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From: Jens Axboe <[email protected]>
To: David Hildenbrand <[email protected]>,
	Lorenzo Stoakes <[email protected]>,
	[email protected], [email protected],
	Andrew Morton <[email protected]>
Cc: Matthew Wilcox <[email protected]>,
	Pavel Begunkov <[email protected]>,
	[email protected], Jason Gunthorpe <[email protected]>,
	John Hubbard <[email protected]>
Subject: Re: [PATCH v5 4/6] io_uring: rsrc: delegate VMA file-backed check to GUP
Date: Tue, 16 May 2023 07:19:52 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 5/16/23 2:25?AM, David Hildenbrand wrote:
> On 15.05.23 21:55, Jens Axboe wrote:
>> On 5/14/23 3:26?PM, Lorenzo Stoakes wrote:
>>> Now that the GUP explicitly checks FOLL_LONGTERM pin_user_pages() for
>>> broken file-backed mappings in "mm/gup: disallow FOLL_LONGTERM GUP-nonfast
>>> writing to file-backed mappings", there is no need to explicitly check VMAs
>>> for this condition, so simply remove this logic from io_uring altogether.
>>
>> Don't have the prerequisite patch handy (not in mainline yet), but if it
>> just moves the check, then:
>>
>> Reviewed-by: Jens Axboe <[email protected]>
>>
> 
> Jens, please see my note regarding iouring:
> 
> https://lore.kernel.org/bpf/[email protected]/
> 
> With this patch, MAP_PRIVATE will work as expected (2), but there will
> be a change in return code handling (1) that we might have to document
> in the man page.

I think documenting that newer kernels will return -EFAULT rather than
-EOPNOTSUPP should be fine. It's not a new failure case, just a
different error value for an already failing case. Should be fine with
just a doc update. Will do that now.

-- 
Jens Axboe


  reply	other threads:[~2023-05-16 13:20 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <[email protected]>
2023-05-14 21:26 ` [PATCH v5 4/6] io_uring: rsrc: delegate VMA file-backed check to GUP Lorenzo Stoakes
2023-05-15 11:50   ` Christoph Hellwig
2023-05-15 19:55   ` Jens Axboe
2023-05-16  8:25     ` David Hildenbrand
2023-05-16 13:19       ` Jens Axboe [this message]
2023-05-16  8:28   ` David Hildenbrand
2023-05-14 21:26 ` [PATCH v5 5/6] mm/gup: remove vmas parameter from pin_user_pages() Lorenzo Stoakes
2023-05-15 11:50   ` Christoph Hellwig
2023-05-17 13:04   ` Sakari Ailus

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