memcg limit and usage values are stored in res_counter, as 64-bit
numbers, even on 32-bit machines. The "free" variable in
memcg_hierarchical_free_pages() stores the difference between two
64-bit numbers (limit - current_usage), and thus should be stored
in a 64-bit local rather than a machine defined unsigned long.
Reported-by: Daisuke Nishimura <[email protected]>
Signed-off-by: Greg Thelen <[email protected]>
---
mm/memcontrol.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 35870f9..d8a06d6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1343,7 +1343,8 @@ static long mem_cgroup_local_page_stat(struct mem_cgroup *mem,
static unsigned long
memcg_hierarchical_free_pages(struct mem_cgroup *mem)
{
- unsigned long free, min_free;
+ u64 free;
+ unsigned long min_free;
min_free = global_page_state(NR_FREE_PAGES);
@@ -1351,7 +1352,7 @@ memcg_hierarchical_free_pages(struct mem_cgroup *mem)
free = (res_counter_read_u64(&mem->res, RES_LIMIT) -
res_counter_read_u64(&mem->res, RES_USAGE)) >>
PAGE_SHIFT;
- min_free = min(min_free, free);
+ min_free = min((u64)min_free, free);
mem = parent_mem_cgroup(mem);
}
--
1.7.3.1
On Tue, Nov 09, 2010 at 12:54:13AM -0800, Greg Thelen wrote:
> memcg limit and usage values are stored in res_counter, as 64-bit
> numbers, even on 32-bit machines. The "free" variable in
> memcg_hierarchical_free_pages() stores the difference between two
> 64-bit numbers (limit - current_usage), and thus should be stored
> in a 64-bit local rather than a machine defined unsigned long.
It is converted to pages before the assignment, but even that might
overflow on 32-bit if the difference is sufficiently large (> 1<<44).
> Reported-by: Daisuke Nishimura <[email protected]>
> Signed-off-by: Greg Thelen <[email protected]>
Reviewed-by: Johannes Weiner <[email protected]>
On Tue, 9 Nov 2010 00:54:13 -0800
Greg Thelen <[email protected]> wrote:
> memcg limit and usage values are stored in res_counter, as 64-bit
> numbers, even on 32-bit machines. The "free" variable in
> memcg_hierarchical_free_pages() stores the difference between two
> 64-bit numbers (limit - current_usage), and thus should be stored
> in a 64-bit local rather than a machine defined unsigned long.
>
> Reported-by: Daisuke Nishimura <[email protected]>
> Signed-off-by: Greg Thelen <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>