From ef2b4b95a63a1d23958dcb99eb2c6898eddc87d0 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Fri, 18 Mar 2011 00:16:35 +0100 Subject: mm: PageBuddy and mapcount robustness Change the _mapcount value indicating PageBuddy from -2 to -128 for more robusteness against page_mapcount() undeflows. Use reset_page_mapcount instead of __ClearPageBuddy in bad_page to ignore the previous retval of PageBuddy(). Signed-off-by: Andrea Arcangeli Reported-by: Hugh Dickins Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index bd76256..7945247 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -286,7 +286,7 @@ static void bad_page(struct page *page) /* Don't complain about poisoned pages */ if (PageHWPoison(page)) { - __ClearPageBuddy(page); + reset_page_mapcount(page); /* remove PageBuddy */ return; } @@ -317,7 +317,7 @@ static void bad_page(struct page *page) dump_stack(); out: /* Leave bad fields for debug, except PageBuddy could make trouble */ - __ClearPageBuddy(page); + reset_page_mapcount(page); /* remove PageBuddy */ add_taint(TAINT_BAD_PAGE); } -- cgit v1.1