[PATCH v2 2/2] zram: fix uninitialized ZRAM not releasing backing device

[Kairui Song <ryncsn@gmail.com>]

From: Kairui Song <kasong@tencent.com>

Setting backing device is done before ZRAM initialization.
If we set the backing device, then remove the ZRAM module without
initializing the device, the backing device reference will be leaked
and the device will be hold forever.

Fix this by always reset the ZRAM fully on rmmod or reset store.

Fixes: 013bf95a83ec ("zram: add interface to specif backing device")
Reported-by: Desheng Wu <deshengwu@tencent.com>
Suggested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: stable@vger.kernel.org
---
 drivers/block/zram/zram_drv.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index e86cc3d2f4d2..45df5eeabc5e 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1444,12 +1444,16 @@ static void zram_meta_free(struct zram *zram, u64 disksize)
 	size_t num_pages = disksize >> PAGE_SHIFT;
 	size_t index;
 
+	if (!zram->table)
+		return;
+
 	/* Free all pages that are still in this zram device */
 	for (index = 0; index < num_pages; index++)
 		zram_free_page(zram, index);
 
 	zs_destroy_pool(zram->mem_pool);
 	vfree(zram->table);
+	zram->table = NULL;
 }
 
 static bool zram_meta_alloc(struct zram *zram, u64 disksize)
@@ -2326,11 +2330,6 @@ static void zram_reset_device(struct zram *zram)
 
 	zram->limit_pages = 0;
 
-	if (!init_done(zram)) {
-		up_write(&zram->init_lock);
-		return;
-	}
-
 	set_capacity_and_notify(zram->disk, 0);
 	part_stat_set_all(zram->disk->part0, 0);
 
-- 
2.47.1