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Diffstat (limited to 'block/blk-map.c')
-rw-r--r--block/blk-map.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/block/blk-map.c b/block/blk-map.c
index 813011ef827..ddd96fb11a7 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -269,6 +269,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
int reading = rq_data_dir(rq) == READ;
int do_copy = 0;
struct bio *bio;
+ unsigned long stack_mask = ~(THREAD_SIZE - 1);
if (len > (q->max_hw_sectors << 9))
return -EINVAL;
@@ -279,6 +280,10 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
alignment = queue_dma_alignment(q) | q->dma_pad_mask;
do_copy = ((kaddr & alignment) || (len & alignment));
+ if (!((kaddr & stack_mask) ^
+ ((unsigned long)current->stack & stack_mask)))
+ do_copy = 1;
+
if (do_copy)
bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
else