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

[zhanglianjie <zhanglianjie@uniontech.com>]

On 2021-06-28 09:17, Jiaxun Yang wrote:
> 
> 在 2021/6/28 上午9:07, zhanglianjie 写道:
>>
>>
>> On 2021-06-25 21:39, Thomas Bogendoerfer wrote:
>>> On Thu, Jun 24, 2021 at 11:22:12AM +0800, 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/kernel/setup.c | 2 ++
>>>>   1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
>>>> index 23a140327a0b..f1da2b2ba5e9 100644
>>>> --- a/arch/mips/kernel/setup.c
>>>> +++ b/arch/mips/kernel/setup.c
>>>> @@ -653,6 +653,8 @@ static void __init arch_mem_init(char **cmdline_p)
>>>>        */
>>>>       memblock_set_current_limit(PFN_PHYS(max_low_pfn));
>>>>
>>>> +    memblock_reserve(0, PAGE_SIZE * NODE_DATA(0)->node_start_pfn);
>>>> +
>>>
>>> which platform needs this ? This look it should be better fixed in
>>> the platform memory registration code.
>>>
>>> Thomas.
>>>
>>
>> I have a problem on the loogson platform.
> 
> I had checked a Loongson 3A4000 board (Lemote-A1901) with UEFI firmware 
> and the region is reserved by firmware.
> 
> Hmm, you'd better contact vendor to fix the firmware. If it's not 
> possible then workaround it in arch/mips/loongson64/numa.c
> 
> Thanks.
> 
> - Jiaxun
> 
> 
> 
> 

I will try to contact the manufacturer. However, the manufacturer cannot 
be contacted temporarily. I resubmitted a patch according to your method.
thank you very much for your help.

I want to ask, how do you check that the region is reserved by UEFI 
firmware?

The machine information I tested is as follows:
1. Lemote board
- hardware information:
         Loongson 3A4000 board LEMOTE-LS3A4000-7A1000-1w-V01-pc.
- pagesize is 16k.
2. THTF board
- hardware information:
         Loongson 3A4000 board THTF-LS3A4000-7A1000-1W-VB1-ML4A
- pagesize is 16k.



-- 
Regards,
Zhang Lianjie