On Mon, Nov 8, 2010 at 7:44 PM, Daisuke Nishimura
<nishimura@xxxxxxxxxxxxxxxxx> wrote:
> On Mon, 8 Nov 2010 17:15:20 -0800
> Greg Thelen <gthelen@xxxxxxxxxx> wrote:
>
>> Use page counts rather than byte counts to avoid overflowing
>> unsigned long local variables.
>>
>> Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
>> ---
>> mm/memcontrol.c | 10 +++++-----
>> 1 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 6c7115d..b287afd 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -1345,17 +1345,17 @@ memcg_hierarchical_free_pages(struct mem_cgroup *mem)
>> {
>> unsigned long free, min_free;
>>
> hmm, the default value of RES_LIMIT is LLONG_MAX, so I think we must declare
> "free" as unsinged long long to avoid overflow.
Agreed. I am testing a fix for that issue now. I do not want
complicate this patch with the RES_LIMIT issue you mention. The fix
will be in a separate patch.
> Thanks,
> Daisuke Nishimura.
>
>> - min_free = global_page_state(NR_FREE_PAGES) << PAGE_SHIFT;
>> + min_free = global_page_state(NR_FREE_PAGES);
>>
>> while (mem) {
>> - free = res_counter_read_u64(&mem->res, RES_LIMIT) -
>> - res_counter_read_u64(&mem->res, RES_USAGE);
>> + 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);
>> mem = parent_mem_cgroup(mem);
>> }
>>
>> - /* Translate free memory in pages */
>> - return min_free >> PAGE_SHIFT;
>> + return min_free;
>> }
>>
>> /*
>> --
>> 1.7.3.1
>>
>
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