{fromlist} arm64/numa: get correct CPU proximity

The pcpu_build_alloc_info() function group CPUs according to their
proximity, by call callback function @cpu_distance_fn from different
ARCHs.

For {fromlist} arm64 the callback of @cpu_distance_fn is
    pcpu_cpu_distance(from, to)
        -> node_distance(from, to)
however, the @from and @to for function node_distance() should be nid.

For this incorrect cpu proximity get from ARCH, it may cause each CPU
in one group and make group_cnt out of bound. This results in:

[    0.000000] kernel BUG at {fromlist} mm/percpu.c:1916!
[    0.000000] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Co{fromlist} mm: swapper Not tainted 4.9.0-rc1-00003-g14155ca-dirty torvalds#26
[    0.000000] Hardware name: Hisilicon Hi1616 Evaluation Board (DT)
[    0.000000] task: ffff000008d6e900 task.stack: ffff000008d60000
[    0.000000] PC is at pcpu_embed_first_chunk+0x420/0x704
[    0.000000] LR is at pcpu_embed_first_chunk+0x3bc/0x704
[    0.000000] pc : [<ffff000008c754f4>] lr : [<ffff000008c75490>] pstate: 800000c5
[    0.000000] sp : ffff000008d63eb0
[    0.000000] x29: ffff000008d63eb0 [    0.000000] x28: 0000000000000000
[    0.000000] x27: 0000000000000040 [    0.000000] x26: ffff8413fbfcef00
[    0.000000] x25: 0000000000000042 [    0.000000] x24: 0000000000000042
[    0.000000] x23: 0000000000001000 [    0.000000] x22: 0000000000000046
[    0.000000] x21: 0000000000000001 [    0.000000] x20: ffff000008cb3bc8
[    0.000000] x19: ffff8413fbfcf570 [    0.000000] x18: 0000000000000000
[    0.000000] x17: ffff000008e49ae0 [    0.000000] x16: 0000000000000003
[    0.000000] x15: 000000000000001e [    0.000000] x14: 0000000000000004
[    0.000000] x13: 0000000000000000 [    0.000000] x12: 000000000000006f
[    0.000000] x11: 00000413fbffff00 [    0.000000] x10: 0000000000000004
[    0.000000] x9 : 0000000000000000 [    0.000000] x8 : 0000000000000001
[    0.000000] x7 : ffff8413fbfcf63c [    0.000000] x6 : ffff000008d65d28
[    0.000000] x5 : ffff000008d65e50 [    0.000000] x4 : 0000000000000000
[    0.000000] x3 : ffff000008cb3cc8 [    0.000000] x2 : 0000000000000040
[    0.000000] x1 : 0000000000000040 [    0.000000] x0 : 0000000000000000
.
.
.
[    0.000000] Call trace:
[    0.000000] Exception stack(0xffff000008d63ce0 to 0xffff000008d63e10)
[    0.000000] 3ce0: ffff8413fbfcf570 0001000000000000 ffff000008d63eb0 ffff000008c754f4
[    0.000000] 3d00: ffff000008d63d50 ffff0000081af210 00000413fbfff010 0000000000001000
[    0.000000] 3d20: ffff000008d63d50 ffff0000081af220 00000413fbfff010 0000000000001000
[    0.000000] 3d40: 00000413fbfcef00 0000000000000004 ffff000008d63db0 ffff0000081af390
[    0.000000] 3d60: 00000413fbfcef00 0000000000001000 0000000000000000 0000000000001000
[    0.000000] 3d80: 0000000000000000 0000000000000040 0000000000000040 ffff000008cb3cc8
[    0.000000] 3da0: 0000000000000000 ffff000008d65e50 ffff000008d65d28 ffff8413fbfcf63c
[    0.000000] 3dc0: 0000000000000001 0000000000000000 0000000000000004 00000413fbffff00
[    0.000000] 3de0: 000000000000006f 0000000000000000 0000000000000004 000000000000001e
[    0.000000] 3e00: 0000000000000003 ffff000008e49ae0
[    0.000000] [<ffff000008c754f4>] pcpu_embed_first_chunk+0x420/0x704
[    0.000000] [<ffff000008c6658c>] setup_per_cpu_areas+0x38/0xc8
[    0.000000] [<ffff000008c608d8>] start_kernel+0x10c/0x390
[    0.000000] [<ffff000008c601d8>] __primary_switched+0x5c/0x64
[    0.000000] Code: b8018660 17ffffd7 6b16037f 5400008 (d4210000)
[    0.000000] ---[ end trace 0000000000000000 ]---
[    0.000000] Kernel panic - not syncing: Attempted to kill the idle task!

Fix by getting CPUs proximity through its node. We only care about
whether it is LOCAL_DISTANCE or not, for pcpu_build_alloc_info() only
use this to group CPUs.

Signed-off-by: Yisheng Xie <[email protected]>

Author: Yisheng Xie

arch/arm64/mm/numa.c

@@ -147,7 +147,14 @@ static int __init early_cpu_to_node(int cpu)
 
 static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
 {
-	return node_distance(from, to);
+#ifdef CONFIG_NEED_MULTIPLE_NODES
+	if (early_cpu_to_node(from) == early_cpu_to_node(to))
+		return LOCAL_DISTANCE;
+	else
+		return REMOTE_DISTANCE;
+#else
+	return LOCAL_DISTANCE;
+#endif
 }
 
 static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size,