From: Peter Xu <peterx@redhat.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: Jason Gunthorpe <jgg@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: Wed, 19 May 2021 08:15:41 -0400 [thread overview]
Message-ID: <YKUBbVuvm5FUJRMl@t490s> (raw)
In-Reply-To: <2235357.HsqDk0zIjc@nvdebian>
On Wed, May 19, 2021 at 09:04:53PM +1000, Alistair Popple wrote:
> Failing fork() because we couldn't take a lock doesn't seem like the right
> approach though, especially as there is already existing code that retries. I
> get this adds complexity though, so would be happy to take a look at cleaning
> copy_pte_range() up in future.
Yes, I proposed that as this one won't affect any existing applications (unlike
the existing ones) but only new userspace driver apps that will use this new
atomic feature.
IMHO it'll be a pity to add extra complexity and maintainance burden into
fork() if only for keeping the "logical correctness of fork()" however the code
never triggers. If we start with trylock we'll know whether people will use it,
since people will complain with a reason when needed; however I still doubt
whether a sane userspace device driver should fork() within busy interaction
with the device underneath..
In all cases, please still consider to keep them in copy_nonpresent_pte() (and
if to rework, separating patches would be great).
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-05-19 12:15 UTC|newest]
Thread overview: 42+ 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 ` [PATCH v8 1/8] mm: Remove special swap entry functions Alistair Popple
2021-05-18 2:17 ` Peter Xu
2021-05-18 11:58 ` Alistair Popple
2021-05-18 14:17 ` 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 ` [PATCH v8 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Alistair Popple
2021-05-18 20:04 ` Liam Howlett
2021-05-19 12:38 ` Alistair Popple
2021-05-20 20:24 ` Liam Howlett
2021-05-21 2:23 ` 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 ` [PATCH v8 5/8] mm: Device exclusive memory access Alistair Popple
2021-05-18 2:08 ` Peter Xu
2021-05-18 13:19 ` Alistair Popple
2021-05-18 17:27 ` Peter Xu
2021-05-18 17:33 ` Jason Gunthorpe
2021-05-18 18:01 ` Peter Xu
2021-05-18 19:45 ` Jason Gunthorpe
2021-05-18 20:29 ` Peter Xu
2021-05-18 23:03 ` Jason Gunthorpe
2021-05-18 23:45 ` Peter Xu
2021-05-19 11:04 ` Alistair Popple
2021-05-19 12:15 ` Peter Xu [this message]
2021-05-19 13:11 ` Alistair Popple
2021-05-19 14:04 ` Peter Xu
2021-05-19 13:28 ` Jason Gunthorpe
2021-05-19 14:09 ` Peter Xu
2021-05-19 18:11 ` Jason Gunthorpe
2021-05-19 11:35 ` Alistair Popple
2021-05-19 12:21 ` Peter Xu
2021-05-19 12:46 ` Alistair Popple
2021-05-21 6:53 ` Alistair Popple
2021-05-18 21:16 ` Peter Xu
2021-05-19 10:49 ` Alistair Popple
2021-05-19 12:24 ` Peter Xu
2021-05-19 12:46 ` Alistair Popple
2021-04-07 8:42 ` [PATCH v8 6/8] mm: Selftests for exclusive device memory Alistair Popple
2021-04-07 8:42 ` [PATCH v8 7/8] nouveau/svm: Refactor nouveau_range_fault Alistair Popple
2021-04-07 8:42 ` [PATCH v8 8/8] nouveau/svm: Implement atomic SVM access Alistair Popple
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
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