* [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages()
@ 2010-11-09 8:54 Greg Thelen
2010-11-09 9:10 ` Johannes Weiner
2010-11-16 3:47 ` KAMEZAWA Hiroyuki
0 siblings, 2 replies; 3+ messages in thread
From: Greg Thelen @ 2010-11-09 8:54 UTC (permalink / raw)
To: Andrew Morton
Cc: Balbir Singh, KAMEZAWA Hiroyuki, Daisuke Nishimura,
Johannes Weiner, Wu Fengguang, Minchan Kim, linux-mm,
linux-kernel, Greg Thelen
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 <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Greg Thelen <gthelen@google.com>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages()
2010-11-09 8:54 [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages() Greg Thelen
@ 2010-11-09 9:10 ` Johannes Weiner
2010-11-16 3:47 ` KAMEZAWA Hiroyuki
1 sibling, 0 replies; 3+ messages in thread
From: Johannes Weiner @ 2010-11-09 9:10 UTC (permalink / raw)
To: Greg Thelen
Cc: Andrew Morton, Balbir Singh, KAMEZAWA Hiroyuki,
Daisuke Nishimura, Wu Fengguang, Minchan Kim, linux-mm,
linux-kernel
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 <nishimura@mxp.nes.nec.co.jp>
> Signed-off-by: Greg Thelen <gthelen@google.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages()
2010-11-09 8:54 [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages() Greg Thelen
2010-11-09 9:10 ` Johannes Weiner
@ 2010-11-16 3:47 ` KAMEZAWA Hiroyuki
1 sibling, 0 replies; 3+ messages in thread
From: KAMEZAWA Hiroyuki @ 2010-11-16 3:47 UTC (permalink / raw)
To: Greg Thelen
Cc: Andrew Morton, Balbir Singh, Daisuke Nishimura, Johannes Weiner,
Wu Fengguang, Minchan Kim, linux-mm, linux-kernel
On Tue, 9 Nov 2010 00:54:13 -0800
Greg Thelen <gthelen@google.com> 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 <nishimura@mxp.nes.nec.co.jp>
> Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2010-11-16 3:52 UTC | newest]
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2010-11-09 8:54 [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages() Greg Thelen
2010-11-09 9:10 ` Johannes Weiner
2010-11-16 3:47 ` KAMEZAWA Hiroyuki
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