[PATCH 1/6] memcg: replace unsigned long by u64 to avoid overflow

[PATCH 1/6] memcg: replace unsigned long by u64 to avoid overflow

[Wanpeng Li]

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>
---
 mm/memcontrol.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

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

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Re: [PATCH 1/6] memcg: replace unsigned long by u64 to avoid overflow

[Johannes Weiner]

On Sat, Jun 23, 2012 at 02:15:34PM +0800, Wanpeng Li wrote:
> 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.

I wonder what 16 TB of memory must think running on a 32-bit kernel...
"What is this, an address space for ants?"

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Re: [PATCH 1/6] memcg: replace unsigned long by u64 to avoid overflow

[Wanpeng Li]

On Sat, Jun 23, 2012 at 10:15:14AM +0200, Johannes Weiner wrote:
>On Sat, Jun 23, 2012 at 02:15:34PM +0800, Wanpeng Li wrote:
>> 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.
>
>I wonder what 16 TB of memory must think running on a 32-bit kernel...
>"What is this, an address space for ants?"

Hi Johannes,

You mean change all u64 in memcg to unsigned long? or something I
miss....

Regards,
Wanpeng Li

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Re: [PATCH 1/6] memcg: replace unsigned long by u64 to avoid overflow

[Johannes Weiner]

On Sat, Jun 23, 2012 at 05:03:39PM +0800, Wanpeng Li wrote:
> On Sat, Jun 23, 2012 at 10:15:14AM +0200, Johannes Weiner wrote:
> >On Sat, Jun 23, 2012 at 02:15:34PM +0800, Wanpeng Li wrote:
> >> 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.
> >
> >I wonder what 16 TB of memory must think running on a 32-bit kernel...
> >"What is this, an address space for ants?"
> 
> Hi Johannes,
> 
> You mean change all u64 in memcg to unsigned long? or something I
> miss....

Not _all_ of them, we have some that count bytes.  But those counting
pages should probably be ulong, yes.

I think Kame added the ones that you wanted to adjust the surroundings
for in particular, so let's ask him.  Kame?

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Re: [PATCH 1/6] memcg: replace unsigned long by u64 to avoid overflow

[Kamezawa Hiroyuki]

(2012/06/23 18:26), Johannes Weiner wrote:
> On Sat, Jun 23, 2012 at 05:03:39PM +0800, Wanpeng Li wrote:
>> On Sat, Jun 23, 2012 at 10:15:14AM +0200, Johannes Weiner wrote:
>>> On Sat, Jun 23, 2012 at 02:15:34PM +0800, Wanpeng Li wrote:
>>>> 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.
>>>
>>> I wonder what 16 TB of memory must think running on a 32-bit kernel...
>>> "What is this, an address space for ants?"
>>
>> Hi Johannes,
>>
>> You mean change all u64 in memcg to unsigned long? or something I
>> miss....
>
> Not _all_ of them, we have some that count bytes.  But those counting
> pages should probably be ulong, yes.
>
> I think Kame added the ones that you wanted to adjust the surroundings
> for in particular, so let's ask him.  Kame?
>

I've been using 'unsigned long' for the number of pages and 'u64' for the number of
bytes. I think it's enough and it should be. I don't have any reason to use u64 for
the number of pages on 32bit archs.
If 'bytes' are handled by 'unsigned long', please fix it.

BTW, zone_page_state()::/include/linux/vmstat.h returns 'unsigned long'.
If you want to change this in memcg, please change zone's ones first.

Thanks,
-Kame

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