Re: [PATCH] arm64, numa: Add cpu_to_node() implementation.
From: Hanjun Guo
Date: Tue Sep 20 2016 - 06:05:44 EST
On 09/20/2016 02:49 AM, David Daney wrote:
From: David Daney <david.daney@xxxxxxxxxx>
The wq_numa_init() function makes a private CPU to node map by calling
cpu_to_node() early in the boot process, before the non-boot CPUs are
brought online. Since the default implementation of cpu_to_node()
returns zero for CPUs that have never been brought online, the
workqueue system's view is that *all* CPUs are on node zero.
When the unbound workqueue for a non-zero node is created, the
tsk_cpus_allowed() for the worker threads is the empty set because
there are, in the view of the workqueue system, no CPUs on non-zero
nodes. The code in try_to_wake_up() using this empty cpumask ends up
using the cpumask empty set value of NR_CPUS as an index into the
per-CPU area pointer array, and gets garbage as it is one past the end
of the array. This results in:
[ 0.881970] Unable to handle kernel paging request at virtual address fffffb1008b926a4
[ 1.970095] pgd = fffffc00094b0000
[ 1.973530] [fffffb1008b926a4] *pgd=0000000000000000, *pud=0000000000000000, *pmd=0000000000000000
[ 1.982610] Internal error: Oops: 96000004 [#1] SMP
[ 1.987541] Modules linked in:
[ 1.990631] CPU: 48 PID: 295 Comm: cpuhp/48 Tainted: G W 4.8.0-rc6-preempt-vol+ #9
[ 1.999435] Hardware name: Cavium ThunderX CN88XX board (DT)
[ 2.005159] task: fffffe0fe89cc300 task.stack: fffffe0fe8b8c000
[ 2.011158] PC is at try_to_wake_up+0x194/0x34c
[ 2.015737] LR is at try_to_wake_up+0x150/0x34c
[ 2.020318] pc : [<fffffc00080e7468>] lr : [<fffffc00080e7424>] pstate: 600000c5
[ 2.027803] sp : fffffe0fe8b8fb10
[ 2.031149] x29: fffffe0fe8b8fb10 x28: 0000000000000000
[ 2.036522] x27: fffffc0008c63bc8 x26: 0000000000001000
[ 2.041896] x25: fffffc0008c63c80 x24: fffffc0008bfb200
[ 2.047270] x23: 00000000000000c0 x22: 0000000000000004
[ 2.052642] x21: fffffe0fe89d25bc x20: 0000000000001000
[ 2.058014] x19: fffffe0fe89d1d00 x18: 0000000000000000
[ 2.063386] x17: 0000000000000000 x16: 0000000000000000
[ 2.068760] x15: 0000000000000018 x14: 0000000000000000
[ 2.074133] x13: 0000000000000000 x12: 0000000000000000
[ 2.079505] x11: 0000000000000000 x10: 0000000000000000
[ 2.084879] x9 : 0000000000000000 x8 : 0000000000000000
[ 2.090251] x7 : 0000000000000040 x6 : 0000000000000000
[ 2.095621] x5 : ffffffffffffffff x4 : 0000000000000000
[ 2.100991] x3 : 0000000000000000 x2 : 0000000000000000
[ 2.106364] x1 : fffffc0008be4c24 x0 : ffffff0ffffada80
[ 2.111737]
[ 2.113236] Process cpuhp/48 (pid: 295, stack limit = 0xfffffe0fe8b8c020)
[ 2.120102] Stack: (0xfffffe0fe8b8fb10 to 0xfffffe0fe8b90000)
[ 2.125914] fb00: fffffe0fe8b8fb80 fffffc00080e7648
.
.
.
[ 2.442859] Call trace:
[ 2.445327] Exception stack(0xfffffe0fe8b8f940 to 0xfffffe0fe8b8fa70)
[ 2.451843] f940: fffffe0fe89d1d00 0000040000000000 fffffe0fe8b8fb10 fffffc00080e7468
[ 2.459767] f960: fffffe0fe8b8f980 fffffc00080e4958 ffffff0ff91ab200 fffffc00080e4b64
[ 2.467690] f980: fffffe0fe8b8f9d0 fffffc00080e515c fffffe0fe8b8fa80 0000000000000000
[ 2.475614] f9a0: fffffe0fe8b8f9d0 fffffc00080e58e4 fffffe0fe8b8fa80 0000000000000000
[ 2.483540] f9c0: fffffe0fe8d10000 0000000000000040 fffffe0fe8b8fa50 fffffc00080e5ac4
[ 2.491465] f9e0: ffffff0ffffada80 fffffc0008be4c24 0000000000000000 0000000000000000
[ 2.499387] fa00: 0000000000000000 ffffffffffffffff 0000000000000000 0000000000000040
[ 2.507309] fa20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
[ 2.515233] fa40: 0000000000000000 0000000000000000 0000000000000000 0000000000000018
[ 2.523156] fa60: 0000000000000000 0000000000000000
[ 2.528089] [<fffffc00080e7468>] try_to_wake_up+0x194/0x34c
[ 2.533723] [<fffffc00080e7648>] wake_up_process+0x28/0x34
[ 2.539275] [<fffffc00080d3764>] create_worker+0x110/0x19c
[ 2.544824] [<fffffc00080d69dc>] alloc_unbound_pwq+0x3cc/0x4b0
[ 2.550724] [<fffffc00080d6bcc>] wq_update_unbound_numa+0x10c/0x1e4
[ 2.557066] [<fffffc00080d7d78>] workqueue_online_cpu+0x220/0x28c
[ 2.563234] [<fffffc00080bd288>] cpuhp_invoke_callback+0x6c/0x168
[ 2.569398] [<fffffc00080bdf74>] cpuhp_up_callbacks+0x44/0xe4
[ 2.575210] [<fffffc00080be194>] cpuhp_thread_fun+0x13c/0x148
[ 2.581027] [<fffffc00080dfbac>] smpboot_thread_fn+0x19c/0x1a8
[ 2.586929] [<fffffc00080dbd64>] kthread+0xdc/0xf0
[ 2.591776] [<fffffc0008083380>] ret_from_fork+0x10/0x50
[ 2.597147] Code: b00057e1 91304021 91005021 b8626822 (b8606821)
[ 2.603464] ---[ end trace 58c0cd36b88802bc ]---
[ 2.608138] Kernel panic - not syncing: Fatal exception
Fix by supplying a cpu_to_node() implementation that returns correct
node mappings.
Cc: <stable@xxxxxxxxxxxxxxx> # 4.7.x-
Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
---
arch/arm64/include/asm/topology.h | 3 +++
arch/arm64/mm/numa.c | 18 ++++++++++++++++++
2 files changed, 21 insertions(+)
diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
index 8b57339..8d935447 100644
--- a/arch/arm64/include/asm/topology.h
+++ b/arch/arm64/include/asm/topology.h
@@ -30,6 +30,9 @@ int pcibus_to_node(struct pci_bus *bus);
cpu_all_mask : \
cpumask_of_node(pcibus_to_node(bus)))
+int cpu_to_node(int cpu);
+#define cpu_to_node cpu_to_node
+
#endif /* CONFIG_NUMA */
#include <asm-generic/topology.h>
diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index 5bb15ea..e76281b 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -130,6 +130,24 @@ void __init early_map_cpu_to_node(unsigned int cpu, int nid)
cpu_to_node_map[cpu] = nid;
}
+int cpu_to_node(int cpu)
+{
+ int nid;
+
+ /*
+ * Return 0 for unknown mapping so that we report something
+ * sensible if firmware doesn't supply a proper mapping.
+ */
+ if (cpu < 0 || cpu >= NR_CPUS)
+ return 0;
+
+ nid = cpu_to_node_map[cpu];
+ if (nid == NUMA_NO_NODE)
+ nid = 0;
+ return nid;
+}
+EXPORT_SYMBOL(cpu_to_node);
+
/**
* numa_add_memblk - Set node id to memblk
* @nid: NUMA node ID of the new memblk
Reviewed-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Thanks for the fix!
Hanjun