powerpc: Fix memory hotplug with sparse vmemmap

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 <nfont@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org> [v3.9+]

3 files changed, 14 insertions, 1 deletions

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index d0cd9e4c6837..8ed035d2edb5 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -300,5 +300,9 @@ void vmemmap_free(unsigned long start, unsigned long end)
 {
 }
 
+void register_page_bootmem_memmap(unsigned long section_nr,
+                                  struct page *start_page, unsigned long size)
+{
+}
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 1cf9c5b67f24..3fa93dc7fe75 100644
--- a/arch/powerpc/mm/mem.c
+++ b/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();
diff --git a/mm/Kconfig b/mm/Kconfig
index 026771a9b097..394838f489eb 100644
--- a/mm/Kconfig
+++ b/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