On Wed, Jul 8, 2020 at 7:07 PM Jia He <justin.he@xxxxxxx> wrote: > > numa_off is set unconditionally at the end of dummy_numa_init(), > even with a fake numa node. ACPI detects node id as NUMA_NO_NODE(-1) in > acpi_map_pxm_to_node() because it regards numa_off as turning off the numa > node. Hence dev_dax->target_node is NUMA_NO_NODE on arm64 with fake numa. > > Without this patch, pmem can't be probed as a RAM device on arm64 if SRAT table > isn't present: > $ndctl create-namespace -fe namespace0.0 --mode=devdax --map=dev -s 1g -a 64K > kmem dax0.0: rejecting DAX region [mem 0x240400000-0x2bfffffff] with invalid node: -1 > kmem: probe of dax0.0 failed with error -22 > > This fixes it by using fallback memory_add_physaddr_to_nid() as nid. > > Suggested-by: David Hildenbrand <david@xxxxxxxxxx> > Signed-off-by: Jia He <justin.he@xxxxxxx> > --- > drivers/dax/kmem.c | 21 +++++++++++++-------- > 1 file changed, 13 insertions(+), 8 deletions(-) > > diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c > index 275aa5f87399..218f66057994 100644 > --- a/drivers/dax/kmem.c > +++ b/drivers/dax/kmem.c > @@ -31,22 +31,23 @@ int dev_dax_kmem_probe(struct device *dev) > int numa_node; > int rc; > > + /* Hotplug starting at the beginning of the next block: */ > + kmem_start = ALIGN(res->start, memory_block_size_bytes()); > + > /* > * Ensure good NUMA information for the persistent memory. > * Without this check, there is a risk that slow memory > * could be mixed in a node with faster memory, causing > - * unavoidable performance issues. > + * unavoidable performance issues. Furthermore, fallback node > + * id can be used when numa_node is invalid. > */ > numa_node = dev_dax->target_node; > if (numa_node < 0) { > - dev_warn(dev, "rejecting DAX region %pR with invalid node: %d\n", > - res, numa_node); > - return -EINVAL; > + numa_node = memory_add_physaddr_to_nid(kmem_start); I think this fixup belongs to the core to set a fallback value for dev_dax->target_node. I'm close to having patches to provide a functional phys_addr_to_target_node() for arm64.