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@xxxxxxxxxxxxx>
> > ---
> >   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