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Subject: Re: [PATCH] move_pages.2: not return ENOENT if the page are already
 on the target nodes
To:     John Hubbard <jhubbard@nvidia.com>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>,
        cl@linux.com, mhocko@suse.com, cai@lca.pw,
        akpm@linux-foundation.org
Cc:     linux-man@vger.kernel.org, linux-api@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <1575596090-115377-1-git-send-email-yang.shi@linux.alibaba.com>
 <0dc96e40-5f2b-a2fe-6e5f-b6f3d5e9ebde@nvidia.com>
 <95170ea5-5b62-9168-fcd9-93b43330a1b4@linux.alibaba.com>
 <092adc11-7039-9343-7067-0e0199c9dc13@gmail.com>
 <51dd767a-221f-882d-c7f6-45bd0c217a67@nvidia.com>
From:   Yang Shi <yang.shi@linux.alibaba.com>
Message-ID: <51a37061-8d95-eca1-a1d9-e6e8f4dc884d@linux.alibaba.com>
Date:   Mon, 30 Dec 2019 18:49:29 -0800
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On 12/17/19 11:36 PM, John Hubbard wrote:
> On 12/13/19 5:55 PM, Michael Kerrisk (man-pages) wrote:
> ...
>>>> whoa, hold on. If I'm reading through the various error paths
>>>> correctly, then this
>>>> code is *never* going to return ENOENT for the whole function. It can
>>>> fill in that
>>>> value per-page, in the status array, but that's all. Did I get that
>>>> right?
>>>
>>> Nice catch. Yes, you are right.
>>>
>>>>
>>>> If so, we need to redo this part of the man page.
>>>
>>> Yes.
>>
>> So where are things at with this? Is an improved man-pages
>> patch on the way, or is some other action (on the API) planned?
>>
>
> I was waiting to see if Yang was going to respond...anyway, I think
> we're looking at approximately this sort of change:
>

Hi John,

I apologize for the delay, just came back from vacation. Thanks for 
taking care of the patch.

> diff --git a/man2/move_pages.2 b/man2/move_pages.2
> index 2d96468fa..1bf1053f2 100644
> --- a/man2/move_pages.2
> +++ b/man2/move_pages.2
> @@ -191,12 +191,6 @@ was specified or an attempt was made to migrate 
> pages of a kernel thread.
>  .B ENODEV
>  One of the target nodes is not online.
>  .TP
> -.B ENOENT
> -No pages were found that require moving.
> -All pages are either already
> -on the target node, not present, had an invalid address or could not be
> -moved because they were mapped by multiple processes.
> -.TP
>  .B EPERM
>  The caller specified
>  .B MPOL_MF_MOVE_ALL
>
> ...But I'm not sure if we should change the implementation, instead, so
> that it *can* return ENOENT. That's the main question to resolve before
> creating any more patches, I think.
>
> In addition, Michal mentioned that the page states in the status array 
> also
> need updated documentation.
>
>
> thanks,