mm, hotplug: avoid compiling memory hotremove functions when disabled

__remove_pages() is only necessary for CONFIG_MEMORY_HOTREMOVE.  PowerPC
pseries will return -EOPNOTSUPP if unsupported.

Adding an #ifdef causes several other functions it depends on to also
become unnecessary, which saves in .text when disabled (it's disabled in
most defconfigs besides powerpc, including x86).  remove_memory_block()
becomes static since it is not referenced outside of
drivers/base/memory.c.

Build tested on x86 and powerpc with CONFIG_MEMORY_HOTREMOVE both enabled
and disabled.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 74 insertions, 66 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c916582591eb..60f6daad1076 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -436,6 +436,40 @@ static int __meminit __add_section(int nid, struct zone *zone,
         return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
 }
 
+/*
+ * Reasonably generic function for adding memory.  It is
+ * expected that archs that support memory hotplug will
+ * call this function after deciding the zone to which to
+ * add the new pages.
+ */
+int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
+                        unsigned long nr_pages)
+{
+        unsigned long i;
+        int err = 0;
+        int start_sec, end_sec;
+        /* during initialize mem_map, align hot-added range to section */
+        start_sec = pfn_to_section_nr(phys_start_pfn);
+        end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
+
+        for (i = start_sec; i <= end_sec; i++) {
+                err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
+
+                /*
+                 * EEXIST is finally dealt with by ioresource collision
+                 * check. see add_memory() => register_memory_resource()
+                 * Warning will be printed if there is collision.
+                 */
+                if (err && (err != -EEXIST))
+                        break;
+                err = 0;
+        }
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(__add_pages);
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
 /* find the smallest valid pfn in the range [start_pfn, end_pfn) */
 static int find_smallest_section_pfn(int nid, struct zone *zone,
                                      unsigned long start_pfn,
@@ -658,39 +692,6 @@ static int __remove_section(struct zone *zone, struct mem_section *ms)
         return 0;
 }
 
-/*
- * Reasonably generic function for adding memory.  It is
- * expected that archs that support memory hotplug will
- * call this function after deciding the zone to which to
- * add the new pages.
- */
-int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
-                        unsigned long nr_pages)
-{
-        unsigned long i;
-        int err = 0;
-        int start_sec, end_sec;
-        /* during initialize mem_map, align hot-added range to section */
-        start_sec = pfn_to_section_nr(phys_start_pfn);
-        end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
-
-        for (i = start_sec; i <= end_sec; i++) {
-                err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
-
-                /*
-                 * EEXIST is finally dealt with by ioresource collision
-                 * check. see add_memory() => register_memory_resource()
-                 * Warning will be printed if there is collision.
-                 */
-                if (err && (err != -EEXIST))
-                        break;
-                err = 0;
-        }
-
-        return err;
-}
-EXPORT_SYMBOL_GPL(__add_pages);
-
 /**
  * __remove_pages() - remove sections of pages from a zone
  * @zone: zone from which pages need to be removed
@@ -733,6 +734,7 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
         return ret;
 }
 EXPORT_SYMBOL_GPL(__remove_pages);
+#endif /* CONFIG_MEMORY_HOTREMOVE */
 
 int set_online_page_callback(online_page_callback_t callback)
 {
diff --git a/mm/sparse.c b/mm/sparse.c
index a37be5f9050d..1c91f0d3f6ab 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -620,6 +620,7 @@ static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
 
         vmemmap_free(start, end);
 }
+#ifdef CONFIG_MEMORY_HOTREMOVE
 static void free_map_bootmem(struct page *memmap, unsigned long nr_pages)
 {
         unsigned long start = (unsigned long)memmap;
@@ -627,6 +628,7 @@ static void free_map_bootmem(struct page *memmap, unsigned long nr_pages)
 
         vmemmap_free(start, end);
 }
+#endif /* CONFIG_MEMORY_HOTREMOVE */
 #else
 static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
 {
@@ -664,6 +666,7 @@ static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
                            get_order(sizeof(struct page) * nr_pages));
 }
 
+#ifdef CONFIG_MEMORY_HOTREMOVE
 static void free_map_bootmem(struct page *memmap, unsigned long nr_pages)
 {
         unsigned long maps_section_nr, removing_section_nr, i;
@@ -690,40 +693,9 @@ static void free_map_bootmem(struct page *memmap, unsigned long nr_pages)
                         put_page_bootmem(page);
         }
 }
+#endif /* CONFIG_MEMORY_HOTREMOVE */
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
-static void free_section_usemap(struct page *memmap, unsigned long *usemap)
-{
-        struct page *usemap_page;
-        unsigned long nr_pages;
-
-        if (!usemap)
-                return;
-
-        usemap_page = virt_to_page(usemap);
-        /*
-         * Check to see if allocation came from hot-plug-add
-         */
-        if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
-                kfree(usemap);
-                if (memmap)
-                        __kfree_section_memmap(memmap, PAGES_PER_SECTION);
-                return;
-        }
-
-        /*
-         * The usemap came from bootmem. This is packed with other usemaps
-         * on the section which has pgdat at boot time. Just keep it as is now.
-         */
-
-        if (memmap) {
-                nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
-                        >> PAGE_SHIFT;
-
-                free_map_bootmem(memmap, nr_pages);
-        }
-}
-
 /*
  * returns the number of sections whose mem_maps were properly
  * set.  If this is <=0, then that means that the passed-in
@@ -800,6 +772,39 @@ static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 }
 #endif
 
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static void free_section_usemap(struct page *memmap, unsigned long *usemap)
+{
+        struct page *usemap_page;
+        unsigned long nr_pages;
+
+        if (!usemap)
+                return;
+
+        usemap_page = virt_to_page(usemap);
+        /*
+         * Check to see if allocation came from hot-plug-add
+         */
+        if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
+                kfree(usemap);
+                if (memmap)
+                        __kfree_section_memmap(memmap, PAGES_PER_SECTION);
+                return;
+        }
+
+        /*
+         * The usemap came from bootmem. This is packed with other usemaps
+         * on the section which has pgdat at boot time. Just keep it as is now.
+         */
+
+        if (memmap) {
+                nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
+                        >> PAGE_SHIFT;
+
+                free_map_bootmem(memmap, nr_pages);
+        }
+}
+
 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 {
         struct page *memmap = NULL;
@@ -819,4 +824,5 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
         clear_hwpoisoned_pages(memmap, PAGES_PER_SECTION);
         free_section_usemap(memmap, usemap);
 }
-#endif
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+#endif /* CONFIG_MEMORY_HOTPLUG */