Re: [PATCH v5 5/6] x86/NUMA: Provide a range-to-target_node lookup facility

[Thomas Gleixner]

Dan Williams <dan.j.williams@xxxxxxxxx> writes:

> The DEV_DAX_KMEM facility is a generic mechanism to allow device-dax
> instances, fronting performance-differentiated-memory like pmem, to be
> added to the System RAM pool. The NUMA node for that hot-added memory is
> derived from the device-dax instance's 'target_node' attribute.
>
> Recall that the 'target_node' is the ACPI-PXM-to-node translation for
> memory when it comes online whereas the 'numa_node' attribute of the
> device represents the closest online cpu node.
>
> Presently useful target_node information from the ACPI SRAT is discarded
> with the expectation that "Reserved" memory will never be onlined. Now,
> DEV_DAX_KMEM violates that assumption, there is a need to retain the
> translation. Move, rather than discard, numa_memblk data to a secondary
> array that memory_add_physaddr_to_target_node() may consider at a later
> point in time.
>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: <x86@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Reported-by: kbuild test robot <lkp@xxxxxxxxx>
> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>

Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>