Re: [PATCH 1/2] of, numa: Add function to disable of_node_to_nid().

[David Daney]

On 10/28/2016 03:19 AM, Will Deacon wrote:
> On Tue, Oct 25, 2016 at 02:31:00PM -0700, David Daney wrote:
> > From: David Daney <david.daney@xxxxxxxxxx>
> >
> > 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 <noname@xxxxxxxxxx>
> > Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> > ---
> >   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