[PATCH] memory hotadd fixes: find_next_system_ram catch range fix

hkamezawa · Linus Torvalds · commit 58c1b5b07907 · 2006-08-06T08:57:48.000-07:00
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 &lt;kamezawa.hiroyu@jp.fujitsu.com&gt;
Cc: Keith Mannthey &lt;kmannth@gmail.com&gt;
Cc: Yasunori Goto &lt;y-goto@jp.fujitsu.com&gt;
Cc: Dave Hansen &lt;haveblue@us.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@osdl.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@osdl.org&gt;
diff --git a/kernel/resource.c b/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);
diff --git a/mm/memory_hotplug.c b/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);

Original file line number	Diff line number	Diff line change
`@@ -244,6 +244,7 @@ int find_next_system_ram(struct resource *res)`
`244`	`244`
`245`	`245`	`start = res->start;`
`246`	`246`	`end = res->end;`
	`247`	`+ BUG_ON(start >= end);`
`247`	`248`
`248`	`249`	`read_lock(&resource_lock);`
`249`	`250`	`for (p = iomem_resource.child; p ; p = p->sibling) {`
`@@ -254,7 +255,7 @@ int find_next_system_ram(struct resource *res)`
`254`	`255`	`p = NULL;`
`255`	`256`	`break;`
`256`	`257`	`}`
`257`		`- if (p->start >= start)`
	`258`	`+ if ((p->end >= start) && (p->start < end))`
`258`	`259`	`break;`
`259`	`260`	`}`
`260`	`261`	`read_unlock(&resource_lock);`