From: KAMEZAWA Hiroyuki <[email protected]>
=====================================================================
| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|
=====================================================================
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 <[email protected]>
Acked-by: Wu Fengguang <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
---
mm/internal.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index 6a697bb..dedb0af 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -62,7 +62,7 @@ extern bool is_free_buddy_page(struct page *page);
*/
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);
}
--
1.7.4.4
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