Re: [PATCH v3 1/6] memcg: fix error code in hugetlb_force_memcg_empty()

[KAMEZAWA Hiroyuki]

(2012/05/12 6:17), Andrew Morton wrote:

> On Fri, 11 May 2012 18:45:18 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> 
>> The conditions are handled as -EBUSY, _now_.
> 
> The changelog is poor.  I rewrote it to
> 
> : hugetlb_force_memcg_empty() incorrectly returns 0 (success) when the
> : cgroup is found to be busy.  Return -EBUSY instead.
> 
> But it still doesn't tell us the end-user-visible effects of the bug. 
> It should.
> 


Ah, sorry. How about this ?



The force_empty interface allows to make the memcg only when the cgroup
doesn't include any tasks.

	# echo 0 > /cgroup/xxxx/memory.force_empty

If cgroup isn't empty, force_empty does nothing and retruns -EBUSY in usual
memcg, memcontrol.c. But hugetlb implementation has inconsitency with
it and returns 0 and do nothing. Fix it to return -EBUSY.

Thanks,
-Kame


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