On Tue, Jul 7, 2020 at 11:01 AM Mike Rapoport [off-list ref] wrote:

On Tue, Jul 07, 2020 at 02:26:08PM +0200, David Hildenbrand wrote:

quoted

On 07.07.20 14:13, Mike Rapoport wrote:

quoted

On Tue, Jul 07, 2020 at 01:54:54PM +0200, Michal Hocko wrote:

quoted

On Tue 07-07-20 13:59:15, Jia He wrote:

quoted

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 <redacted>
Signed-off-by: Jia He <redacted>
---
 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 (local)

...i.e. iterate over node data to do the lookup. This would seem to
work generically for multiple archs unless I am missing something?

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