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

[zhanglianjie]

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@xxxxxxxxxxxxx>
> > > > ---
> > > >   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