From: Rafael J. Wysocki Date: Wed, 6 Jul 2011 18:15:23 +0000 (+0200) Subject: PM / Hibernate: Fix free_unnecessary_pages() X-Git-Tag: v2.6.33.16~8 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=386f12d6c880e3c7b9a31da1c7b5cca3500470d0;p=karo-tx-linux.git PM / Hibernate: Fix free_unnecessary_pages() commit 4d4cf23cdde2f8f9324f5684a7f349e182039529 upstream. There is a bug in free_unnecessary_pages() that causes it to attempt to free too many pages in some cases, which triggers the BUG_ON() in memory_bm_clear_bit() for copy_bm. Namely, if count_data_pages() is initially greater than alloc_normal, we get to_free_normal equal to 0 and "save" greater from 0. In that case, if the sum of "save" and count_highmem_pages() is greater than alloc_highmem, we subtract a positive number from to_free_normal. Hence, since to_free_normal was 0 before the subtraction and is an unsigned int, the result is converted to a huge positive number that is used as the number of pages to free. Fix this bug by checking if to_free_normal is actually greater than or equal to the number we're going to subtract from it. Signed-off-by: Rafael J. Wysocki Reported-and-tested-by: Matthew Garrett Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 944972e48f8b..356f48722ef1 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -1193,7 +1193,11 @@ static void free_unnecessary_pages(void) to_free_highmem = alloc_highmem - save; } else { to_free_highmem = 0; - to_free_normal -= save - alloc_highmem; + save -= alloc_highmem; + if (to_free_normal > save) + to_free_normal -= save; + else + to_free_normal = 0; } memory_bm_position_reset(©_bm);