[PATCH 1/2] arm64/numa: fix pcpu_cpu_distance() to get correct CPU proximity
Hanjun Guo
guohanjun at huawei.com
Wed Oct 19 20:52:55 PDT 2016
From: Yisheng Xie <xieyisheng1 at huawei.com>
The pcpu_build_alloc_info() function group CPUs according to their
proximity, by call callback function @cpu_distance_fn from different
ARCHs.
For arm64 the callback of @cpu_distance_fn is
pcpu_cpu_distance(from, to)
-> node_distance(from, to)
The @from and @to for function node_distance() should be nid.
However, pcpu_cpu_distance() in arch/arm64/mm/numa.c just past the
cpu id for @from and @to.
For this incorrect cpu proximity get from ARCH, it may cause each CPU
in one group and make group_cnt out of bound:
setup_per_cpu_areas()
pcpu_embed_first_chunk()
pcpu_build_alloc_info()
in pcpu_build_alloc_info, since cpu_distance_fn will return
REMOTE_DISTANCE if we pass cpu ids (0,1,2...), so
cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE will wrongly be ture.
This may results in triggering the BUG_ON(unit != nr_units) later:
[ 0.000000] kernel BUG at 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 Comm: swapper Not tainted 4.9.0-rc1-00003-g14155ca-dirty #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 54000080 (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.
Fixes: 7af3a0a99252 ("arm64/numa: support HAVE_SETUP_PER_CPU_AREA")
Signed-off-by: Yisheng Xie <xieyisheng1 at huawei.com>
Signed-off-by: Hanjun Guo <hanjun.guo at linaro.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Will Deacon <will.deacon at arm.com>
Cc: Zhen Lei <thunder.leizhen at huawei.com>
---
arch/arm64/mm/numa.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index 778a985..34415fc 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -147,7 +147,10 @@ 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);
+ if (early_cpu_to_node(from) == early_cpu_to_node(to))
+ return LOCAL_DISTANCE;
+ else
+ return REMOTE_DISTANCE;
}
static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size,
--
1.7.12.4
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