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

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