2012-06-25 06:04:42

by Wanpeng Li

Subject: [PATCH 1/5 v2] memcg: replace unsigned long by u64 to avoid overflow

Changlog:

V2 -> V1:
* fix zone_page_state()::/include/linux/vmstat.h returns 'unsigned long'

From: Wanpeng Li <[email protected]>

Since the return value variable in mem_cgroup_zone_nr_lru_pages and
mem_cgroup_node_nr_lru_pages functions are u64, so replace the return
value of funtions by u64 to avoid overflow.

Signed-off-by: Wanpeng Li <[email protected]>
---
include/linux/vmstat.h | 2 +-
mm/memcontrol.c | 5 ++---
2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 65efb92..6a14291 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -106,7 +106,7 @@ static inline unsigned long global_page_state(enum zone_stat_item item)
return x;
}

-static inline unsigned long zone_page_state(struct zone *zone,
+static inline u64 zone_page_state(struct zone *zone,
enum zone_stat_item item)
{
long x = atomic_long_read(&zone->vm_stat[item]);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a2677e0..724bd02 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -776,8 +776,7 @@ mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid,
return ret;
}

-static unsigned long
-mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
+static u64 mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
int nid, unsigned int lru_mask)
{
u64 total = 0;
@@ -790,7 +789,7 @@ mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
return total;
}

-static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
+static u64 mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
unsigned int lru_mask)
{
int nid;
--
1.7.9.5

2012-06-25 07:52:34

by Johannes Weiner

Subject: Re: [PATCH 1/5 v2] memcg: replace unsigned long by u64 to avoid overflow

On Mon, Jun 25, 2012 at 02:04:20PM +0800, Wanpeng Li wrote:
> Changlog:
>
> V2 -> V1:
> * fix zone_page_state()::/include/linux/vmstat.h returns 'unsigned long'
>
> From: Wanpeng Li <[email protected]>
>
> Since the return value variable in mem_cgroup_zone_nr_lru_pages and
> mem_cgroup_node_nr_lru_pages functions are u64, so replace the return
> value of funtions by u64 to avoid overflow.
>
> Signed-off-by: Wanpeng Li <[email protected]>
> ---
> include/linux/vmstat.h | 2 +-
> mm/memcontrol.c | 5 ++---
> 2 files changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
> index 65efb92..6a14291 100644
> --- a/include/linux/vmstat.h
> +++ b/include/linux/vmstat.h
> @@ -106,7 +106,7 @@ static inline unsigned long global_page_state(enum zone_stat_item item)
> return x;
> }
>
> -static inline unsigned long zone_page_state(struct zone *zone,
> +static inline u64 zone_page_state(struct zone *zone,
> enum zone_stat_item item)
> {
> long x = atomic_long_read(&zone->vm_stat[item]);

We established that there is no known reason to use ulong for page
counters and that IF YOU HAD ONE, you should obviously say so and then
do a wholesale conversion. But I don't think you have one.

This patch makes absolutely no sense.

2012-06-25 08:32:34

by Kamezawa Hiroyuki

Subject: Re: [PATCH 1/5 v2] memcg: replace unsigned long by u64 to avoid overflow

(2012/06/25 16:52), Johannes Weiner wrote:
> On Mon, Jun 25, 2012 at 02:04:20PM +0800, Wanpeng Li wrote:
>> Changlog:
>>
>> V2 -> V1:
>> * fix zone_page_state()::/include/linux/vmstat.h returns 'unsigned long'
>>
>> From: Wanpeng Li <[email protected]>
>>
>> Since the return value variable in mem_cgroup_zone_nr_lru_pages and
>> mem_cgroup_node_nr_lru_pages functions are u64, so replace the return
>> value of funtions by u64 to avoid overflow.
>>
>> Signed-off-by: Wanpeng Li <[email protected]>
>> ---
>> include/linux/vmstat.h | 2 +-
>> mm/memcontrol.c | 5 ++---
>> 2 files changed, 3 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
>> index 65efb92..6a14291 100644
>> --- a/include/linux/vmstat.h
>> +++ b/include/linux/vmstat.h
>> @@ -106,7 +106,7 @@ static inline unsigned long global_page_state(enum zone_stat_item item)
>> return x;
>> }
>>
>> -static inline unsigned long zone_page_state(struct zone *zone,
>> +static inline u64 zone_page_state(struct zone *zone,
>> enum zone_stat_item item)
>> {
>> long x = atomic_long_read(&zone->vm_stat[item]);
>
> We established that there is no known reason to use ulong for page
> counters and that IF YOU HAD ONE, you should obviously say so and then
> do a wholesale conversion. But I don't think you have one.
>
> This patch makes absolutely no sense.
>
I agree. Then, Nack from me.

Thanks,
-Kame