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

[Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

(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 <liwp@linux.vnet.ibm.com>
>>
>> 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 <liwp.linux@gmail.com>
>> ---
>>   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