From: Alistair Popple <apopple@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: <linux-mm@kvack.org>, <nouveau@lists.freedesktop.org>,
<bskeggs@redhat.com>, <akpm@linux-foundation.org>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<kvm-ppc@vger.kernel.org>, <dri-devel@lists.freedesktop.org>,
<jhubbard@nvidia.com>, <rcampbell@nvidia.com>,
<jglisse@redhat.com>, <hch@infradead.org>, <daniel@ffwll.ch>,
<willy@infradead.org>, "Christoph Hellwig" <hch@lst.de>
Subject: Re: [PATCH v7 5/8] mm: Device exclusive memory access
Date: Thu, 1 Apr 2021 00:27:52 +1100 [thread overview]
Message-ID: <2124945.3NMGunUBXV@nvdebian> (raw)
In-Reply-To: <20210331131854.GI1463678@nvidia.com>
On Thursday, 1 April 2021 12:18:54 AM AEDT Jason Gunthorpe wrote:
> On Wed, Mar 31, 2021 at 11:59:28PM +1100, Alistair Popple wrote:
>
> > I guess that makes sense as the split could go either way at the
> > moment but I should add a check to make sure this isn't used with
> > pinned pages anyway.
>
> Is it possible to have a pinned page under one of these things? If I
> pin it before you migrate it then it remains pinned but hidden under
> the swap entry?
At the moment yes. But I had planned (and this reminded me) to add a check to
prevent marking pinned pages for exclusive access. This check was in the
original migration based implementation as I don't think it makes much sense
to allow exclusive access to pinned pages given it indicates another device is
possibly using it.
> So the special logic is needed and the pinned page has to be copied
> and written as a normal pte, not dropped as a migration entry
Yep, if we end up allowing pinned pages to exist under these then that makes
sense. Thanks for the clarification.
- Alistair
> Jason
>
next prev parent reply other threads:[~2021-03-31 13:45 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 0:07 [PATCH v7 0/8] Add support for SVM atomics in Nouveau Alistair Popple
2021-03-26 0:07 ` [PATCH v7 1/8] mm: Remove special swap entry functions Alistair Popple
2021-03-30 18:38 ` Jason Gunthorpe
2021-03-26 0:07 ` [PATCH v7 2/8] mm/swapops: Rework swap entry manipulation code Alistair Popple
2021-03-26 0:08 ` [PATCH v7 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Alistair Popple
2021-03-30 18:49 ` Jason Gunthorpe
2021-03-30 22:09 ` Alistair Popple
2021-03-30 22:16 ` Alistair Popple
2021-03-30 22:24 ` Jason Gunthorpe
2021-03-30 22:43 ` John Hubbard
2021-03-30 22:56 ` Alistair Popple
2021-03-31 3:56 ` John Hubbard
2021-03-31 4:09 ` John Hubbard
2021-03-31 4:15 ` Alistair Popple
2021-03-31 11:57 ` Jason Gunthorpe
2021-04-01 4:36 ` Alistair Popple
2021-04-01 19:21 ` Shakeel Butt
2021-03-26 0:08 ` [PATCH v7 4/8] mm/rmap: Split migration into its own function Alistair Popple
2021-03-26 0:08 ` [PATCH v7 5/8] mm: Device exclusive memory access Alistair Popple
2021-03-30 19:32 ` Jason Gunthorpe
2021-03-31 12:59 ` Alistair Popple
2021-03-31 13:18 ` Jason Gunthorpe
2021-03-31 13:27 ` Alistair Popple [this message]
2021-03-31 13:46 ` Jason Gunthorpe
2021-04-01 0:45 ` Alistair Popple
2021-04-01 0:48 ` Jason Gunthorpe
2021-04-01 2:20 ` Alistair Popple
2021-04-01 11:55 ` Jason Gunthorpe
2021-03-26 0:08 ` [PATCH v7 6/8] mm: Selftests for exclusive device memory Alistair Popple
2021-03-26 0:08 ` [PATCH v7 7/8] nouveau/svm: Refactor nouveau_range_fault Alistair Popple
2021-03-26 0:08 ` [PATCH v7 8/8] nouveau/svm: Implement atomic SVM access Alistair Popple
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