Re: [PATCH] memcg: Free spare array to avoid memory leak

[Sha Zhengju <handai.szj-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 03/08/2012 07:08 AM, Kirill A. Shutemov wrote:
> On Tue, Mar 06, 2012 at 08:13:24PM +0800, Sha Zhengju wrote:
>> From: Sha Zhengju<handai.szj-3b8fjiQLQpfQT0dZR+AlfA@public.gmane.org>
>>
>> When the last event is unregistered, there is no need to keep the spare
>> array anymore. So free it to avoid memory leak.
> It's not a leak. It will be freed on next event register.


Yeah, I noticed that. But what if it is just the last one and no more
event registering ?


Thanks,
Sha

> Yeah, we don't have to keep spare if primary is empty. But is it worth to
> make code more complicated to save few bytes of memory?
>
>> Signed-off-by: Sha Zhengju<handai.szj-3b8fjiQLQpfQT0dZR+AlfA@public.gmane.org>
>>
>> ---
>>   mm/memcontrol.c |    6 ++++++
>>   1 files changed, 6 insertions(+), 0 deletions(-)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 22d94f5..3c09a84 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -4412,6 +4412,12 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
>>   swap_buffers:
>>   	/* Swap primary and spare array */
>>   	thresholds->spare = thresholds->primary;
>> +	/* If all events are unregistered, free the spare array */
>> +	if (!new) {
>> +		kfree(thresholds->spare);
>> +		thresholds->spare = NULL;
>> +	}
>> +
>>   	rcu_assign_pointer(thresholds->primary, new);
>>
>>   	/* To be sure that nobody uses thresholds */
>> -- 
>> 1.7.4.1
>>