On 10/28/2016 03:19 AM, Will Deacon wrote:

On Tue, Oct 25, 2016 at 02:31:00PM -0700, David Daney wrote:

quoted

From: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>

On arm64 NUMA kernels we can pass "numa=off" on the command line to
disable NUMA.  A side effect of this is that kmalloc_node() calls to
non-zero nodes will crash the system with an OOPS:

[    0.000000] [<fffffc00081bba84>] __alloc_pages_nodemask+0xa4/0xe68
[    0.000000] [<fffffc00082163a8>] new_slab+0xd0/0x57c
[    0.000000] [<fffffc000821879c>] ___slab_alloc+0x2e4/0x514
[    0.000000] [<fffffc000823882c>] __slab_alloc+0x48/0x58
[    0.000000] [<fffffc00082195a0>] __kmalloc_node+0xd0/0x2e0
[    0.000000] [<fffffc00081119b8>] __irq_domain_add+0x7c/0x164
[    0.000000] [<fffffc0008b75d30>] its_probe+0x784/0x81c
[    0.000000] [<fffffc0008b75e10>] its_init+0x48/0x1b0
.
.
.

This is caused by code like this in kernel/irq/irqdomain.c

     domain = kzalloc_node(sizeof(*domain) + (sizeof(unsigned int) * size),
                   GFP_KERNEL, of_node_to_nid(of_node));

When NUMA is disabled, the concept of a node is really undefined, so
of_node_to_nid() should unconditionally return NUMA_NO_NODE.

Add __of_force_no_numa() to allow of_node_to_nid() to be forced to
return NUMA_NO_NODE.

The follow on patch will call this new function from the arm64 numa
code.

Reported-by: Gilbert Netzer <redacted>
Signed-off-by: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>
---
  drivers/of/of_numa.c | 15 +++++++++++++++
  include/linux/of.h   |  2 ++
  2 files changed, 17 insertions(+)

diff --git a/drivers/of/of_numa.c b/drivers/of/of_numa.c
index f63d4b0d..2212299 100644
--- a/drivers/of/of_numa.c
+++ b/drivers/of/of_numa.c

@@ -150,12 +150,27 @@ static int __init of_numa_parse_distance_map(void)
  	return ret;
  }

+static bool of_force_no_numa;
+
+void __of_force_no_numa(void)
+{
+	of_force_no_numa = true;
+}
+
  int of_node_to_nid(struct device_node *device)
  {
  	struct device_node *np;
  	u32 nid;
  	int r = -ENODATA;

+	/*
+	 * If NUMA forced off, nodes are meaningless.  Return
+	 * NUMA_NO_NODE so that any node specific memory allocations
+	 * can succeed from the default pool.
+	 */
+	if (of_force_no_numa)
+		return NUMA_NO_NODE;

Why don't you just check if the nid you get back from the device is set in
numa_nodes_parsed and return NUMA_NO_NODE if not?

numa_nodes_parsed is __initdata.  Perhaps node_possible_map would be better.

I will try that.

David.

Will

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