Re: [PATCH] move_pages.2: not return ENOENT if the page are already on the target nodes

[John Hubbard]

On 12/5/19 5:34 PM, 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@xxxxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxx>
> Cc: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Qian Cai <cai@xxxxxx>
> Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> ---
>   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.
>   .TP
>   .B EPERM

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?

If so, we need to redo this part of the man page.


thanks,
--
John Hubbard
NVIDIA