3.2.100-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Huacai Chen <chenhc@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- include/scsi/libsas.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/include/scsi/libsas.h +++ b/include/scsi/libsas.h @@ -163,7 +163,6 @@ enum ata_command_set { struct sata_device { enum ata_command_set command_set; - struct smp_resp rps_resp; /* report_phy_sata_resp */ __le16 *identify_device; __le16 *identify_packet_device; @@ -172,6 +171,7 @@ struct sata_device { 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]; };