Writeback loop can run for quite a while (depending on
wb device performance, compression algorithm and the
number of entries we writeback), so we need to do
cond_resched() there, similarly to what we do in
recompress loop.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 drivers/block/zram/zram_drv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 3dee026988dc..882a32d46a75 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -883,6 +883,8 @@ static ssize_t writeback_store(struct device *dev,
 next:
 		zram_slot_unlock(zram, index);
 		release_pp_slot(zram, pps);
+
+		cond_resched();
 	}
 
 	if (blk_idx)
-- 
2.47.0.371.ga323438b13-goog