2012-06-23 06:15:54

by Wanpeng Li

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

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]>
---
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


2012-06-23 08:15:41

by Johannes Weiner

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

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

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

2012-06-23 09:04:09

by Wanpeng Li

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

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 <[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.
>
>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

2012-06-23 09:27:15

by Johannes Weiner

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

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 <[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.
> >
> >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?

2012-06-25 04:26:51

by Kamezawa Hiroyuki

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

(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 <[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.
>>>
>>> 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

2012-06-25 04:46:49

by Wanpeng Li

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

On Mon, Jun 25, 2012 at 01:24:26PM +0900, Kamezawa Hiroyuki wrote:
>(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 <[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.
>>>>
>>>>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.

Thank you for your comments Kame! :-) I will do this in next version.
Is any suggestion about patches in this patchset.

Regards,
Wanpeng Li

>
>Thanks,
>-Kame
>