2.6.36-stable review patch. If anyone has any objections, please let us know.
------------------
From: KAMEZAWA Hiroyuki <kamezawa.hir...@jp.fujitsu.com>
commit 572438f9b52236bd8938b1647cc15e027d27ef55 upstream.
page_order() is called by memory hotplug's user interface to check the
section is removable or not. (is_mem_section_removable())
It calls page_order() withoug holding zone->lock.
So, even if the caller does
if (PageBuddy(page))
ret = page_order(page) ...
The caller may hit BUG_ON().
For fixing this, there are 2 choices.
1. add zone->lock.
2. remove BUG_ON().
is_mem_section_removable() is used for some "advice" and doesn't need to
be 100% accurate. This is_removable() can be called via user program..
We don't want to take this important lock for long by user's request. So,
this patch removes BUG_ON().
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hir...@jp.fujitsu.com>
Acked-by: Wu Fengguang <fengguang...@intel.com>
Acked-by: Michal Hocko <mho...@suse.cz>
Acked-by: Mel Gorman <m...@csn.ul.ie>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@suse.de>
---
mm/internal.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -62,7 +62,7 @@ extern bool is_free_buddy_page(struct pa
*/
static inline unsigned long page_order(struct page *page)
{
- VM_BUG_ON(!PageBuddy(page));
+ /* PageBuddy() must be checked by the caller */
return page_private(page);
}
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