mmc: need to zero sglist on init

Otherwise we could have junk in the sg fields, fooling
the sg chaining into thinking ->page is valid.

Acked-by: Pierre Ossman <drzeus@drzeus.cx>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

drivers/mmc/card/queue.c

@@ -153,14 +153,14 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock
 			blk_queue_max_hw_segments(mq->queue, bouncesz / 512);
 			blk_queue_max_segment_size(mq->queue, bouncesz);
 
-			mq->sg = kmalloc(sizeof(struct scatterlist),
+			mq->sg = kzalloc(sizeof(struct scatterlist),
 				GFP_KERNEL);
 			if (!mq->sg) {
 				ret = -ENOMEM;
 				goto cleanup_queue;
 			}
 
-			mq->bounce_sg = kmalloc(sizeof(struct scatterlist) *
+			mq->bounce_sg = kzalloc(sizeof(struct scatterlist) *
 				bouncesz / 512, GFP_KERNEL);
 			if (!mq->bounce_sg) {
 				ret = -ENOMEM;
@@ -177,7 +177,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock
 		blk_queue_max_hw_segments(mq->queue, host->max_hw_segs);
 		blk_queue_max_segment_size(mq->queue, host->max_seg_size);
 
-		mq->sg = kmalloc(sizeof(struct scatterlist) *
+		mq->sg = kzalloc(sizeof(struct scatterlist) *
 			host->max_phys_segs, GFP_KERNEL);
 		if (!mq->sg) {
 			ret = -ENOMEM;