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

[zhanglianjie]

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.

--
Regards,
Zhang Lianjie