linux-kernel - [PATCH v2] of, numa: Return NUMA_NO_NODE from disable of_node_to

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Message-Id: <1477689302-32671-1-git-send-email-ddaney.cavm@gmail.com>
Date:   Fri, 28 Oct 2016 14:15:02 -0700
From:   David Daney <ddaney.cavm@...il.com>
To:     linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>
Cc:     Robert Richter <rric@...nel.org>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        Ganapatrao Kulkarni <gkulkarni@...iumnetworks.com>,
        Gilbert Netzer <noname@....kth.se>,
        David Daney <david.daney@...ium.com>
Subject: [PATCH v2] of, numa: Return NUMA_NO_NODE from disable of_node_to_nid() if nid not possible.

From: David Daney <david.daney@...ium.com>

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] ITS@...000901000020000: allocated 2097152 Devices @10002000000 (flat, esz 8, psz 64K, shr 1)
[    0.000000] Unable to handle kernel NULL pointer dereference at virtual address 00001680
[    0.000000] pgd = fffffc0009470000
[    0.000000] [00001680] *pgd=0000010ffff90003, *pud=0000010ffff90003, *pmd=0000010ffff90003, *pte=0000000000000000
[    0.000000] Internal error: Oops: 96000006 [#1] SMP
.
.
.
[    0.000000] [<fffffc00081c8950>] __alloc_pages_nodemask+0xa4/0xe68
[    0.000000] [<fffffc000821fa70>] new_slab+0xd0/0x564
[    0.000000] [<fffffc0008221e24>] ___slab_alloc+0x2e4/0x514
[    0.000000] [<fffffc0008239498>] __slab_alloc+0x48/0x58
[    0.000000] [<fffffc0008222c20>] __kmalloc_node+0xd0/0x2dc
[    0.000000] [<fffffc0008115374>] __irq_domain_add+0x7c/0x164
[    0.000000] [<fffffc0008b461dc>] its_probe+0x784/0x81c
[    0.000000] [<fffffc0008b462bc>] its_init+0x48/0x1b0
[    0.000000] [<fffffc0008b4543c>] gic_init_bases+0x228/0x360
[    0.000000] [<fffffc0008b456bc>] gic_of_init+0x148/0x1cc
[    0.000000] [<fffffc0008b5aec8>] of_irq_init+0x184/0x298
[    0.000000] [<fffffc0008b43f9c>] irqchip_init+0x14/0x38
[    0.000000] [<fffffc0008b12d60>] init_IRQ+0xc/0x30
[    0.000000] [<fffffc0008b10a3c>] start_kernel+0x240/0x3b8
[    0.000000] [<fffffc0008b101c4>] __primary_switched+0x30/0x6c
[    0.000000] Code: 912ec2a0 b9403809 0a0902fb 37b007db (f9400300)
.
.
.

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.

Fix by returning NUMA_NO_NODE when the nid is not in the set of
possible nodes.

Reported-by: Gilbert Netzer <noname@....kth.se>
Signed-off-by: David Daney <david.daney@...ium.com>
---
 drivers/of/of_numa.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/of/of_numa.c b/drivers/of/of_numa.c
index f63d4b0d..a53982a 100644
--- a/drivers/of/of_numa.c
+++ b/drivers/of/of_numa.c
@@ -176,7 +176,12 @@ int of_node_to_nid(struct device_node *device)
 			np->name);
 	of_node_put(np);
 
-	if (!r)
+	/*
+	 * If numa=off passed on command line, or with a defective
+	 * device tree, the nid may not be in the set of possible
+	 * nodes.  Check for this case and return NUMA_NO_NODE.
+	 */
+	if (!r && nid < MAX_NUMNODES && node_possible(nid))
 		return nid;
 
 	return NUMA_NO_NODE;
-- 
1.8.3.1