On Wed, Jul 08, 2020 at 09:21:25AM +0200, David Hildenbrand wrote: > On 08.07.20 07:27, Mike Rapoport wrote: > > On Tue, Jul 07, 2020 at 03:05:48PM -0700, Dan Williams wrote: > >> On Tue, Jul 7, 2020 at 11:01 AM Mike Rapoport <r...@linux.ibm.com> wrote: > >>> > >>> On Tue, Jul 07, 2020 at 02:26:08PM +0200, David Hildenbrand wrote: > >>>> On 07.07.20 14:13, Mike Rapoport wrote: > >>>>> On Tue, Jul 07, 2020 at 01:54:54PM +0200, Michal Hocko wrote: > >>>>>> On Tue 07-07-20 13:59:15, Jia He wrote: > >>>>>>> This exports memory_add_physaddr_to_nid() for module driver to use. > >>>>>>> > >>>>>>> memory_add_physaddr_to_nid() is a fallback option to get the nid in > >>>>>>> case > >>>>>>> NUMA_NO_NID is detected. > >>>>>>> > >>>>>>> Suggested-by: David Hildenbrand <da...@redhat.com> > >>>>>>> Signed-off-by: Jia He <justin...@arm.com> > >>>>>>> --- > >>>>>>> arch/arm64/mm/numa.c | 5 +++-- > >>>>>>> 1 file changed, 3 insertions(+), 2 deletions(-) > >>>>>>> > >>>>>>> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c > >>>>>>> index aafcee3e3f7e..7eeb31740248 100644 > >>>>>>> --- a/arch/arm64/mm/numa.c > >>>>>>> +++ b/arch/arm64/mm/numa.c > >>>>>>> @@ -464,10 +464,11 @@ void __init arm64_numa_init(void) > >>>>>>> > >>>>>>> /* > >>>>>>> * We hope that we will be hotplugging memory on nodes we already > >>>>>>> know about, > >>>>>>> - * such that acpi_get_node() succeeds and we never fall back to > >>>>>>> this... > >>>>>>> + * such that acpi_get_node() succeeds. But when SRAT is not present, > >>>>>>> the node > >>>>>>> + * id may be probed as NUMA_NO_NODE by acpi, Here provide a fallback > >>>>>>> option. > >>>>>>> */ > >>>>>>> int memory_add_physaddr_to_nid(u64 addr) > >>>>>>> { > >>>>>>> - pr_warn("Unknown node for memory at 0x%llx, assuming node 0\n", > >>>>>>> addr); > >>>>>>> return 0; > >>>>>>> } > >>>>>>> +EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid); > >>>>>> > >>>>>> Does it make sense to export a noop function? Wouldn't make more sense > >>>>>> to simply make it static inline somewhere in a header? I haven't > >>>>>> checked > >>>>>> whether there is an easy way to do that sanely bu this just hit my > >>>>>> eyes. > >>>>> > >>>>> We'll need to either add a CONFIG_ option or arch specific callback to > >>>>> make both non-empty (x86, powerpc, ia64) and empty (arm64, sh) > >>>>> implementations coexist ... > >>>> > >>>> Note: I have a similar dummy (return 0) patch for s390x lying around > >>>> here. > >>> > >>> Then we'll call it a tie - 3:3 ;-) > >> > >> So I'd be happy to jump on the train of people wanting to export the > >> ARM stub for this (and add a new ARM stub for phys_to_target_node()), > >> but Will did have a plausibly better idea that I have been meaning to > >> circle back to: > >> > >> http://lore.kernel.org/r/20200325111039.GA32109@willie-the-truck > >> > >> ...i.e. iterate over node data to do the lookup. This would seem to > >> work generically for multiple archs unless I am missing something? > > IIRC, only memory assigned to/onlined to a ZONE is represented in the > pgdat node span. E.g., not offline memory blocks. > > Esp., when hotplugging + onlining consecutive memory, there won't really > be any intersections in most cases if I am not wrong. It would not be > "intersection" but rather "closest fit". > > With overlapping nodes it's even more unclear. Which one to pick? > > > > > I think it would work on arm64, power and, most propbably on s390 > > With only a single dummy node I guess it should work (searching when > there is only a single node does not make too much sense). > > > (David?), but not on x86. x86 does not have reserved memory in pgdat, > > it's never memblock_add()'ed (see e820__memblock_setup()). > > Can you enlighten me why that is relevant for the memory hotplug path? > (or is it just a general comment to make the function as accurate as > possible for all addresses?)
phys_to_target_node() on x86 falls back to numa_reserved_meminfo which holds memory that is never listed in a node. > -- > Thanks, > > David / dhildenb > -- Sincerely yours, Mike.