Re: [patch] mm, migrate: increment fail count on ENOMEM

From: Andrew Morton
Date: Mon May 23 2016 - 18:02:10 EST


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?

Thanks.