fix memory hot remove not configured case.

Now, arch dependent code around CONFIG_MEMORY_HOTREMOVE is a mess.
This patch cleans up them. This is against 2.6.23-rc6-mm1.

 - fix compile failure on ia64/ CONFIG_MEMORY_HOTPLUG && !CONFIG_MEMORY_HOTREMOVE case.
 - For !CONFIG_MEMORY_HOTREMOVE, add generic no-op remove_memory(),
   which returns -EINVAL.
 - removed remove_pages() only used in powerpc.
 - removed no-op remove_memory() in i386, sh, sparc64, x86_64.

 - only powerpc returns -ENOSYS at memory hot remove(no-op). changes it
   to return -EINVAL.

Note:
Currently, only ia64 supports CONFIG_MEMORY_HOTREMOVE. I welcome other
archs if there are requirements and testers.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/ia64/mm/init.c

@@ -718,7 +718,7 @@ int arch_add_memory(int nid, u64 start, u64 size)
 
 	return ret;
 }
-
+#ifdef CONFIG_MEMORY_HOTREMOVE
 int remove_memory(u64 start, u64 size)
 {
 	unsigned long start_pfn, end_pfn;
@@ -734,4 +734,5 @@ int remove_memory(u64 start, u64 size)
 	return ret;
 }
 EXPORT_SYMBOL_GPL(remove_memory);
+#endif /* CONFIG_MEMORY_HOTREMOVE */
 #endif

arch/powerpc/mm/mem.c

@@ -129,51 +129,6 @@ int __devinit arch_add_memory(int nid, u64 start, u64 size)
 	return __add_pages(zone, start_pfn, nr_pages);
 }
 
-/*
- * First pass at this code will check to determine if the remove
- * request is within the RMO.  Do not allow removal within the RMO.
- */
-int __devinit remove_memory(u64 start, u64 size)
-{
-	struct zone *zone;
-	unsigned long start_pfn, end_pfn, nr_pages;
-
-	start_pfn = start >> PAGE_SHIFT;
-	nr_pages = size >> PAGE_SHIFT;
-	end_pfn = start_pfn + nr_pages;
-
-	printk("%s(): Attempting to remove memoy in range "
-			"%lx to %lx\n", __func__, start, start+size);
-	/*
-	 * check for range within RMO
-	 */
-	zone = page_zone(pfn_to_page(start_pfn));
-
-	printk("%s(): memory will be removed from "
-			"the %s zone\n", __func__, zone->name);
-
-	/*
-	 * not handling removing memory ranges that
-	 * overlap multiple zones yet
-	 */
-	if (end_pfn > (zone->zone_start_pfn + zone->spanned_pages))
-		goto overlap;
-
-	/* make sure it is NOT in RMO */
-	if ((start < lmb.rmo_size) || ((start+size) < lmb.rmo_size)) {
-		printk("%s(): range to be removed must NOT be in RMO!\n",
-			__func__);
-		goto in_rmo;
-	}
-
-	return __remove_pages(zone, start_pfn, nr_pages);
-
-overlap:
-	printk("%s(): memory range to be removed overlaps "
-		"multiple zones!!!\n", __func__);
-in_rmo:
-	return -1;
-}
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
 void show_mem(void)

arch/sh/mm/init.c

@@ -294,12 +294,6 @@ int arch_add_memory(int nid, u64 start, u64 size)
 }
 EXPORT_SYMBOL_GPL(arch_add_memory);
 
-int remove_memory(u64 start, u64 size)
-{
-	return -EINVAL;
-}
-EXPORT_SYMBOL_GPL(remove_memory);
-
 #ifdef CONFIG_NUMA
 int memory_add_physaddr_to_nid(u64 addr)
 {

arch/sparc64/mm/init.c

@@ -1961,9 +1961,4 @@ void online_page(struct page *page)
 	num_physpages++;
 }
 
-int remove_memory(u64 start, u64 size)
-{
-	return -EINVAL;
-}
-
 #endif /* CONFIG_MEMORY_HOTPLUG */

arch/x86/mm/init_32.c

@@ -735,11 +735,6 @@ int arch_add_memory(int nid, u64 start, u64 size)
 	return __add_pages(zone, start_pfn, nr_pages);
 }
 
-int remove_memory(u64 start, u64 size)
-{
-	return -EINVAL;
-}
-EXPORT_SYMBOL_GPL(remove_memory);
 #endif
 
 struct kmem_cache *pmd_cache;

arch/x86/mm/init_64.c

@@ -474,12 +474,6 @@ int arch_add_memory(int nid, u64 start, u64 size)
 }
 EXPORT_SYMBOL_GPL(arch_add_memory);
 
-int remove_memory(u64 start, u64 size)
-{
-	return -EINVAL;
-}
-EXPORT_SYMBOL_GPL(remove_memory);
-
 #if !defined(CONFIG_ACPI_NUMA) && defined(CONFIG_NUMA)
 int memory_add_physaddr_to_nid(u64 start)
 {

include/linux/memory_hotplug.h

@@ -58,10 +58,9 @@ extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
 extern void online_page(struct page *page);
 /* VM interface that may be used by firmware interface */
 extern int online_pages(unsigned long, unsigned long);
-#ifdef CONFIG_MEMORY_HOTREMOVE
-extern int offline_pages(unsigned long, unsigned long, unsigned long);
 extern void __offline_isolated_pages(unsigned long, unsigned long);
-#endif
+extern int offline_pages(unsigned long, unsigned long, unsigned long);
+
 /* reasonably generic interface to expand the physical pages in a zone  */
 extern int __add_pages(struct zone *zone, unsigned long start_pfn,
 	unsigned long nr_pages);
@@ -171,13 +170,6 @@ static inline int mhp_notimplemented(const char *func)
 }
 
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
-static inline int __remove_pages(struct zone *zone, unsigned long start_pfn,
-	unsigned long nr_pages)
-{
-	printk(KERN_WARNING "%s() called, not yet supported\n", __FUNCTION__);
-	dump_stack();
-	return -ENOSYS;
-}
 
 extern int add_memory(int nid, u64 start, u64 size);
 extern int arch_add_memory(int nid, u64 start, u64 size);

mm/memory_hotplug.c

@@ -555,4 +555,10 @@ int offline_pages(unsigned long start_pfn,
 	undo_isolate_page_range(start_pfn, end_pfn);
 	return ret;
 }
+#else
+int remove_memory(u64 start, u64 size)
+{
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(remove_memory);
 #endif /* CONFIG_MEMORY_HOTREMOVE */