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From: "Zhang, Jerry (Junwei)" <Jerry.Zhang-5C7GfCeVMHo@public.gmane.org>
To: "Felix Kuehling" <felix.kuehling-5C7GfCeVMHo@public.gmane.org>,
	"amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org"
	<amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>,
	"Christian König" <christian.koenig-5C7GfCeVMHo@public.gmane.org>
Subject: Re: When to kmap PT BOs?
Date: Thu, 30 Aug 2018 12:49:25 +0800	[thread overview]
Message-ID: <5B877755.3090402@amd.com> (raw)
In-Reply-To: <7a9aa339-e771-c667-4eb8-6f30c7c37c15-5C7GfCeVMHo@public.gmane.org>

On 08/30/2018 06:30 AM, Felix Kuehling wrote:
> Hi,
>
> Currently PT BOs are kmapped in amdgpu_vm_update_directories. That
> means, to avoid kernel oopses after page table evictions, I need to call
> amdgpu_vm_update_directories before calling amdgpu_vm_bo_update.
>
> But amdgpu_vm_bo_update can also move PTs on the vm->relocated list
> during huge page handling. That means I also need to call
> amdgpu_vm_update_directories after amdgpu_vm_bo_update.

Not very familiar with huge page handling.

But from code, maybe we can kmap the PTE entry right here.
Then it will update current non-huge page PTE later in amdgpu_vm_update_ptes().

Regards,
Jerry

>
> I think a better solution is to move kmapping out of
> amdgpu_vm_update_directories. But I'm not sure what's the right place
> for it. Any suggestions? For a quick fix for kernel oopses after page
> table evictions in the ROCm 1.9 release I'll call
> amdgpu_vm_update_directories twice. If there are no new entries on the
> vm->relocated lists, the second call won't add much overhead anyway.
>
> Thanks,
>    Felix
>
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  parent reply	other threads:[~2018-08-30  4:49 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-29 22:30 When to kmap PT BOs? Felix Kuehling
     [not found] ` <7a9aa339-e771-c667-4eb8-6f30c7c37c15-5C7GfCeVMHo@public.gmane.org>
2018-08-30  4:49   ` Zhang, Jerry (Junwei) [this message]
2018-08-30  6:50   ` Christian König

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