mm, memory_hotplug: provide a more generic restrictions for memory hotplug

arch_add_memory, __add_pages take a want_memblock which controls whether
the newly added memory should get the sysfs memblock user API (e.g.
ZONE_DEVICE users do not want/need this interface).  Some callers even
want to control where do we allocate the memmap from by configuring
altmap.

Add a more generic hotplug context for arch_add_memory and __add_pages.
struct mhp_restrictions contains flags which contains additional features
to be enabled by the memory hotplug (MHP_MEMBLOCK_API currently) and
altmap for alternative memmap allocator.

This patch shouldn't introduce any functional change.

[akpm@linux-foundation.org: build fix]
Link: http://lkml.kernel.org/r/20190408082633.2864-3-osalvador@suse.de
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index ef82312..ef32d48 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1065,8 +1065,8 @@ int p4d_free_pud_page(p4d_t *p4d, unsigned long addr)
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
-		    bool want_memblock)
+int arch_add_memory(int nid, u64 start, u64 size,
+			struct mhp_restrictions *restrictions)
 {
 	int flags = 0;
 
@@ -1077,6 +1077,6 @@ int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
 			     size, PAGE_KERNEL, __pgd_pgtable_alloc, flags);
 
 	return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
-			   altmap, want_memblock);
+			   restrictions);
 }
 #endif