On Mon 23-05-16 16:32:56, Hugh Dickins wrote:
> On Mon, 23 May 2016, Andrew Morton wrote:
> > On Fri, 20 May 2016 15:31:21 +0200 Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> > > On Fri 20-05-16 15:19:12, Vlastimil Babka wrote:
> > > > On 05/20/2016 03:06 PM, Michal Hocko wrote:
> > > [...]
> > > > > Why don't we need also to count also retries?
> > > >
> > > > We could, but not like you suggest.
> > > >
> > > > > ---
> > > > > diff --git a/mm/migrate.c b/mm/migrate.c
> > > > > index 53ab6398e7a2..ef9c5211ae3c 100644
> > > > > --- a/mm/migrate.c
> > > > > +++ b/mm/migrate.c
> > > > > @@ -1190,9 +1190,9 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
> > > > > }
> > > > > }
> > > > > }
> > > > > +out:
> > > > > nr_failed += retry;
> > > > > rc = nr_failed;
> > > >
> > > > This overwrites rc == -ENOMEM, which at least compaction needs to recognize.
> > > > But we could duplicate "nr_failed += retry" in the case -ENOMEM.
> > >
> > > Right you are. So we should do
> > > ---
> > > diff --git a/mm/migrate.c b/mm/migrate.c
> > > index 53ab6398e7a2..123fed94022b 100644
> > > --- a/mm/migrate.c
> > > +++ b/mm/migrate.c
> > > @@ -1171,6 +1171,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
> > >
> > > switch(rc) {
> > > case -ENOMEM:
> > > + nr_failed += retry + 1;
> > > goto out;
> > > case -EAGAIN:
> > > retry++;
> > >
> > >
> >
> > argh, this was lost. Please resend as a real patch sometime?
>
> It's not correct. "retry" is reset to 0 each time around the
> loop, and it's only a meaningful number to add on to nr_failed, in
> the case when we've gone through the whole list: not in this "goto
> out" case.
You are right! I've missed that, my bad.
> We could add another loop to count how many are left
> when we hit -ENOMEM, and add that on to nr_failed; but I'm not
> convinced that it's worth the bother.
Agreed!
Sorry about the noise!
--
Michal Hocko
SUSE Labs
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