On Wed 23-10-19 12:10:39, Bjorn Helgaas wrote: > On Wed, Oct 23, 2019 at 04:22:43PM +0800, Yunsheng Lin wrote: > > On 2019/10/23 5:04, Bjorn Helgaas wrote: > > > On Sat, Oct 19, 2019 at 02:45:43PM +0800, Yunsheng Lin wrote: > > > > I think the underlying problem you're addressing is that: > > > > > > - NUMA_NO_NODE == -1, > > > - dev_to_node(dev) may return NUMA_NO_NODE, > > > - kmalloc(dev) relies on cpumask_of_node(dev_to_node(dev)), and > > > - cpumask_of_node(NUMA_NO_NODE) makes an invalid array reference > > > > > > For example, on arm64, mips loongson, s390, and x86, > > > cpumask_of_node(node) returns "node_to_cpumask_map[node]", and -1 is > > > an invalid array index. > > > > The invalid array index of -1 is the underlying problem here when > > cpumask_of_node(dev_to_node(dev)) is called and cpumask_of_node() > > is not NUMA_NO_NODE aware yet. > > > > In the "numa: make node_to_cpumask_map() NUMA_NO_NODE aware" thread > > disscusion, it is requested that it is better to warn about the pcie > > device without a node assigned by the firmware before making the > > cpumask_of_node() NUMA_NO_NODE aware, so that the system with pci > > devices of "NUMA_NO_NODE" node can be fixed by their vendor. > > > > See: https://lore.kernel.org/lkml/20191011111539.GX2311@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > Right. We should warn if the NUMA node number would help us but DT or > the firmware didn't give us one. > > But we can do that independently of any cpumask_of_node() changes. > There's no need to do one patch before the other. Even if you make > cpumask_of_node() tolerate NUMA_NO_NODE, we'll still get the warning > because we're not actually changing any node assignments. Agreed. And this has been proposed previously I believe but my understanding was that Petr was against that. -- Michal Hocko SUSE Labs
