arm64: mm: update max_pfn after memory hotplug

stable inclusion
from stable-5.10.80
commit 8980f9d14481606d82a8643aee6f6d0d97fc0ea7
bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8980f9d14481606d82a8643aee6f6d0d97fc0ea7

--------------------------------

[ Upstream commit 8fac67ca ]

After new memory blocks have been hotplugged, max_pfn and max_low_pfn
needs updating to reflect on new PFNs being hot added to system.
Without this patch, debug-related functions that use max_pfn such as
get_max_dump_pfn() or read_page_owner() will not work with any page in
memory that is hot-added after boot.

Fixes: 4ab21506 ("arm64: Add memory hotplug support")
Signed-off-by: NSudarshan Rajagopalan <quic_sudaraja@quicinc.com>
Signed-off-by: NChris Goldsworthy <quic_cgoldswo@quicinc.com>
Acked-by: NDavid Hildenbrand <david@redhat.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Georgi Djakov <quic_c_gdjako@quicinc.com>
Tested-by: NGeorgi Djakov <quic_c_gdjako@quicinc.com>
Link: https://lore.kernel.org/r/a51a27ee7be66024b5ce626310d673f24107bcb8.1632853776.git.quic_cgoldswo@quicinc.comSigned-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/mm/mmu.c

@@ -1471,6 +1471,11 @@ int arch_add_memory(int nid, u64 start, u64 size,
 	if (ret)
 		__remove_pgd_mapping(swapper_pg_dir,
 				     __phys_to_virt(start), size);
+	else {
+		max_pfn = PFN_UP(start + size);
+		max_low_pfn = max_pfn;
+	}
+
 	return ret;
 }