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

scsi: libsas: align sata_device's rps_resp on a cacheline

to the 4.4-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-libsas-align-sata_device-s-rps_resp-on-a-cacheline.patch and it can be found in the queue-4.4 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 c2e8fbf908afd81ad502b567a6639598f92c9b9d Mon Sep 17 00:00:00 2001

From: Huacai Chen chenhc@lemote.com Date: Tue, 21 Nov 2017 14:23:39 +0100 Subject: scsi: libsas: align sata_device's rps_resp on a cacheline

From: Huacai Chen chenhc@lemote.com

commit c2e8fbf908afd81ad502b567a6639598f92c9b9d upstream.

The rps_resp buffer in ata_device is a DMA target, but it isn't explicitly cacheline aligned. Due to this, adjacent fields can be overwritten with stale data from memory on non-coherent architectures. As a result, the kernel is sometimes unable to communicate with an SATA device behind a SAS expander.

Fix this by ensuring that the rps_resp buffer is cacheline aligned.

This issue is similar to that fixed by Commit 84bda12af31f93 ("libata: align ap->sector_buf") and Commit 4ee34ea3a12396f35b26 ("libata: Align ata_device's id on a cacheline").

Signed-off-by: Huacai Chen chenhc@lemote.com 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

--- include/scsi/libsas.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/scsi/libsas.h +++ b/include/scsi/libsas.h @@ -165,11 +165,11 @@ struct expander_device {

struct sata_device { unsigned int class; - struct smp_resp rps_resp; /* report_phy_sata_resp */ u8 port_no; /* port number, if this is a PM (Port) */

struct ata_port *ap; struct ata_host ata_host; + struct smp_resp rps_resp ____cacheline_aligned; /* report_phy_sata_resp */ u8 fis[ATA_RESP_FIS_SIZE]; };

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

queue-4.4/scsi-use-dma_get_cache_alignment-as-minimum-dma-alignment.patch queue-4.4/scsi-libsas-align-sata_device-s-rps_resp-on-a-cacheline.patch