From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

This patch allows hot-add memory which is not aligned to section.

Now, hot-added memory has to be aligned to section size.  Considering big
section sized archs, this is not useful.

When hot-added memory is registerd as iomem resoruce by iomem resource
patch, we can make use of that information to detect valid memory range.

Note: With this, not-aligned memory can be registerd. To allow hot-add
      memory with holes, we have to do more work around add_memory().
      (It doesn't allows add memory to already existing mem section.)


Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 include/linux/ioport.h |    3 +++
 kernel/resource.c      |   38 ++++++++++++++++++++++++++++++++++++++
 mm/memory_hotplug.c    |   28 ++++++++++++++++++++++++----
 3 files changed, 65 insertions(+), 4 deletions(-)

diff -puN include/linux/ioport.h~catch-valid-mem-range-at-onlining-memory include/linux/ioport.h
--- devel/include/linux/ioport.h~catch-valid-mem-range-at-onlining-memory	2006-06-09 15:21:48.000000000 -0700
+++ devel-akpm/include/linux/ioport.h	2006-06-09 15:21:48.000000000 -0700
@@ -105,6 +105,9 @@ extern int allocate_resource(struct reso
 int adjust_resource(struct resource *res, resource_size_t start,
 		    resource_size_t size);
 
+/* get registered SYSTEM_RAM resources in specified area */
+extern int find_next_system_ram(struct resource *res);
+
 /* Convenience shorthand with allocation */
 #define request_region(start,n,name)	__request_region(&ioport_resource, (start), (n), (name))
 #define request_mem_region(start,n,name) __request_region(&iomem_resource, (start), (n), (name))
diff -puN kernel/resource.c~catch-valid-mem-range-at-onlining-memory kernel/resource.c
--- devel/kernel/resource.c~catch-valid-mem-range-at-onlining-memory	2006-06-09 15:21:48.000000000 -0700
+++ devel-akpm/kernel/resource.c	2006-06-09 15:21:48.000000000 -0700
@@ -241,6 +241,44 @@ int release_resource(struct resource *ol
 
 EXPORT_SYMBOL(release_resource);
 
+#ifdef CONFIG_MEMORY_HOTPLUG
+/*
+ * Finds the lowest memory reosurce exists within [res->start.res->end)
+ * the caller must specify res->start, res->end, res->flags.
+ * If found, returns 0, res is overwritten, if not found, returns -1.
+ */
+int find_next_system_ram(struct resource *res)
+{
+	resource_size_t start, end;
+	struct resource *p;
+
+	BUG_ON(!res);
+
+	start = res->start;
+	end = res->end;
+
+	read_lock(&resource_lock);
+	for (p = iomem_resource.child; p ; p = p->sibling) {
+		/* system ram is just marked as IORESOURCE_MEM */
+		if (p->flags != res->flags)
+			continue;
+		if (p->start > end) {
+			p = NULL;
+			break;
+		}
+		if (p->start >= start)
+			break;
+	}
+	read_unlock(&resource_lock);
+	if (!p)
+		return -1;
+	/* copy data */
+	res->start = p->start;
+	res->end = p->end;
+	return 0;
+}
+#endif
+
 /*
  * Find empty slot in the resource tree given range and alignment.
  */
diff -puN mm/memory_hotplug.c~catch-valid-mem-range-at-onlining-memory mm/memory_hotplug.c
--- devel/mm/memory_hotplug.c~catch-valid-mem-range-at-onlining-memory	2006-06-09 15:21:48.000000000 -0700
+++ devel-akpm/mm/memory_hotplug.c	2006-06-09 15:21:48.000000000 -0700
@@ -127,6 +127,9 @@ int online_pages(unsigned long pfn, unsi
 	unsigned long i;
 	unsigned long flags;
 	unsigned long onlined_pages = 0;
+	struct resource res;
+	u64 section_end;
+	unsigned long start_pfn;
 	struct zone *zone;
 	int need_zonelists_rebuild = 0;
 
@@ -149,10 +152,27 @@ int online_pages(unsigned long pfn, unsi
 	if (!populated_zone(zone))
 		need_zonelists_rebuild = 1;
 
-	for (i = 0; i < nr_pages; i++) {
-		struct page *page = pfn_to_page(pfn + i);
-		online_page(page);
-		onlined_pages++;
+	res.start = (u64)pfn << PAGE_SHIFT;
+	res.end = res.start + ((u64)nr_pages << PAGE_SHIFT) - 1;
+	res.flags = IORESOURCE_MEM; /* we just need system ram */
+	section_end = res.end;
+
+	while (find_next_system_ram(&res) >= 0) {
+		start_pfn = (unsigned long)(res.start >> PAGE_SHIFT);
+		nr_pages = (unsigned long)
+                           ((res.end + 1 - res.start) >> PAGE_SHIFT);
+
+		if (PageReserved(pfn_to_page(start_pfn))) {
+			/* this region's page is not onlined now */
+			for (i = 0; i < nr_pages; i++) {
+				struct page *page = pfn_to_page(start_pfn + i);
+				online_page(page);
+				onlined_pages++;
+			}
+		}
+
+		res.start = res.end + 1;
+		res.end = section_end;
 	}
 	zone->present_pages += onlined_pages;
 	zone->zone_pgdat->node_present_pages += onlined_pages;
_