linux-kernel - Re: [PATCH] mm: fix panic caused by __page_handle

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Message-ID: <4bb8b27e-2926-82db-0da2-dbead13c9b69@linux.alibaba.com>
Date:   Tue, 31 Aug 2021 17:35:00 +0800
From:   王贇 <yun.wang@...ux.alibaba.com>
To:     HORIGUCHI NAOYA(堀口 直也) 
        <naoya.horiguchi@....com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "open list:HWPOISON MEMORY FAILURE HANDLING" <linux-mm@...ck.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: fix panic caused by __page_handle_poison()



On 2021/8/31 下午5:11, HORIGUCHI NAOYA(堀口 直也) wrote:
> On Mon, Aug 30, 2021 at 06:07:56PM +0800, 王贇 wrote:
>> By commit 510d25c92ec4 ("mm/hwpoison: disable pcp for
>> page_handle_poison()"), __page_handle_poison() was
>> introduced, and if we mark:
>>
>> RET_A = dissolve_free_huge_page();
>> RET_B = take_page_off_buddy();
>>
>> then __page_handle_poison was supposed to return TRUE When
>> RET_A == 0 && RET_B == TRUE
>>
>> But since it failed to take care the case when RET_A is
>> -EBUSY or -ENOMEM, and just return the ret as a bool which
>> actually become TRUE, it break the original logical.
> 
> s/logical/logic/ ?

Will Fix it in v2.

> 
>>
>> The following result is a huge page in freelist but was
>> referenced as poisoned, and lead into the final panic:
>>
>>   kernel BUG at mm/internal.h:95!
>>   invalid opcode: 0000 [#1] SMP PTI
>>   skip...
>>   RIP: 0010:set_page_refcounted mm/internal.h:95 [inline]
>>   RIP: 0010:remove_hugetlb_page+0x23c/0x240 mm/hugetlb.c:1371
>>   skip...
>>   Call Trace:
>>    remove_pool_huge_page+0xe4/0x110 mm/hugetlb.c:1892
>>    return_unused_surplus_pages+0x8d/0x150 mm/hugetlb.c:2272
>>    hugetlb_acct_memory.part.91+0x524/0x690 mm/hugetlb.c:4017
>>
>> This patch replace 'bool' with 'int' to handle RET_A correctly.
>>
>> Reported-by: Abaci <abaci@...ux.alibaba.com>
>> Signed-off-by: Michael Wang <yun.wang@...ux.alibaba.com>
> 
> Thank you very much, this fix is totally right.
> 
> Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>
> 
> Could you add the following tags, too?
> 
> Fixes: 510d25c92ec4 ("mm/hwpoison: disable pcp for page_handle_poison()")
> Cc: <stable@...r.kernel.org> # 5.14

Thanks for the review, will add in v2 and send out soon.

Regards,
Michael Wang

> 
> Thanks,
> Naoya Horiguchi
>