zram: do not leak page on writeback_store error path

Ensure the page used for local object data is freed on error out path.

Link: https://lkml.kernel.org/r/20250303022425.285971-19-senozhatsky@chromium.org
Fixes: 330edc2bc059 (zram: rework writeback target selection strategy)
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index e50a5a216974a2d67fe09a82f6ddc719d492fa68..fda7d8624889f65a8d7e5ae7bcdfa718f87ba33c 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -787,7 +787,7 @@ static ssize_t writeback_store(struct device *dev,
        unsigned long index = 0;
        struct bio bio;
        struct bio_vec bio_vec;
-       struct page *page;
+       struct page *page = NULL;
        ssize_t ret = len;
        int mode, err;
        unsigned long blk_idx = 0;
@@ -929,8 +929,10 @@ next:
 
        if (blk_idx)
                free_block_bdev(zram, blk_idx);
-       __free_page(page);
+
 release_init_lock:
+       if (page)
+               __free_page(page);
        release_pp_ctl(zram, ctl);
        atomic_set(&zram->pp_in_progress, 0);
        up_read(&zram->init_lock);