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From: "Christian König" <christian.koenig@amd.com>
To: Junrui Luo <moonafterrain@outlook.com>
Cc: Alex Deucher <alexander.deucher@amd.com>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Jammy Zhou <Jammy.Zhou@amd.com>,
	Madhav Chauhan <madhav.chauhan@amd.com>,
	Felix Kuehling <Felix.Kuehling@amd.com>,
	"amd-gfx@lists.freedesktop.org" <amd-gfx@lists.freedesktop.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Yuhao Jiang <danisjiang@gmail.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH 2/3] drm/amdgpu: fix VM update overrun on non-4K page kernels
Date: Mon, 10 Aug 2026 15:07:11 +0200	[thread overview]
Message-ID: <8a1d942a-2b2d-4525-83d1-3c434c0a3679@amd.com> (raw)
In-Reply-To: <B5DD8C80-AB11-4D23-A602-EBEACD6EE04A@outlook.com>



On 8/8/26 19:03, Junrui Luo wrote:
> On Thu, Aug 06, 2026 at 01:59:52PM +0200, Christian König wrote:
>>
>> That check is clearly not correct. The pages_addr must be fully consumed, otherwise we run into major problems later on.
> 
> Is that an invariant today?  num_entries <= AMDGPU_GPU_PAGES_IN_CPU_PAGE
> skips the scan and is used as it is, so on a 64K page kernel a 4K mapping
> maps a single GPU page and pages_addr is not consumed in whole CPU pages
> there either.

Exactly that doesn't work. On a 64K page kernel mappings *must* be 64K as well.

> So what should the code do for a mapping whose size is not a multiple of
> AMDGPU_GPU_PAGES_IN_CPU_PAGE?  Could you sketch what you have in mind?

That case simply can't happen for user space allocations in the first place.

Regards,
Christian.

> 
> Thanks,
> Junrui Luo


  reply	other threads:[~2026-08-10 13:07 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-06  4:45 [PATCH 0/3] drm/amdgpu: three independent fixes in the CS and VM paths Junrui Luo via B4 Relay
2026-08-06  4:45 ` [PATCH 1/3] drm/amdgpu: disallow multiple FENCE chunks in one submit Junrui Luo via B4 Relay
2026-08-06 11:54   ` Christian König
2026-08-06 20:25     ` Alex Deucher
2026-08-06  4:45 ` [PATCH 2/3] drm/amdgpu: fix VM update overrun on non-4K page kernels Junrui Luo via B4 Relay
2026-08-06 11:59   ` Christian König
2026-08-08 17:03     ` Junrui Luo
2026-08-10 13:07       ` Christian König [this message]
2026-08-06  4:45 ` [PATCH 3/3] drm/amdgpu: add the BO-va mapping offset when kmapping an IB Junrui Luo via B4 Relay
2026-08-06 12:05   ` Christian König

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