From: Jason Gunthorpe <jgg@nvidia.com>
To: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Jens Axboe <axboe@kernel.dk>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@redhat.com>,
Pavel Begunkov <asml.silence@gmail.com>,
io-uring@vger.kernel.org
Subject: Re: [PATCH v4 4/6] io_uring: rsrc: avoid use of vmas parameter in pin_user_pages()
Date: Wed, 19 Apr 2023 20:22:51 -0300 [thread overview]
Message-ID: <ZEB3y0V2GSDcUMc2@nvidia.com> (raw)
In-Reply-To: <8bf0df41-27ef-4305-b424-e43045a6d68d@lucifer.local>
On Wed, Apr 19, 2023 at 07:45:06PM +0100, Lorenzo Stoakes wrote:
> For example, imagine if a user (yes it'd be weird) mlock'd some pages in a
> buffer and not others, then we'd break their use case. Also (perhaps?) more
> feasibly, a user might mix hugetlb and anon pages. So I think that'd be too
> restrictive here.
Yeah, I agree we should not add a broad single-vma restriction to
GUP. It turns any split of a VMA into a potentially uABI breaking
change and we just don't need that headache in the mm..
> I do like the idea of a FOLL_SINGLE_VMA for other use cases though, the
> majority of which want one and one page only. Perhaps worth taking the
> helper added in this series (get_user_page_vma_remote() from [1]) and
> replacing it with an a full GUP function which has an interface explicitly
> for this common single page/vma case.
Like I showed in another thread a function signature that can only do
one page and also returns the VMA would force it to be used properly
and we don't need a FOLL flag.
Jason
next prev parent reply other threads:[~2023-04-19 23:22 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-18 15:48 [PATCH v4 0/6] remove the vmas parameter from GUP APIs Lorenzo Stoakes
2023-04-18 15:49 ` [PATCH v4 1/6] mm/gup: remove unused vmas parameter from get_user_pages() Lorenzo Stoakes
2023-04-19 8:40 ` Christian König
2023-04-23 15:12 ` Jarkko Sakkinen
2023-04-18 15:49 ` [PATCH v4 2/6] mm/gup: remove unused vmas parameter from pin_user_pages_remote() Lorenzo Stoakes
2023-04-18 15:49 ` [PATCH v4 3/6] mm/gup: remove vmas parameter from get_user_pages_remote() Lorenzo Stoakes
2023-04-19 12:05 ` Janosch Frank
2023-04-18 15:49 ` [PATCH v4 4/6] io_uring: rsrc: avoid use of vmas parameter in pin_user_pages() Lorenzo Stoakes
2023-04-18 15:55 ` David Hildenbrand
2023-04-18 15:56 ` David Hildenbrand
2023-04-18 16:25 ` Lorenzo Stoakes
2023-04-19 16:35 ` Jens Axboe
2023-04-19 16:59 ` Jens Axboe
2023-04-19 17:23 ` Lorenzo Stoakes
2023-04-19 17:35 ` Jens Axboe
2023-04-19 17:47 ` Lorenzo Stoakes
2023-04-19 17:51 ` Jens Axboe
2023-04-19 18:18 ` Lorenzo Stoakes
2023-04-19 18:22 ` Jason Gunthorpe
2023-04-19 18:50 ` Lorenzo Stoakes
2023-04-19 18:23 ` Matthew Wilcox
2023-04-19 18:24 ` Jason Gunthorpe
2023-04-19 18:35 ` Matthew Wilcox
2023-04-19 18:45 ` Lorenzo Stoakes
2023-04-19 23:22 ` Jason Gunthorpe [this message]
2023-04-20 13:57 ` Lorenzo Stoakes
2023-04-20 13:36 ` Pavel Begunkov
2023-04-20 14:19 ` Lorenzo Stoakes
2023-04-20 15:31 ` Jason Gunthorpe
2023-04-19 20:15 ` Jens Axboe
2023-04-19 20:18 ` Jens Axboe
2023-04-20 13:37 ` Pavel Begunkov
2023-04-19 17:07 ` Lorenzo Stoakes
2023-04-18 15:49 ` [PATCH v4 5/6] mm/gup: remove vmas parameter from pin_user_pages() Lorenzo Stoakes
2023-04-18 15:49 ` [PATCH v4 6/6] mm/gup: remove vmas array from internal GUP functions Lorenzo Stoakes
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