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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>
This commit is contained in:
Dan Williams 2016-03-17 14:19:58 -07:00 committed by Linus Torvalds
parent 0e8fb9312f
commit 99490f16f8
1 changed files with 1 additions and 0 deletions
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mm/Kconfig
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@ -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
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