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

[akpm@linux-foundation.org: fix warning]
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 6 insertions, 0 deletions

diff --git a/mm/memblock.c b/mm/memblock.c
index 70fad0c0dafb..6ecb0d937fb5 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -816,6 +816,10 @@ 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;
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 7ed58602e71b..7c7ab32ee503 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -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, -1);
+
         for_each_free_mem_range(i, NUMA_NO_NODE, &start, &end, NULL)
                 count += __free_memory_core(start, end);