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From: Jens Axboe <[email protected]>
To: Jason Gunthorpe <[email protected]>, Matthew Wilcox <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>,
	[email protected], [email protected],
	Andrew Morton <[email protected]>,
	David Hildenbrand <[email protected]>,
	Pavel Begunkov <[email protected]>,
	[email protected]
Subject: Re: [PATCH v4 4/6] io_uring: rsrc: avoid use of vmas parameter in pin_user_pages()
Date: Wed, 19 Apr 2023 14:18:31 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 4/19/23 2:15 PM, Jens Axboe wrote:
> On 4/19/23 12:24?PM, Jason Gunthorpe wrote:
>> On Wed, Apr 19, 2023 at 07:23:00PM +0100, Matthew Wilcox wrote:
>>> On Wed, Apr 19, 2023 at 07:18:26PM +0100, Lorenzo Stoakes wrote:
>>>> So even if I did the FOLL_ALLOW_BROKEN_FILE_MAPPING patch series first, I
>>>> would still need to come along and delete a bunch of your code
>>>> afterwards. And unfortunately Pavel's recent change which insists on not
>>>> having different vm_file's across VMAs for the buffer would have to be
>>>> reverted so I expect it might not be entirely without discussion.
>>>
>>> I don't even understand why Pavel wanted to make this change.  The
>>> commit log really doesn't say.
>>>
>>> commit edd478269640
>>> Author: Pavel Begunkov <[email protected]>
>>> Date:   Wed Feb 22 14:36:48 2023 +0000
>>>
>>>     io_uring/rsrc: disallow multi-source reg buffers
>>>
>>>     If two or more mappings go back to back to each other they can be passed
>>>     into io_uring to be registered as a single registered buffer. That would
>>>     even work if mappings came from different sources, e.g. it's possible to
>>>     mix in this way anon pages and pages from shmem or hugetlb. That is not
>>>     a problem but it'd rather be less prone if we forbid such mixing.
>>>
>>>     Cc: <[email protected]>
>>>     Signed-off-by: Pavel Begunkov <[email protected]>
>>>     Signed-off-by: Jens Axboe <[email protected]>
>>>
>>> It even says "That is not a problem"!  So why was this patch merged
>>> if it's not fixing a problem?
>>>
>>> It's now standing in the way of an actual cleanup.  So why don't we
>>> revert it?  There must be more to it than this ...
>>
>> https://lore.kernel.org/all/[email protected]/
> 
> Let's just kill that patch that, I can add a revert for 6.4. I had
> forgotten about that patch and guess I didn't realize that most of the
> issue do in fact just stem from that.

https://git.kernel.dk/cgit/linux-block/commit/?h=for-6.4/io_uring&id=fbd3aaf37886d3645b1bd6920f6298f5884049f8

-- 
Jens Axboe



  reply	other threads:[~2023-04-19 20:18 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <[email protected]>
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
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 [this message]
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

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