[PATCH 4/8] Use vmalloc for large cgroups pidlist allocations

[Li Zefan]

David Rientjes wrote:
> On Thu, 20 Aug 2009, Jonathan Corbet wrote:
> 
>> On Thu, 20 Aug 2009 14:14:00 -0700
>> Andrew Morton <akpm at linux-foundation.org> wrote:
>>
>>> Hang on.  Isn't this why Dave just wrote and I just rush-merged
>>> lib/flex_array.c?
>>>
>>> Was that code evaluated for this application and judged unsuitable?  If so,
>>> for what reason?
>> Should it be helpful: I wrote an overview of the flex_array API here:
>>
>> 	http://lwn.net/Articles/345273/
>>
>> I could format it up for addition to Documentation/ if people want.
>>
> 
> It's definitely helpful for this use case, flex array can store 261,632 
> pid_t's on 64 bit.
> 

flex_array surely can be used here, or implement Paul's proposal:
	http://lkml.org/lkml/2009/7/15/226

Note both solutions will probably make the output pid list unsorted.
Or maybe we can implement flex_array_sort().