Re: [PATCH 2/2 - v2] MM: Discard NR_UNSTABLE_NFS, use NR_WRITEBACK instead.

Michal Hocko
2020-04-03T11:04:04Z

On Fri 03-04-20 11:42:20, Jan Kara wrote:
[...]
> > diff --git a/mm/vmstat.c b/mm/vmstat.c
> > index 78d53378db99..d1291537bbb9 100644
> > --- a/mm/vmstat.c
> > +++ b/mm/vmstat.c
> > @@ -1162,7 +1162,6 @@ const char * const vmstat_text[] = {
> > "nr_file_hugepages",
> > "nr_file_pmdmapped",
> > "nr_anon_transparent_hugepages",
> > - "nr_unstable",
> > "nr_vmscan_write",
> > "nr_vmscan_immediate_reclaim",
> > "nr_dirtied",
>
> This is probably the most tricky to deal with given how /proc/vmstat is
> formatted. OTOH for this file there's good chance we'd get away with just
> deleting nr_unstable line because there are entries added to it in the
> middle (e.g. in 60fbf0ab5da1 last September) and nobody complained yet.
>
> What do mm people think? How were changes to vmstat counters handled in the
> past?

Adding new counters in the middle seems to be generally OK. I would be
more worried about removing counters though. So if we can simply print a
phone value at the very end then this should be a reasonable workaround.
--
Michal Hocko
SUSE Labs