linux-kernel - Re: [PATCH] ioctl_userfaultfd.2: Corrections for returned .ioctls members

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Date:   Tue, 22 Mar 2022 16:46:35 +0000
From:   Ian Abbott <abbotti@....co.uk>
To:     Axel Rasmussen <axelrasmussen@...gle.com>,
        "Alejandro Colomar (man-pages)" <alx.manpages@...il.com>
Cc:     Peter Xu <peterx@...hat.com>, linux-man@...r.kernel.org,
        Michael Kerrisk <mtk.manpages@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ioctl_userfaultfd.2: Corrections for returned .ioctls
 members

On 22/03/2022 16:36, Axel Rasmussen wrote:
> On Tue, Mar 22, 2022 at 9:23 AM Axel Rasmussen <axelrasmussen@...gle.com> wrote:
>>
>> On Tue, Mar 22, 2022 at 5:32 AM Alejandro Colomar (man-pages)
>> <alx.manpages@...il.com> wrote:
>>>
>>> Hi Ian and Peter,
>>>
>>> On 3/21/22 07:10, Peter Xu wrote:
>>>> On Fri, Mar 18, 2022 at 07:13:43PM +0000, Ian Abbott wrote:
>>>>> Support for the `UFFDIO_WRITEPROTECT` operation is not indicated in the
>>>>> `ioctls` member of `struct uffdio_api`.  It is indicated in the `ioctls`
>>>>> member of `struct uffdio_register` along with indications of support for
>>>>> the `UFFDIO_COPY`, `UFFDIO_WAKE` and `UFFDIO_ZEROPAGE` operations (and
>>>>> also the `UFFDIO_CONTINUE` operation supported since Linux 5.13 but
>>>>> that is not documented by this man page yet.)
>>>>
>>>> I thought it should have landed but indeed it's not.  Copying Axel.
>>
>> Ah, I mistakenly thought it got merged, but there were a few remaining
>> issues Alejandro wanted addressed first. I'll send a v3 of it later
>> today.
>>
>> For what it's worth, as part of adding minor fault handling, we pretty
>> significantly change the ioctl field's behavior, and I rewrote a lot
>> of the documentation around it. So, it may conflict with this patch.
>> :/ Sorry about that.
> 
> Heh, I spoke too soon. My patch doesn't touch this after all, I think
> the patches don't conflict. :) It's been a while since I looked at
> it...

I guess the section (in my patch) that indicates supported ioctls in 
`struct uffdio_register` would still need tweaking to mention 
`UFFDIO_CONTINUE` though, so either one of the patches will need to 
change or another little patch will be needed.

-- 
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