linux-kernel - Re: [PATCH v2 0/5] *** GPU Direct RDMA (P2P DMA) for Device Private Pages ***

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Message-ID: <20250723084413.GO402218@unreal>
Date: Wed, 23 Jul 2025 11:44:13 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Jason Gunthorpe <jgg@...pe.ca>
Cc: Yonatan Maman <ymaman@...dia.com>,
	Jérôme Glisse <jglisse@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Lyude Paul <lyude@...hat.com>, Danilo Krummrich <dakr@...nel.org>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Alistair Popple <apopple@...dia.com>,
	Ben Skeggs <bskeggs@...dia.com>,
	Michael Guralnik <michaelgur@...dia.com>,
	Or Har-Toov <ohartoov@...dia.com>,
	Daisuke Matsuda <dskmtsd@...il.com>, Shay Drory <shayd@...dia.com>,
	linux-mm@...ck.org, linux-rdma@...r.kernel.org,
	dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/5] *** GPU Direct RDMA (P2P DMA) for Device Private
 Pages ***

On Wed, Jul 23, 2025 at 01:03:47AM -0300, Jason Gunthorpe wrote:
> On Mon, Jul 21, 2025 at 09:49:04AM +0300, Leon Romanovsky wrote:
> > > In fact, hmm_range_fault doesn't have information about the destination
> > > device that will perform the DMA mapping.
> > 
> > So probably you need to teach HMM to perform page_faults on specific device.
> 
> That isn't how the HMM side is supposed to work, this API is just
> giving the one and only P2P page that is backing the device private.

I know, but somehow you need to say: "please give me p2p pages for
specific device and not random device in the system as it is now".
This is what is missing from my PoV.

Thanks