This is a note to let you know that I've just added the patch titled

scsi: use dma_get_cache_alignment() as minimum DMA alignment

to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: scsi-use-dma_get_cache_alignment-as-minimum-dma-alignment.patch and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 90addc6b3c9cda0146fbd62a08e234c2b224a80c Mon Sep 17 00:00:00 2001

From: Huacai Chen chenhc@lemote.com Date: Tue, 21 Nov 2017 14:23:38 +0100 Subject: scsi: use dma_get_cache_alignment() as minimum DMA alignment

From: Huacai Chen chenhc@lemote.com

commit 90addc6b3c9cda0146fbd62a08e234c2b224a80c upstream.

In non-coherent DMA mode, kernel uses cache flushing operations to maintain I/O coherency, so scsi's block queue should be aligned to the value returned by dma_get_cache_alignment(). Otherwise, If a DMA buffer and a kernel structure share a same cache line, and if the kernel structure has dirty data, cache_invalidate (no writeback) will cause data corruption.

Signed-off-by: Huacai Chen chenhc@lemote.com [hch: rebased and updated the comment and changelog] Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/scsi/scsi_lib.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2028,11 +2028,13 @@ static void __scsi_init_queue(struct Scs q->limits.cluster = 0;

/* - * set a reasonable default alignment on word boundaries: the - * host and device may alter it using - * blk_queue_update_dma_alignment() later. + * Set a reasonable default alignment: The larger of 32-byte (dword), + * which is a common minimum for HBAs, and the minimum DMA alignment, + * which is set by the platform. + * + * Devices that require a bigger alignment can increase it later. */ - blk_queue_dma_alignment(q, 0x03); + blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1); }

struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,

Patches currently in stable-queue which might be from chenhc@lemote.com are

queue-3.18/scsi-use-dma_get_cache_alignment-as-minimum-dma-alignment.patch