github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-08 22:52:35 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

mm: fix is_mem_section_removable() page_order BUG_ON check

Browse Source 
commit 572438f9b5 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.hiroyu@jp.fujitsu.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
KAMEZAWA Hiroyuki 2010-10-26 14:22:08 -07:00 committed by Greg Kroah-Hartman
parent 76faf361cd
commit e36e20486e
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
mm/internal.h
View File

@ -59,7 +59,7 @@ extern void prep_compound_page(struct page *page, unsigned long order);
*/
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);
}