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Date:   Fri, 6 Dec 2019 08:47:56 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Yang Shi <yang.shi@linux.alibaba.com>
Cc:     mtk.manpages@gmail.com, cl@linux.com, jhubbard@nvidia.com,
        cai@lca.pw, akpm@linux-foundation.org, linux-man@vger.kernel.org,
        linux-api@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] move_pages.2: not return ENOENT if the page are already
 on the target nodes
Message-ID: <20191206074756.GI28317@dhcp22.suse.cz>
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On Fri 06-12-19 09:34:50, Yang Shi wrote:
> Since commit e78bbfa82624 ("mm: stop returning -ENOENT
> from sys_move_pages() if nothing got migrated"), move_pages doesn't
> return -ENOENT anymore if the pages are already on the target nodes, but
> this change is never reflected in manpage.
> 
> Cc: Michael Kerrisk <mtk.manpages@gmail.com>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Qian Cai <cai@lca.pw>
> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
> ---
>  man2/move_pages.2 | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/man2/move_pages.2 b/man2/move_pages.2
> index 2d96468..2a2f3cd 100644
> --- a/man2/move_pages.2
> +++ b/man2/move_pages.2
> @@ -192,9 +192,8 @@ was specified or an attempt was made to migrate pages of a kernel thread.
>  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
> +No pages were found.
> +All pages are either not present, had an invalid address or could not be
>  moved because they were mapped by multiple processes.

I would rather not put any specifics here because those reasons might
differ in future. I would simply go with "No pages were found that
require or could be moved."

-- 
Michal Hocko
SUSE Labs