Re: [PATCH v1 2/7] s390x/mm: Implement arch_remove_memory()

David Hildenbrand
2019-04-26T09:11:24Z

On 24.04.19 12:25, David Hildenbrand wrote:
> Will come in handy when wanting to handle errors after
> arch_add_memory().
>
> 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 31b1071315d7..2636d62df04e 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -237,12 +237,13 @@ 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;
> +
> + vmem_remove_mapping(start, size);
> + zone = page_zone(pfn_to_page(start_pfn));
> + __remove_pages(zone, start_pfn, nr_pages, altmap);

I guess the correct way is to remove the mapping after __remove_pages.
But as the pages should not be touched by anybody, it shouldn't really
matter. Will change when I resend.

> }
> #endif
> #endif /* CONFIG_MEMORY_HOTPLUG */
>

--

Thanks,

David / dhildenb