With revision 09c2f95ad404, 64bit writes in _base_writeq() were rewritten to use __raw_writeq() instad of writeq(). This introduced a bug apparent on powerpc64 systems such as the Raptor Talos II that causes the HBA to drop from the PCIe bus under heavy load and being reinitialized after a couple of seconds. The issue has been reported on the linux-scsi mailing list: * https://www.spinics.net/lists/linux-scsi/msg126099.html * https://marc.info/?l=linux-scsi&m=154413193422697&w=2 It can easily be triggered on affacted systems by using something like fio --name=random-write --iodepth=4 --rw=randwrite --bs=4k --direct=0 \ --size=128M --numjobs=64 --end_fsync=1 fio --name=random-write --iodepth=4 --rw=randwrite --bs=64k --direct=0 \ --size=128M --numjobs=64 --end_fsync=1 a couple of times. In my case I tested it on both a ZFS raidz2 and a btrfs raid6 using LSI 9300-8i and 9400-8i controllers. The fix consists in resembling the write ordering of writeq() by adding a mandatory write memory barrier before device access and a compiler barrier afterwards. The additional MMIO barrier is superfluous. Signed-off-by: Stephan Günther <moepi@xxxxxxxxx> Reported-by: Matt Corallo <linux@xxxxxxxxxxx> --- drivers/scsi/mpt3sas/mpt3sas_base.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c index 2500377d0723..bfd826deabbe 100644 --- a/drivers/scsi/mpt3sas/mpt3sas_base.c +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c @@ -3319,8 +3319,9 @@ _base_mpi_ep_writeq(__u64 b, volatile void __iomem *addr, static inline void _base_writeq(__u64 b, volatile void __iomem *addr, spinlock_t *writeq_lock) { + wmb(); __raw_writeq(b, addr); - mmiowb(); + barrier(); } #else static inline void -- 2.19.2
