[PATCH 03/21] x86, acpi, numa, mem-hotplug: Introduce MEMBLK_HOTPLUGGABLE to reserve hotpluggable memory.

[Tang Chen]

Pages used by the kernel cannot be migrated. As a result, hotpluggable
memory used by the kernel cannot be hot-removed. So for memory
hotplug users, the kernel should not use hotpluggable memory.

Since now we have flags in memblock, we introduce a MEMBLK_HOTPLUGGABLE
flag to mark hotpluggable memory. At the early time, we use memblock to
reserve hotpluggable memory, and mark it with MEMBLK_HOTPLUGGABLE flag.
When the system is up, we free these memory with MEMBLK_HOTPLUGGABLE
flag to the buddy, and arrange them into ZONE_MOVABLE. In this way, the
kernel won't be able to use it.

This patch introduces MEMBLK_HOTPLUGGABLE flag, and an API to reserve
memory with MEMBLK_HOTPLUGGABLE flag. This is a preparation for the
coming patches.

Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
---
 include/linux/memblock.h |    2 ++
 mm/memblock.c            |    6 ++++++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 93f3453..90b49ee 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -21,6 +21,7 @@
 
 /* Definition of memblock flags. */
 #define MEMBLK_FLAGS_DEFAULT	0x0	/* default flag */
+#define MEMBLK_HOTPLUGGABLE	0x1	/* hotpluggable region */
 
 struct memblock_region {
 	phys_addr_t base;
@@ -61,6 +62,7 @@ int memblock_add(phys_addr_t base, phys_addr_t size);
 int memblock_remove(phys_addr_t base, phys_addr_t size);
 int memblock_free(phys_addr_t base, phys_addr_t size);
 int memblock_reserve(phys_addr_t base, phys_addr_t size);
+int memblock_reserve_hotpluggable(phys_addr_t base, phys_addr_t size, int nid);
 void memblock_trim_memory(phys_addr_t align);
 
 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
diff --git a/mm/memblock.c b/mm/memblock.c
index 9e871e9..73fe62d 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -586,6 +586,12 @@ int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
 				       MEMBLK_FLAGS_DEFAULT);
 }
 
+int __init_memblock memblock_reserve_hotpluggable(phys_addr_t base,
+						  phys_addr_t size, int nid)
+{
+	return memblock_reserve_region(base, size, nid, MEMBLK_HOTPLUGGABLE);
+}
+
 /**
  * __next_free_mem_range - next function for for_each_free_mem_range()
  * @idx: pointer to u64 loop variable
-- 
1.7.1

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