When vmemmap_populate() allocates space for the memmap it does so in 2MB sized chunks. The libnvdimm-pfn driver incorrectly accounts for this when the alignment of the device is set to 4K. When this happens we trigger memory allocation failures in altmap_alloc_block_buf() and trigger warnings of the form: WARNING: CPU: 0 PID: 3376 at arch/x86/mm/init_64.c:656 arch_add_memory+0xe4/0xf0 [..] Call Trace: dump_stack+0x86/0xc3 __warn+0xcb/0xf0 warn_slowpath_null+0x1d/0x20 arch_add_memory+0xe4/0xf0 devm_memremap_pages+0x29b/0x4e0 Fixes: 315c562536c4 ("libnvdimm, pfn: add 'align' attribute, default to HPAGE_SIZE") Cc: <stable@vger.kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>