From: Jason Gunthorpe <jgg@nvidia.com>
To: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>,
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,
dri-devel@lists.freedesktop.org, jhubbard@nvidia.com,
rcampbell@nvidia.com, jglisse@redhat.com, hch@infradead.org,
daniel@ffwll.ch, willy@infradead.org, bsingharora@gmail.com,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v8 5/8] mm: Device exclusive memory access
Date: Tue, 18 May 2021 16:45:09 -0300 [thread overview]
Message-ID: <20210518194509.GF1002214@nvidia.com> (raw)
In-Reply-To: <YKQBACJCjsxeM3ro@t490s>
On Tue, May 18, 2021 at 02:01:36PM -0400, Peter Xu wrote:
> > > Indeed it'll be odd for a COW page since for COW page then it means after
> > > parent/child writting to the page it'll clone into two, then it's a mistery on
> > > which one will be the one that "exclusived owned" by the device..
> >
> > For COW pages it is like every other fork case.. We can't reliably
> > write-protect the device_exclusive page during fork so we must copy it
> > at fork time.
> >
> > Thus three reasonable choices:
> > - Copy to a new CPU page
> > - Migrate back to a CPU page and write protect it
> > - Copy to a new device exclusive page
>
> IMHO the ownership question would really help us to answer this one..
I'm confused about what device ownership you are talking about
It is just a page and it is tied to some specific pgmap?
If the thing providing the migration stuff goes away then all
device_exclusive pages should revert back to CPU pages and destroy the
pgmap?
Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Peter Xu <peterx@redhat.com>
Cc: rcampbell@nvidia.com, willy@infradead.org,
linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org,
bsingharora@gmail.com, Alistair Popple <apopple@nvidia.com>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
hch@infradead.org, linux-mm@kvack.org, bskeggs@redhat.com,
daniel@ffwll.ch, akpm@linux-foundation.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [Nouveau] [PATCH v8 5/8] mm: Device exclusive memory access
Date: Tue, 18 May 2021 16:45:09 -0300 [thread overview]
Message-ID: <20210518194509.GF1002214@nvidia.com> (raw)
In-Reply-To: <YKQBACJCjsxeM3ro@t490s>
On Tue, May 18, 2021 at 02:01:36PM -0400, Peter Xu wrote:
> > > Indeed it'll be odd for a COW page since for COW page then it means after
> > > parent/child writting to the page it'll clone into two, then it's a mistery on
> > > which one will be the one that "exclusived owned" by the device..
> >
> > For COW pages it is like every other fork case.. We can't reliably
> > write-protect the device_exclusive page during fork so we must copy it
> > at fork time.
> >
> > Thus three reasonable choices:
> > - Copy to a new CPU page
> > - Migrate back to a CPU page and write protect it
> > - Copy to a new device exclusive page
>
> IMHO the ownership question would really help us to answer this one..
I'm confused about what device ownership you are talking about
It is just a page and it is tied to some specific pgmap?
If the thing providing the migration stuff goes away then all
device_exclusive pages should revert back to CPU pages and destroy the
pgmap?
Jason
_______________________________________________
Nouveau mailing list
Nouveau@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/nouveau
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Peter Xu <peterx@redhat.com>
Cc: rcampbell@nvidia.com, willy@infradead.org,
linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org,
bsingharora@gmail.com, Alistair Popple <apopple@nvidia.com>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
hch@infradead.org, linux-mm@kvack.org, jglisse@redhat.com,
bskeggs@redhat.com, jhubbard@nvidia.com,
akpm@linux-foundation.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v8 5/8] mm: Device exclusive memory access
Date: Tue, 18 May 2021 16:45:09 -0300 [thread overview]
Message-ID: <20210518194509.GF1002214@nvidia.com> (raw)
In-Reply-To: <YKQBACJCjsxeM3ro@t490s>
On Tue, May 18, 2021 at 02:01:36PM -0400, Peter Xu wrote:
> > > Indeed it'll be odd for a COW page since for COW page then it means after
> > > parent/child writting to the page it'll clone into two, then it's a mistery on
> > > which one will be the one that "exclusived owned" by the device..
> >
> > For COW pages it is like every other fork case.. We can't reliably
> > write-protect the device_exclusive page during fork so we must copy it
> > at fork time.
> >
> > Thus three reasonable choices:
> > - Copy to a new CPU page
> > - Migrate back to a CPU page and write protect it
> > - Copy to a new device exclusive page
>
> IMHO the ownership question would really help us to answer this one..
I'm confused about what device ownership you are talking about
It is just a page and it is tied to some specific pgmap?
If the thing providing the migration stuff goes away then all
device_exclusive pages should revert back to CPU pages and destroy the
pgmap?
Jason
next prev parent reply other threads:[~2021-05-18 19:45 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 8:42 [PATCH v8 0/8] Add support for SVM atomics in Nouveau Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-04-07 8:42 ` [PATCH v8 1/8] mm: Remove special swap entry functions Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-05-18 2:17 ` Peter Xu
2021-05-18 2:17 ` Peter Xu
2021-05-18 2:17 ` [Nouveau] " Peter Xu
2021-05-18 11:58 ` Alistair Popple
2021-05-18 11:58 ` Alistair Popple
2021-05-18 11:58 ` [Nouveau] " Alistair Popple
2021-05-18 14:17 ` Peter Xu
2021-05-18 14:17 ` Peter Xu
2021-05-18 14:17 ` [Nouveau] " Peter Xu
2021-04-07 8:42 ` [PATCH v8 2/8] mm/swapops: Rework swap entry manipulation code Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-04-07 8:42 ` [PATCH v8 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-05-18 20:04 ` Liam Howlett
2021-05-18 20:04 ` Liam Howlett
2021-05-18 20:04 ` [Nouveau] " Liam Howlett
2021-05-19 12:38 ` Alistair Popple
2021-05-19 12:38 ` Alistair Popple
2021-05-19 12:38 ` [Nouveau] " Alistair Popple
2021-05-20 20:24 ` Liam Howlett
2021-05-20 20:24 ` Liam Howlett
2021-05-20 20:24 ` [Nouveau] " Liam Howlett
2021-05-21 2:23 ` Alistair Popple
2021-05-21 2:23 ` Alistair Popple
2021-05-21 2:23 ` [Nouveau] " Alistair Popple
2021-04-07 8:42 ` [PATCH v8 4/8] mm/rmap: Split migration into its own function Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-04-07 8:42 ` [PATCH v8 5/8] mm: Device exclusive memory access Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-05-18 2:08 ` Peter Xu
2021-05-18 2:08 ` Peter Xu
2021-05-18 2:08 ` [Nouveau] " Peter Xu
2021-05-18 13:19 ` Alistair Popple
2021-05-18 13:19 ` Alistair Popple
2021-05-18 13:19 ` [Nouveau] " Alistair Popple
2021-05-18 17:27 ` Peter Xu
2021-05-18 17:27 ` Peter Xu
2021-05-18 17:27 ` [Nouveau] " Peter Xu
2021-05-18 17:33 ` Jason Gunthorpe
2021-05-18 17:33 ` Jason Gunthorpe
2021-05-18 17:33 ` [Nouveau] " Jason Gunthorpe
2021-05-18 18:01 ` Peter Xu
2021-05-18 18:01 ` Peter Xu
2021-05-18 18:01 ` [Nouveau] " Peter Xu
2021-05-18 19:45 ` Jason Gunthorpe [this message]
2021-05-18 19:45 ` Jason Gunthorpe
2021-05-18 19:45 ` [Nouveau] " Jason Gunthorpe
2021-05-18 20:29 ` Peter Xu
2021-05-18 20:29 ` Peter Xu
2021-05-18 20:29 ` [Nouveau] " Peter Xu
2021-05-18 23:03 ` Jason Gunthorpe
2021-05-18 23:03 ` Jason Gunthorpe
2021-05-18 23:03 ` [Nouveau] " Jason Gunthorpe
2021-05-18 23:45 ` Peter Xu
2021-05-18 23:45 ` Peter Xu
2021-05-18 23:45 ` [Nouveau] " Peter Xu
2021-05-19 11:04 ` Alistair Popple
2021-05-19 11:04 ` Alistair Popple
2021-05-19 11:04 ` [Nouveau] " Alistair Popple
2021-05-19 12:15 ` Peter Xu
2021-05-19 12:15 ` Peter Xu
2021-05-19 12:15 ` [Nouveau] " Peter Xu
2021-05-19 13:11 ` Alistair Popple
2021-05-19 13:11 ` Alistair Popple
2021-05-19 13:11 ` [Nouveau] " Alistair Popple
2021-05-19 14:04 ` Peter Xu
2021-05-19 14:04 ` Peter Xu
2021-05-19 14:04 ` [Nouveau] " Peter Xu
2021-05-19 13:28 ` Jason Gunthorpe
2021-05-19 13:28 ` Jason Gunthorpe
2021-05-19 13:28 ` [Nouveau] " Jason Gunthorpe
2021-05-19 14:09 ` Peter Xu
2021-05-19 14:09 ` Peter Xu
2021-05-19 14:09 ` [Nouveau] " Peter Xu
2021-05-19 18:11 ` Jason Gunthorpe
2021-05-19 18:11 ` Jason Gunthorpe
2021-05-19 18:11 ` [Nouveau] " Jason Gunthorpe
2021-05-19 11:35 ` Alistair Popple
2021-05-19 11:35 ` Alistair Popple
2021-05-19 11:35 ` [Nouveau] " Alistair Popple
2021-05-19 12:21 ` Peter Xu
2021-05-19 12:21 ` Peter Xu
2021-05-19 12:21 ` [Nouveau] " Peter Xu
2021-05-19 12:46 ` Alistair Popple
2021-05-19 12:46 ` Alistair Popple
2021-05-19 12:46 ` [Nouveau] " Alistair Popple
2021-05-21 6:53 ` Alistair Popple
2021-05-21 6:53 ` Alistair Popple
2021-05-21 6:53 ` [Nouveau] " Alistair Popple
2021-05-18 21:16 ` Peter Xu
2021-05-18 21:16 ` Peter Xu
2021-05-18 21:16 ` [Nouveau] " Peter Xu
2021-05-19 10:49 ` Alistair Popple
2021-05-19 10:49 ` Alistair Popple
2021-05-19 10:49 ` [Nouveau] " Alistair Popple
2021-05-19 12:24 ` Peter Xu
2021-05-19 12:24 ` Peter Xu
2021-05-19 12:24 ` [Nouveau] " Peter Xu
2021-05-19 12:46 ` Alistair Popple
2021-05-19 12:46 ` Alistair Popple
2021-05-19 12:46 ` [Nouveau] " Alistair Popple
2021-04-07 8:42 ` [PATCH v8 6/8] mm: Selftests for exclusive device memory Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-04-07 8:42 ` [PATCH v8 7/8] nouveau/svm: Refactor nouveau_range_fault Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-04-07 8:42 ` [PATCH v8 8/8] nouveau/svm: Implement atomic SVM access Alistair Popple
2021-04-07 8:42 ` Alistair Popple
2021-04-07 8:42 ` [Nouveau] " Alistair Popple
2021-05-21 4:04 ` Ben Skeggs
2021-05-21 4:04 ` Ben Skeggs
2021-05-21 4:04 ` [Nouveau] " Ben Skeggs
2021-05-21 4:04 ` Ben Skeggs
2021-05-06 7:43 ` [PATCH v8 0/8] Add support for SVM atomics in Nouveau Alistair Popple
2021-05-06 7:43 ` Alistair Popple
2021-05-06 7:43 ` [Nouveau] " Alistair Popple
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