mm: ZONE_DEVICE depends on SPARSEMEM_VMEMMAP

The primary use case for devm_memremap_pages() is to allocate an memmap
array from persistent memory.  That capabilty requires vmem_altmap which
requires SPARSEMEM_VMEMMAP.

Also, without SPARSEMEM_VMEMMAP the addition of ZONE_DEVICE expands
ZONES_WIDTH and triggers the:

"Unfortunate NUMA and NUMA Balancing config, growing page-frame for
last_cpupid."

...warning in mm/memory.c.  SPARSEMEM_VMEMMAP=n && ZONE_DEVICE=y is not
a configuration we should worry about supporting.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/Kconfig b/mm/Kconfig
index 520dae6..05efa6a 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -653,6 +653,7 @@ config ZONE_DEVICE
        bool "Device memory (pmem, etc...) hotplug support" if EXPERT
        depends on MEMORY_HOTPLUG
        depends on MEMORY_HOTREMOVE
+       depends on SPARSEMEM_VMEMMAP
        depends on X86_64 #arch_add_memory() comprehends device memory
 
        help