On Wed 20-03-19 12:12:09, Andrew Morton wrote:
> On Wed, 20 Mar 2019 16:07:32 +0800 Baoquan He <bhe@xxxxxxxxxx> wrote:
>
> > In function node_states_check_changes_online(), N_HIGH_MEMORY is used
> > to substitute ZONE_HIGHMEM directly. This is not right. N_HIGH_MEMORY
> > always has value '3' if CONFIG_HIGHMEM=y, while ZONE_HIGHMEM's value
> > is not. It depends on whether CONFIG_ZONE_DMA/CONFIG_ZONE_DMA32 are
> > enabled. Obviously it's not true for CONFIG_ZONE_DMA32 on 32bit system,
> > and CONFIG_ZONE_DMA is also optional.
> >
> > Replace it with ZONE_HIGHMEM.
> >
> > Fixes: 8efe33f40f3e ("mm/memory_hotplug.c: simplify node_states_check_changes_online")
>
> What are the runtime effects of this change?
There shouldn't be none. The code is just messy. The newer changelog
should make it more clear I believe.
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -712,7 +712,7 @@ static void node_states_check_changes_online(unsigned long nr_pages,
> > if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY))
> > arg->status_change_nid_normal = nid;
> > #ifdef CONFIG_HIGHMEM
> > - if (zone_idx(zone) <= N_HIGH_MEMORY && !node_state(nid, N_HIGH_MEMORY))
> > + if (zone_idx(zone) <= ZONE_HIGHMEM && !node_state(nid, N_HIGH_MEMORY))
> > arg->status_change_nid_high = nid;
> > #endif
> > }
>
--
Michal Hocko
SUSE Labs
