The patch titled
block: blk_rq_map_kern uses the bounce buffers for stack buffers
has been added to the -mm tree. Its filename is
block-blk_rq_map_kern-uses-the-bounce-buffers-for-stack-buffers.patch
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------------------------------------------------------
Subject: block: blk_rq_map_kern uses the bounce buffers for stack buffers
From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
blk_rq_map_kern is used for kernel internal I/Os. Some callers use
this function with stack buffers but DMA to/from the stack buffers
leads to memory corruption on a non-coherent platform.
This patch make blk_rq_map_kern uses the bounce buffers if a caller
passes a stack buffer (on the all platforms for simplicity).
Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Tejun Heo <htejun@xxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
block/blk-map.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN block/blk-map.c~block-blk_rq_map_kern-uses-the-bounce-buffers-for-stack-buffers block/blk-map.c
--- a/block/blk-map.c~block-blk_rq_map_kern-uses-the-bounce-buffers-for-stack-buffers
+++ a/block/blk-map.c
@@ -268,6 +268,7 @@ int blk_rq_map_kern(struct request_queue
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;
@@ -278,6 +279,10 @@ int blk_rq_map_kern(struct request_queue
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
_
Patches currently in -mm which might be from fujita.tomonori@xxxxxxxxxxxxx are
linux-next.patch
block-add-blk_queue_update_dma_pad.patch
ide-use-the-dma-safe-check-for-req_type_ata_pc.patch
block-blk_rq_map_kern-uses-the-bounce-buffers-for-stack-buffers.patch
ide-avoid-dma-on-the-stack-for-req_type_ata_pc.patch
scsi-sr-avoids-useless-buffer-allocation.patch
cdrom-revert-commit-22a9189-cdrom-use-kmalloced-buffers-instead-of-buffers-on-stack.patch
dma-mapping-add-the-device-argument-to-dma_mapping_error.patch
dma-mapping-add-the-device-argument-to-dma_mapping_error-sge-fix.patch
dma-mapping-add-the-device-argument-to-dma_mapping_error-svc_rdma-fix.patch
dma-mapping-add-the-device-argument-to-dma_mapping_error-bnx2x.patch
dma-mapping-add-the-device-argument-to-dma_mapping_error-sparc32.patch
dma-mapping-x86-per-device-dma_mapping_ops-support.patch
dma-mapping-x86-per-device-dma_mapping_ops-support-fix.patch
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