On 03/05/2016 01:42 AM, Dan Williams wrote:
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.
Some if the ifdefs around to_vmem_altmap() could now be simplified, but that can also be done later...
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. Reported-by: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
--- mm/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/Kconfig b/mm/Kconfig index 664fa2416909..b95322ba542b 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -654,6 +654,7 @@ 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
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