[PATCH] memory hotadd fixes: find_next_system_ram catch range fix

find_next_system_ram() is used to find available memory resource at onlining
newly added memory.  This patch fixes following problem.

find_next_system_ram() cannot catch this case.

Resource:      (start)-------------(end)
Section :                (start)-------------(end)
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Keith Mannthey <kmannth@gmail.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/resource.c

@@ -244,6 +244,7 @@ int find_next_system_ram(struct resource *res)
 
 	start = res->start;
 	end = res->end;
+	BUG_ON(start >= end);
 
 	read_lock(&resource_lock);
 	for (p = iomem_resource.child; p ; p = p->sibling) {
@@ -254,7 +255,7 @@ int find_next_system_ram(struct resource *res)
 			p = NULL;
 			break;
 		}
-		if (p->start >= start)
+		if ((p->end >= start) && (p->start < end))
 			break;
 	}
 	read_unlock(&resource_lock);

mm/memory_hotplug.c

@@ -163,7 +163,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 	res.flags = IORESOURCE_MEM; /* we just need system ram */
 	section_end = res.end;
 
-	while (find_next_system_ram(&res) >= 0) {
+	while ((res.start < res.end) && (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);