Re: [PATCH] mm/debug: sync up latest migrate_reason to migrate_reason_names

[John Hubbard]

On 9/17/21 00:03, Huang, Ying wrote:
> Weizhao Ouyang <o451686892@xxxxxxxxx> writes:
>
> > After related migrate page updates, sync up latest migrate_reason to
> > migrate_reason_names, page_owner use it to parse the page migrate
> > reason.
> >
> > Fixes: d1e153fea2a8 ("mm/gup: migrate pinned pages out of movable zone")
> > Fixes: 26aa2d199d6f ("mm/migrate: demote pages during reclaim")
> > Signed-off-by: Weizhao Ouyang <o451686892@xxxxxxxxx>
> > ---
> >   mm/debug.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/mm/debug.c b/mm/debug.c
> > index e73fe0a8ec3d..733770b0ed0c 100644
> > --- a/mm/debug.c
> > +++ b/mm/debug.c
> > @@ -25,6 +25,8 @@ const char *migrate_reason_names[MR_TYPES] = {
> >   	"mempolicy_mbind",
> >   	"numa_misplaced",
> >   	"cma",
> > +	"longterm_pin",
> > +	"demotion",
> >   };
> >   
> >   const struct trace_print_flags pageflag_names[] = {
>
> Good catch!  Thanks!
>
> Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
>
> It may be better to use BUILD_BUG_ON() to capture similar issue earlier?

Yes! Or if BUILD_BUG_ON() can't work here, then at least a comment in the
various locations, explaining that these must be kept in sync. But
BUILD_BUG_ON() should work, I think.


thanks,
--
John Hubbard
NVIDIA