Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v2] mm: Fix the problem of mips architecture Oops
To:     Sergei Shtylyov <sergei.shtylyov@gmail.com>,
        jiaxun.yang@flygoat.com, chenhuacai@kernel.org,
        tsbogend@alpha.franken.de
Cc:     linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210628054738.10964-1-zhanglianjie@uniontech.com>
 <d49404ca-b55c-847d-968d-273ca604b1e6@gmail.com>
From:   zhanglianjie <zhanglianjie@uniontech.com>
Message-ID: <f5db8f46-ef29-da7d-eb36-eedb7be077bc@uniontech.com>
Date:   Mon, 28 Jun 2021 17:05:53 +0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.12.0
MIME-Version: 1.0
In-Reply-To: <d49404ca-b55c-847d-968d-273ca604b1e6@gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Precedence: bulk


On 2021-06-28 16:51, Sergei Shtylyov wrote:
> Hello!
> 
> On 28.06.2021 8:47, zhanglianjie wrote:
> 
>> The cause of the problem is as follows:
>> 1. when cat /sys/devices/system/memory/memory0/valid_zones,
>>     test_pages_in_a_zone() will be called.
>> 2. test_pages_in_a_zone() finds the zone according to stat_pfn = 0.
>>     The smallest pfn of the numa node in the mips architecture is 128,
>>     and the page corresponding to the previous 0~127 pfn is not
>>     initialized (page->flags is 0xFFFFFFFF)
>> 3. The nid and zonenum obtained using page_zone(pfn_to_page(0)) are out
>>     of bounds in the corresponding array,
>>     &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)],
>>     access to the out-of-bounds zone member variables appear abnormal,
>>     resulting in Oops.
>> Therefore, it is necessary to keep the page between 0 and the minimum
>> pfn to prevent Oops from appearing.
>>
>> Signed-off-by: zhanglianjie <zhanglianjie@uniontech.com>
>> ---
>>   arch/mips/loongson64/numa.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/mips/loongson64/numa.c b/arch/mips/loongson64/numa.c
>> index fa9b4a487a47..dba9e6f17b9e 100644
>> --- a/arch/mips/loongson64/numa.c
>> +++ b/arch/mips/loongson64/numa.c
>> @@ -129,6 +129,9 @@ static void __init node_mem_init(unsigned int node)
>>           if (node_end_pfn(0) >= (0xffffffff >> PAGE_SHIFT))
>>               memblock_reserve((node_addrspace_offset | 0xfe000000),
>>                        32 << 20);
>> +
>> +        /* Reserver pfn range 0~node[0]->node_start_pfn */
> 
>     Reserve?
> 
>> +        memblock_reserve(0, PAGE_SIZE * start_pfn);
>>       }
>>   }
> [...]
> 
> MBR, Sergei
> 
> 

Oh, I’m so sorry. I will resubmit, thanks for your reminder.

-- 
Regards,
Zhang Lianjie