zram_drv: allow reclaim on bio_alloc

The read_from_bdev_async is not called on atomic context.  So GFP_NOIO
is available rather than GFP_ATOMIC.  If there were reclaimable pages
with GFP_NOIO, we can avoid allocation failure and page fault failure.

Link: https://lkml.kernel.org/r/20210908005241.28062-1-jaewon31.kim@samsung.com
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Reported-by: Yong-Taek Lee <ytk.lee@samsung.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/zram/zram_drv.c

@@ -587,7 +587,7 @@ static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec,
 {
 	struct bio *bio;
 
-	bio = bio_alloc(GFP_ATOMIC, 1);
+	bio = bio_alloc(GFP_NOIO, 1);
 	if (!bio)
 		return -ENOMEM;