Re: [RFC][PATCH 6/14] memcg: lockless page cgroup

[Balbir Singh <balbir@linux.vnet.ibm.com>]

Daisuke Nishimura wrote:
> On Tue, 9 Sep 2008 16:56:08 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>> On Tue, 9 Sep 2008 14:40:07 +0900
>> Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
>>
>>>> +	/* Double counting race condition ? */
>>>> +	VM_BUG_ON(page_get_page_cgroup(page));
>>>> +
>>>>  	page_assign_page_cgroup(page, pc);
>>>>  
>>>>  	mz = page_cgroup_zoneinfo(pc);
>>> I got this VM_BUG_ON at swapoff.
>>>
>>> Trying to shmem_unuse_inode a page which has been moved
>>> to swapcache by shmem_writepage causes this BUG, because
>>> the page has not been uncharged(with all the patches applied).
>>>
>>> I made a patch which changes shmem_unuse_inode to charge with
>>> GFP_NOWAIT first and shrink usage on failure, as shmem_getpage does.
>>>
>>> But I don't stick to my patch if you handle this case :)
>>>
>> Thank you for testing and sorry for no progress in these days.
>>
>> I'm sorry to say that I'll have to postpone this to remove
>> page->page_cgroup pointer. I need some more performance-improvement
>> effort to remove page->page_cgroup pointer without significant overhead.
>>
> No problem. I know about that :)
> 
> And, I've started reviewing the radix tree patch and trying to test it.
> 

Thanks, Daisuke!

-- 
	Balbir

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