X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=mm%2Fzsmalloc.c;h=439deb8decbcc3f1707bf0f4e42416bf6d0d09c8;hb=8ad43539c638a719b9a3d7503a75a2ecad304431;hp=68e8831068f4b52bb792fb0d5bc29dbee996039d;hpb=de5540965853e514a85d3b775e9049deb85a2ff3;p=platform%2Fkernel%2Flinux-rpi.git

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 68e8831..439deb8 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1743,11 +1743,40 @@ static enum fullness_group putback_zspage(struct size_class *class,
  */
 static void lock_zspage(struct zspage *zspage)
 {
-	struct page *page = get_first_page(zspage);
+	struct page *curr_page, *page;
 
-	do {
-		lock_page(page);
-	} while ((page = get_next_page(page)) != NULL);
+	/*
+	 * Pages we haven't locked yet can be migrated off the list while we're
+	 * trying to lock them, so we need to be careful and only attempt to
+	 * lock each page under migrate_read_lock(). Otherwise, the page we lock
+	 * may no longer belong to the zspage. This means that we may wait for
+	 * the wrong page to unlock, so we must take a reference to the page
+	 * prior to waiting for it to unlock outside migrate_read_lock().
+	 */
+	while (1) {
+		migrate_read_lock(zspage);
+		page = get_first_page(zspage);
+		if (trylock_page(page))
+			break;
+		get_page(page);
+		migrate_read_unlock(zspage);
+		wait_on_page_locked(page);
+		put_page(page);
+	}
+
+	curr_page = page;
+	while ((page = get_next_page(curr_page))) {
+		if (trylock_page(page)) {
+			curr_page = page;
+		} else {
+			get_page(page);
+			migrate_read_unlock(zspage);
+			wait_on_page_locked(page);
+			put_page(page);
+			migrate_read_lock(zspage);
+		}
+	}
+	migrate_read_unlock(zspage);
 }
 
 static int zs_init_fs_context(struct fs_context *fc)
@@ -1830,10 +1859,11 @@ static inline void zs_pool_dec_isolated(struct zs_pool *pool)
 	VM_BUG_ON(atomic_long_read(&pool->isolated_pages) <= 0);
 	atomic_long_dec(&pool->isolated_pages);
 	/*
-	 * There's no possibility of racing, since wait_for_isolated_drain()
-	 * checks the isolated count under &class->lock after enqueuing
-	 * on migration_wait.
+	 * Checking pool->destroying must happen after atomic_long_dec()
+	 * for pool->isolated_pages above. Paired with the smp_mb() in
+	 * zs_unregister_migration().
 	 */
+	smp_mb__after_atomic();
 	if (atomic_long_read(&pool->isolated_pages) == 0 && pool->destroying)
 		wake_up_all(&pool->migration_wait);
 }