Re: [PATCH] selftests: net: reuseport_bpf_numa: consider cpuless numa node

Thanks for the review!

Add Andi

On Thu, Jul 30, 2026 at 11:37:37AM +0000, [email protected] wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> - [Medium] Missing NULL check for cpumask allocation in is_cpuless_node()
> - [Medium] Missing return value check for numa_node_to_cpus() leading to masked errors
> --
> 
> --- Patch [1]: [PATCH] selftests: net: reuseport_bpf_numa: consider cpuless numa node ---
> commit 806931cbf2ad9438843e4d30f69b4887e641f7d2
> Author: Feng Tang <[email protected]>
> 
> selftests: net: reuseport_bpf_numa: consider cpuless numa node
> 
> This patch addresses a failure in the 'reuseport_bpf_numa' selftest on
> platforms with CXL memory where one node is cpuless. It introduces an
> is_cpuless_node() check to skip memory-only NUMA nodes during the binding
> test.
> 
> > diff --git a/tools/testing/selftests/net/reuseport_bpf_numa.c b/tools/testing/selftests/net/reuseport_bpf_numa.c
> > index 8ec52fc5ef41b..197dbfc475f65 100644
> > --- a/tools/testing/selftests/net/reuseport_bpf_numa.c
> > +++ b/tools/testing/selftests/net/reuseport_bpf_numa.c
> [ ... ]
> > @@ -104,13 +104,35 @@ static void attach_bpf(int fd)
> >  	close(bpf_fd);
> >  }
> >  
> > -static void send_from_node(int node_id, int family, int proto)
> > +static inline bool is_cpuless_node(int node_id)
> > +{
> > +	struct bitmask *cpumask;
> > +	bool ret = false;
> > +
> > +	cpumask = numa_allocate_cpumask();
> > +
> > +	numa_node_to_cpus(node_id, cpumask);
> 
> [Severity: Medium]
> Will this crash if numa_allocate_cpumask() fails to allocate memory?
> 
> It looks like cpumask could be NULL here, which is passed directly to
> numa_node_to_cpus() and numa_bitmask_weight() without validation.
 
Good point. 

If the allocation fail, will return 'false' to let the code go the
original flow.


> > +	if (!numa_bitmask_weight(cpumask))
> > +		ret = true;
> 
> [Severity: Medium]
> What happens if numa_node_to_cpus() fails?
> 
> It can return a negative error value, leaving the cpumask unmodified with
> zero bits set. Because the return value is not checked,
> numa_bitmask_weight(cpumask) will evaluate to 0. Does this cause the function
> to return true and silently skip testing on nodes where an error occurs,
> rather than reporting the infrastructure issue?

From the code logic (with above change), the 'node_id' and 'cpumask' have
both been validated, and this numa_node_to_cpus() is very unlikely to fail
here upon reading libnuma source code.

Thanks,
Feng

> > +
> > +	numa_bitmask_free(cpumask);
> > +	return ret;
> > +}
> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1