Subject: [PATCH] Correct memory hotplug for ppc with sparse vmemmap

From: Nathan Fontenot <[email-masked]>
Date: Fri, 27 Sep 2013 10:18:09 -0500

Previous commit 46723bfa540... introduced a new config option
HAVE_BOOTMEM_INFO_NODE that ended up breaking memory hot-remove for ppc
when sparse vmemmap is not defined.

This patch defines HAVE_BOOTMEM_INFO_NODE for ppc and adds the call to
register_page_bootmem_info_node. Without this we get a BUG_ON for memory
hot remove in put_page_bootmem().

This also adds a stub for register_page_bootmem_memmap to allow ppc to build
with sparse vmemmap defined. Leaving this as a stub is fine since the same
vmemmap addresses are also handled in vmemmap_populate and as such are
properly mapped.

Signed-off-by: Nathan Fontenot <[email-masked]>
---
 arch/powerpc/mm/init_64.c |    4 ++++
 arch/powerpc/mm/mem.c     |    9 +++++++++
 mm/Kconfig                |    2 +-
 3 files changed, 14 insertions(+), 1 deletion(-)

Index: powerpc/arch/powerpc/mm/init_64.c
===================================================================
--- powerpc.orig/arch/powerpc/mm/init_64.c
+++ powerpc/arch/powerpc/mm/init_64.c
@@ -300,5 +300,9 @@ void vmemmap_free(unsigned long start, u
 {
 }

+void register_page_bootmem_memmap(unsigned long section_nr,
+				  struct page *start_page, unsigned long size)
+{
+}
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */

Index: powerpc/arch/powerpc/mm/mem.c
===================================================================
--- powerpc.orig/arch/powerpc/mm/mem.c
+++ powerpc/arch/powerpc/mm/mem.c
@@ -297,12 +297,21 @@ void __init paging_init(void)
 }
 #endif /* ! CONFIG_NEED_MULTIPLE_NODES */

+static void __init register_page_bootmem_info(void)
+{
+	int i;
+
+	for_each_online_node(i)
+		register_page_bootmem_info_node(NODE_DATA(i));
+}
+
 void __init mem_init(void)
 {
 #ifdef CONFIG_SWIOTLB
 	swiotlb_init(0);
 #endif

+	register_page_bootmem_info();
 	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 	set_max_mapnr(max_pfn);
 	free_all_bootmem();
Index: powerpc/mm/Kconfig
===================================================================
--- powerpc.orig/mm/Kconfig
+++ powerpc/mm/Kconfig
@@ -183,7 +183,7 @@ config MEMORY_HOTPLUG_SPARSE
 config MEMORY_HOTREMOVE
 	bool "Allow for memory hot remove"
 	select MEMORY_ISOLATION
-	select HAVE_BOOTMEM_INFO_NODE if X86_64
+	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
 	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
 	depends on MIGRATION