Re: [PATCH v3 03/11] s390x/mm: Implement arch_remove_memory()

Michal Hocko
2019-07-01T12:47:17Z

On Mon 01-07-19 09:45:03, Michal Hocko wrote:
> On Mon 27-05-19 13:11:44, David Hildenbrand wrote:
> > Will come in handy when wanting to handle errors after
> > arch_add_memory().
>
> I do not understand this. Why do you add a code for something that is
> not possible on this HW (based on the comment - is it still valid btw?)

Same as the previous patch (drop it).

> > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Michal Hocko <mhocko@suse.com>
> > Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
> > Cc: David Hildenbrand <david@redhat.com>
> > Cc: Vasily Gorbik <gor@linux.ibm.com>
> > Cc: Oscar Salvador <osalvador@suse.com>
> > Signed-off-by: David Hildenbrand <david@redhat.com>
> > ---
> > arch/s390/mm/init.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> > index d552e330fbcc..14955e0a9fcf 100644
> > --- a/arch/s390/mm/init.c
> > +++ b/arch/s390/mm/init.c
> > @@ -243,12 +243,13 @@ int arch_add_memory(int nid, u64 start, u64 size,
> > void arch_remove_memory(int nid, u64 start, u64 size,
> > struct vmem_altmap *altmap)
> > {
> > - /*
> > - * There is no hardware or firmware interface which could trigger a
> > - * hot memory remove on s390. So there is nothing that needs to be
> > - * implemented.
> > - */
> > - BUG();
> > + unsigned long start_pfn = start >> PAGE_SHIFT;
> > + unsigned long nr_pages = size >> PAGE_SHIFT;
> > + struct zone *zone;
> > +
> > + zone = page_zone(pfn_to_page(start_pfn));
> > + __remove_pages(zone, start_pfn, nr_pages, altmap);
> > + vmem_remove_mapping(start, size);
> > }
> > #endif
> > #endif /* CONFIG_MEMORY_HOTPLUG */
> > --
> > 2.20.1
> >
>
> --
> Michal Hocko
> SUSE Labs

--
Michal Hocko
SUSE Labs