Hi Robin/Ashok,

Find attached trace of DMA write error. I had a look on trace but didn't find anything suspicious.

Let me know if you need more trace.

Regards

Harsh Jain


On 29-09-2017 21:48, Casey Leedom wrote:
> | From: Harsh Jain <Harsh-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org>
> | Sent: Friday, September 29, 2017 1:14:45 AM
> |     
> | Robin,
> | 
> | I tried running patch on our test setup.
> | 
> | With "intel_iommu=on" : I can see single occurrence of DMAR Write failure
> | on perf traffic with 10 thread.
> | 
> | [  749.616480] perf: interrupt took too long (3203 > 3202), lowering kernel.perf_event_max_sample_rate to 62000
> | [  852.500671] DMAR: DRHD: handling fault status reg 2
> | [  852.506039] DMAR: [DMA Write] Request device [02:00.4] fault addr ef919000 [fault reason 05] PTE Write access is not set
> | [root@heptagon linux_t4_build]# cat /proc/cmdline
> | BOOT_IMAGE=/vmlinuz-4.9.51+ root=UUID=ccbb7f18-b3f0-43df-89de-07521e9c02fe ro intel_iommu=on crashkernel=auto rhgb quiet rhgb quiet console=ttyS0,115200, console=tty0 LANG=en_US.UTF-8
>
> Harsh. Can you provide the debugging information for that one DMA FAILURE
> trace?  It May be yet another corner case in __domain_mapping() or a
> different path.
>
> | With intel_iommu=sp_off : It works fine for more than 30 minutes without
> | any issues.
>
> I think that even without Robin's patch using intel_iommu=sp_off worked
> without errors, right?
>
> Casey