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

[Yang Shi]

On 12/6/19 12:25 AM, John Hubbard wrote:
> 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>
> > ---
> > Â man2/move_pages.2 | 5 ++---
> > Â 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.
> > Â One of the target nodes is not online.
> > Â .TP
> > Â .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
> > Â moved because they were mapped by multiple processes.
> > Â .TP
> > Â .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?

Nice catch. Yes, you are right.

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

Yes.

> thanks,