[PATCH] x86_64: Support memory hotadd without sparsemem

Memory hotadd doesn't need SPARSEMEM, but can be handled by just preallocating
mem_maps. This only needs some untangling of ifdefs to enable the necessary
code even without SPARSEMEM.

Originally from Keith Mannthey, hacked by AK.

Signed-off-by: Andi Kleen <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Andi Kleen

arch/i386/mm/init.c

@@ -651,6 +651,7 @@ void __init mem_init(void)
  * Specifically, in the case of x86, we will always add
  * memory to the highmem for now.
  */
+#ifdef CONFIG_HOTPLUG_MEMORY
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 int add_memory(u64 start, u64 size)
 {
@@ -667,6 +668,7 @@ int remove_memory(u64 start, u64 size)
 	return -EINVAL;
 }
 #endif
+#endif
 
 kmem_cache_t *pgd_cache;
 kmem_cache_t *pmd_cache;

arch/x86_64/kernel/e820.c

@@ -80,7 +80,7 @@ static inline int bad_addr(unsigned long *addrp, unsigned long size)
 	return 0;
 } 
 
-int __init e820_mapped(unsigned long start, unsigned long end, unsigned type) 
+int __meminit e820_mapped(unsigned long start, unsigned long end, unsigned type)
 { 
 	int i;
 	for (i = 0; i < e820.nr_map; i++) { 

arch/x86_64/mm/init.c

@@ -507,9 +507,8 @@ void __init clear_kernel_mapping(unsigned long address, unsigned long size)
 
 /*
  * Memory hotplug specific functions
- * These are only for non-NUMA machines right now.
  */
-#ifdef CONFIG_MEMORY_HOTPLUG
+#if defined(CONFIG_ACPI_HOTPLUG_MEMORY) || defined(CONFIG_ACPI_HOTPLUG_MEMORY_MODULE)
 
 void online_page(struct page *page)
 {
@@ -520,6 +519,39 @@ void online_page(struct page *page)
 	num_physpages++;
 }
 
+#ifndef CONFIG_MEMORY_HOTPLUG
+/*
+ * Memory Hotadd without sparsemem. The mem_maps have been allocated in advance,
+ * just online the pages.
+ */
+int __add_pages(struct zone *z, unsigned long start_pfn, unsigned long nr_pages)
+{
+	int err = -EIO;
+	unsigned long pfn;
+	unsigned long total = 0, mem = 0;
+	for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) {
+		unsigned long addr = pfn << PAGE_SHIFT;
+		if (pfn_valid(pfn) && e820_mapped(addr, addr+1, E820_RAM)) {
+			online_page(pfn_to_page(pfn));
+			err = 0;
+			mem++;
+		}
+		total++;
+	}
+	if (!err) {
+		z->spanned_pages += total;
+		z->present_pages += mem;
+		z->zone_pgdat->node_spanned_pages += total;
+		z->zone_pgdat->node_present_pages += mem;
+	}
+	return err;
+}
+#endif
+
+/*
+ * Memory is added always to NORMAL zone. This means you will never get
+ * additional DMA/DMA32 memory.
+ */
 int add_memory(u64 start, u64 size)
 {
 	struct pglist_data *pgdat = NODE_DATA(0);

drivers/acpi/Kconfig

@@ -329,7 +329,7 @@ config ACPI_CONTAINER
 config ACPI_HOTPLUG_MEMORY
 	tristate "Memory Hotplug"
 	depends on ACPI
-	depends on MEMORY_HOTPLUG
+	depends on MEMORY_HOTPLUG || X86_64
 	default n
 	help
 	  This driver adds supports for ACPI Memory Hotplug.  This driver

include/linux/init.h

@@ -245,7 +245,8 @@ void __init parse_early_param(void);
 #define __cpuexitdata	__exitdata
 #endif
 
-#ifdef CONFIG_MEMORY_HOTPLUG
+#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_ACPI_HOTPLUG_MEMORY) \
+	|| defined(CONFIG_ACPI_HOTPLUG_MEMORY_MODULE)
 #define __meminit
 #define __meminitdata
 #define __memexit

include/linux/memory_hotplug.h

@@ -58,8 +58,6 @@ extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
 /* need some defines for these for archs that don't support it */
 extern void online_page(struct page *page);
 /* VM interface that may be used by firmware interface */
-extern int add_memory(u64 start, u64 size);
-extern int remove_memory(u64 start, u64 size);
 extern int online_pages(unsigned long, unsigned long);
 
 /* reasonably generic interface to expand the physical pages in a zone  */
@@ -92,11 +90,6 @@ static inline int mhp_notimplemented(const char *func)
 	return -ENOSYS;
 }
 
-static inline int __add_pages(struct zone *zone, unsigned long start_pfn,
-	unsigned long nr_pages)
-{
-	return mhp_notimplemented(__FUNCTION__);
-}
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
 static inline int __remove_pages(struct zone *zone, unsigned long start_pfn,
 	unsigned long nr_pages)
@@ -105,4 +98,11 @@ static inline int __remove_pages(struct zone *zone, unsigned long start_pfn,
 	dump_stack();
 	return -ENOSYS;
 }
+
+#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_ACPI_HOTPLUG_MEMORY) \
+	|| defined(CONFIG_ACPI_HOTPLUG_MEMORY_MODULE)
+extern int add_memory(u64 start, u64 size);
+extern int remove_memory(u64 start, u64 size);
+#endif
+
 #endif /* __LINUX_MEMORY_HOTPLUG_H */