[PATCH v2] mm: Fix the problem of mips architecture Oops

[PATCH v2] mm: Fix the problem of mips architecture Oops

[zhanglianjie]

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 */
+		memblock_reserve(0, PAGE_SIZE * start_pfn);
 	}
 }

--
2.20.1

Re: [PATCH v2] mm: Fix the problem of mips architecture Oops

[Sergei Shtylyov]

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

Re: [PATCH v2] mm: Fix the problem of mips architecture Oops

[zhanglianjie]

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