7 @@ unlock:
 }
 #endif
 
-static int expected_page_refs(struct page *page)
+static int expected_page_refs(struct address_space *mapping, struct page *page)
 {
 	int expected_count = 1;
 
@@ -384,7 +384,7 @@ static int expected_page_refs(struct page *page)
 	 */
 	expected_count += is_device_private_page(page);
 	expected_count += is_device_public_page(page);
-	if (page_mapping(page))
+	if (mapping)
 		expected_count += hpage_nr_pages(page) + page_has_private(page);
 
 	return expected_count;
@@ -405,7 +405,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
 	XA_STATE(xas, &mapping->i_pages, page_index(page));
 	struct zone *oldzone, *newzone;
 	int dirty;
-	int expected_count = expected_page_refs(page) + extra_count;
+	int expected_count = expected_page_refs(mapping, page) + extra_count;
 
 	if (!mapping) {
 		/* Anonymous page without mapping */
@@ -709,7 +709,6 @@ static bool buffer_migrate_lock_buffers(struct buffer_head *head,
 	/* Simple case, sync compaction */
 	if (mode != MIGRATE_ASYNC) {
 		do {
-			get_bh(bh);
 			lock_buffer(bh);
 			bh = bh->b_this_page;
 
@@ -720,18 +719,15 @@ static bool buffer_migrate_lock_buffers(struct buffer_head *head,
 
 	/* async case, we cannot block on lock_buffer so use trylock_buffer */
 	do {
-		get_bh(bh);
 		if (!trylock_buffer(bh)) {
 			/*
 			 * We failed to lock the buffer and cannot stall in
 			 * async migration. Release the taken locks
 			 */
 			struct buffer_head *failed_bh = bh;
-			put_bh(failed_bh);
 			bh = head;
 			while (bh != failed_bh) {
 				unlock_buffer(bh);
-				put_bh(bh);
 				bh = bh->b_this_page;
 			}
 			return false;
@@ -754,7 +750,7 @@ static int __buffer_migrate_page(struct address_space *mapping,
 		return migrate_page(mapping, newpage, page, mode);
 
 	/* Check whether page does not have extra refs before we do more work */
-	expected_count = expected_page_refs(page);
+	expected_count = expected_page_refs(mapping, page);
 	if (page_count(page) != expected_count)
 		return -EAGAIN;
 
@@ -818,7 +814,6 @@ unlock_buffers:
 	bh = head;
 	do {
 		unlock_buffer(bh);
-		put_bh(bh);
 		bh = bh->b_this_page;
 
 	} while (bh != head);
@@ -916,7 +911,7 @@ static int fallback_migrate_page(struct address_space *mapping,
 	 */
 	if (page_has_private(page) &&
 	    !try_to_release_page(page, GFP_KERNEL))
-		return -EAGAIN;
+		return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
 
 	return migrate_page(mapping, newpage, page, mode);
 }
@@ -1135,10 +1130,13 @@ out:
 	 * If migration is successful, decrease refcount of the newpage
 	 * which will not free the page because new page owner increased
 	 * refcounter. As well, if it is LRU page, add the page to LRU
-	 * list in here.
+	 * list in here. Use the old state of the isolated source page to
+	 * determine if we migrated a LRU page. newpage was already unlocked
+	 * and possibly modified by its owner - don't rely on the page
+	 * state.
 	 */
 	if (rc == MIGRATEPAGE_SUCCESS) {
-		if (unlikely(__PageMovable(newpage)))
+		if (unlikely(!is_lru))
 			put_page(newpage);
 		else
 			putback_lru_page(newpage);
@@ -1289,7 +1287,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	struct anon_vma *anon_vma = NULL;
 
 	/*
-	 * Movability of hugepages depends on architectures and hugepage size.
+	 * Migratability of hugepages depends on architectures and their size.
 	 * This check is necessary because some callers of hugepage migration
 	 * like soft offline and memory hotremove don't walk through page
 	 * tables or check whether the hugepage is pmd-based or not before
@@ -1317,6 +1315,16 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 		lock_page(hpage);
 	}
 
+	/*
+	 * Check for pages which are in the process of being freed.  Without
+	 * page_mapping() set, hugetlbfs specific move page routine will not
+	 * be called and we could leak usage counts for subpools.
+	 */
+	if (page_private(hpage) && !page_mapping(hpage)) {
+		rc = -EBUSY;
+		goto out_unlock;
+	}
+
 	if (PageAnon(hpage))
 		anon_vma = page_get_anon_vma(hpage);
 
@@ -1324,19 +1332,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 		goto put_anon;
 
 	if (page_mapped(hpage)) {
-		struct address_space *mapping = page_mapping(hpage);
-
-		/*
-		 * try_to_unmap could potentially call huge_pmd_unshare.
-		 * Because of this, take semaphore in write mode here and
-		 * set TTU_RMAP_LOCKED to let lower levels know we have
-		 * taken the lock.
-		 */
-		i_mmap_lock_write(mapping);
 		try_to_unmap(hpage,
-			TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS|
-			TTU_RMAP_LOCKED);
-		i_mmap_unlock_write(mapping);
+			TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
 		page_was_mapped = 1;
 	}
 
@@ -1358,6 +1355,7 @@ put_anon:
 		put_new_page = NULL;
 	}
 
+out_unlock:
 	unlock_page(hpage);
 out:
 	if (rc != -EAGAIN)