I wonder this should be for stable tree...but want to hear opinions before.
==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
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.hiroyu@xxxxxxxxxxxxxx>
---
mm/internal.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Index: mmotm-1024/mm/internal.h
===================================================================
--- mmotm-1024.orig/mm/internal.h
+++ mmotm-1024/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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