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Subject: Re: [RFC]mm/zsmalloc,: trigger BUG_ON in function zs_map_object.
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Minchan Kim <minchan@kernel.org>
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From: Yisheng Xie <xieyisheng1@huawei.com>
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Date: Wed, 29 Mar 2017 15:53:21 +0800
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Hi Sergey,

Thanks for your comment!
On 2017/3/29 14:42, Sergey Senozhatsky wrote:
> On (03/29/17 09:20), Minchan Kim wrote:
>> Hello,
>>
>> On Tue, Mar 28, 2017 at 03:20:22PM +0800, Yisheng Xie wrote:
>>> Hi, all,
>>>
>>> We had backport the no-lru migration to linux-4.1, meanwhile change the
>>> ZS_MAX_ZSPAGE_ORDER to 3. Then we met a BUG_ON(!page[1]).
>>
>> Hmm, I don't know how you backported.
>>
>> There isn't any problem with default ZS_MAX_ZSPAGE_ORDER. Right?
>> So, it happens only if you changed it to 3?
> 
> I agree with Minchan. too much things could have gone wrong during the backport.
> 
>> Could you tell me what is your base kernel? and what zram/zsmalloc
>> version(ie, from what kernel version) you backported to your
>> base kernel?
> 
> agree again.
> 
> 
> 
> Yisheng, do you have this commit applied?
No, we missed this patch, I will try it. Really thanks for that.

Thanks
Yisheng Xie

> 
> commit c102f07ca0b04f2cb49cfc161c83f6239d17f491
> Author: Junil Lee <junil0814.lee@lge.com>
> Date:   Wed Jan 20 14:58:18 2016 -0800
> 
>     zsmalloc: fix migrate_zspage-zs_free race condition
> 
> 
> 	-ss
> 
> .
>