linux-kernel - Re: [STABLE PATCH] slub: make ->cpu

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Date:   Fri, 28 Sep 2018 16:06:45 +0800
From:   zhong jiang <zhongjiang@...wei.com>
To:     Greg KH <gregkh@...ux-foundation.org>
CC:     <iamjoonsoo.kim@....com>, <rientjes@...gle.com>, <cl@...ux.com>,
        <penberg@...nel.org>, <akpm@...ux-foundation.org>,
        <mhocko@...e.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
Subject: Re: [STABLE PATCH] slub: make ->cpu_partial unsigned int

On 2018/9/27 23:46, Greg KH wrote:
> On Thu, Sep 27, 2018 at 10:43:40PM +0800, zhong jiang wrote:
>> From: Alexey Dobriyan <adobriyan@...il.com>
>>
>>         /*
>>          * cpu_partial determined the maximum number of objects
>>          * kept in the per cpu partial lists of a processor.
>>          */
>>
>> Can't be negative.
>>
>> I hit a real issue that it will result in a large number of memory leak.
>> Because Freeing slabs are in interrupt context. So it can trigger this issue.
>> put_cpu_partial can be interrupted more than once.
>> due to a union struct of lru and pobjects in struct page, when other core handles
>> page->lru list, for eaxmple, remove_partial in freeing slab code flow, It will
>> result in pobjects being a negative value(0xdead0000). Therefore, a large number
>> of slabs will be added to per_cpu partial list.
>>
>> I had posted the issue to community before. The detailed issue description is as follows.
>>
>> Link: https://www.spinics.net/lists/kernel/msg2870979.html
>>
>> After applying the patch, The issue is fixed. So the patch is a effective bugfix.
>> It should go into stable.
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read:
>     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> for how to do this properly.
>
> </formletter>
Will resend with proper format.

Thanks,
zhong jiang