[PATCH AUTOSEL 5.4 73/74] MIPS: loongsoon64: Reserve memory below starting pfn to prevent Oops

Sasha Levin
2021-07-06T12:01:39Z

From: zhanglianjie <zhanglianjie@uniontech.com>

[ Upstream commit 6817c944430d00f71ccaa9c99ff5b0096aeb7873 ]

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>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/mips/loongson64/loongson-3/numa.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/mips/loongson64/loongson-3/numa.c b/arch/mips/loongson64/loongson-3/numa.c
index 8f20d2cb3767..7e7376cc94b1 100644
--- a/arch/mips/loongson64/loongson-3/numa.c
+++ b/arch/mips/loongson64/loongson-3/numa.c
@@ -200,6 +200,9 @@ 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);
+
+ /* Reserve pfn range 0~node[0]->node_start_pfn */
+ memblock_reserve(0, PAGE_SIZE * start_pfn);
}
}

--
2.30.2