Re: [PATCH] x86/mm: Fix phys_to_target_node() export

[Dan Williams <dan.j.williams@intel.com>]

On Thu, Oct 29, 2020 at 7:29 PM Dan Williams <dan.j.williams@intel.com> wrote:
>
> The core-mm has a default __weak implementation of phys_to_target_node()
> when the architecture does not override it. That symbol is exported
> for modules. However, while the export in mm/memory_hotplug.c exported
> the symbol in the configuration cases of:
>
>         CONFIG_NUMA_KEEP_MEMINFO=y
>         CONFIG_MEMORY_HOTPLUG=y
>
> ...and:
>
>         CONFIG_NUMA_KEEP_MEMINFO=n
>         CONFIG_MEMORY_HOTPLUG=y
>
> ...it failed to export the symbol in the case of:
>
>         CONFIG_NUMA_KEEP_MEMINFO=y
>         CONFIG_MEMORY_HOTPLUG=n
>
> Always export the symbol from the CONFIG_NUMA_KEEP_MEMINFO section of
> arch/x86/mm/numa.c, and teach mm/memory_hotplug.c to optionally export
> in case arch/x86/mm/numa.c has already performed the export.
>
> The dependency on NUMA_KEEP_MEMINFO for DEV_DAX_HMEM_DEVICES is invalid
> now that the symbol is properly exported in all combinations of
> CONFIG_NUMA_KEEP_MEMINFO and CONFIG_MEMORY_HOTPLUG. Note that in the
> CONFIG_NUMA=n case no export is needed since their is a dummy static
> inline implementation of phys_to_target_node() in that case.
>
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Reported-by: Thomas Gleixner <tglx@linutronix.de>
> Reported-by: kernel test robot <lkp@intel.com>
> Fixes: a035b6bf863e ("mm/memory_hotplug: introduce default phys_to_target_node() implementation")
> Cc: Joao Martins <joao.m.martins@oracle.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: x86@kernel.org
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Thomas, do you want to ack this so Andrew can pick it up, or I can
take it through as a device-dax update, but either way the diffstat
warrants x86 + mm acks.