Mel, As of commit 8a942fdea560d4ac0e9d9fabcd5201ad20e0c382 (mm: meminit: make __early_pfn_to_nid SMP-safe and introduce meminit_pfn_in_nid) vmemmap_verify() will BUG_ON() during memory hotplug because of its use of early_pfn_to_nid(). Previously, it would have reported bogus (or failed to report valid) warnings. I believe this does not affect memory hotplug on most x86 systems because vmemmap_populate() would normally call vmemmap_populate_hugepages() which avoids calling vmemmap_verify() in the common case (no existing mappings covering the new area). I'm triggering the early_pfn_to_nid() BUG_ON() with the Xen balloon driver in a PV guest which will always call vmemmap_populate_basepages() (since Xen PV guests lack superpage support). Not really sure what the best way to resolve this is. Presumably vmmemmap_verify() needs to switch to using pfn_to_nid() after the initial initialization but there doesn't appear to be anything suitable to distinguish between the early and hotplug cases. David -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>