mem-hotplug: let memblock skip the hotpluggable memory regions in __next_mem_range()

Let memblock skip the hotpluggable memory regions in __next_mem_range(), it is used to to prevent memblock from allocating hotpluggable memory for the kernel at early time. The code is the same as __next_mem_range_rev().

Clear hotpluggable flag before releasing free pages to the buddy allocator. If we don't clear hotpluggable flag in free_low_memory_core_early(), the memory which marked hotpluggable flag will not free to buddy allocator. Because __next_mem_range() will skip them.

free_low_memory_core_early
for_each_free_mem_range
for_each_mem_range
__next_mem_range

---
 mm/memblock.c  |    4 ++++
 mm/nobootmem.c |    2 ++
 2 files changed, 6 insertions(+), 0 deletions(-)

index 6d2f219..5090050 100644
@@ -817,6 +817,10 @@ void __init_memblock __next_mem_range(u64 *idx, int nid,
 		if (nid != NUMA_NO_NODE && nid != m_nid)
 			continue;
 
+		/* skip hotpluggable memory regions if needed */
+		if (movable_node_is_enabled() && memblock_is_hotpluggable(m))
+			continue;
+
 		if (!type_b) {
 			if (out_start)
 				*out_start = m_start;

index 7ed5860..03de286 100644
@@ -119,6 +119,8 @@ static unsigned long __init free_low_memory_core_early(void)
 	phys_addr_t start, end;
 	u64 i;
 
+	memblock_clear_hotplug(0, ULLONG_MAX);
+
 	for_each_free_mem_range(i, NUMA_NO_NODE, &start, &end, NULL)
 		count += __free_memory_core(start, end);
 

-- 1.7.1

.