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

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

[Feng Tang]

'reuseport_bpf_numa' case failed on a platform with CXL memory:

	#./reuseport_bpf_numa
	---- IPv4 UDP ----
	send node 0, receive socket 0
	./reuseport_bpf_numa: failed to pin to node: Invalid argument

The root cause is that platform has 2 numa nodes: node 0 has both
cpu and memory, while node 1 is a CXL node which only has memory,
which caused numa_run_on_node() failure.

Add check to skip cpuless numa node for the numa binding test.

Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
---
 .../selftests/net/reuseport_bpf_numa.c        | 31 +++++++++++++++++--
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/net/reuseport_bpf_numa.c b/tools/testing/selftests/net/reuseport_bpf_numa.c
index 8ec52fc5ef41..197dbfc475f6 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);
+	if (!numa_bitmask_weight(cpumask))
+		ret = true;
+
+	numa_bitmask_free(cpumask);
+	return ret;
+}
+
+/*
+ * return -1 on node_id pointing to a cpuless node (like a CXL node),
+ * return 0 on successful numa setup
+ */
+static int send_from_node(int node_id, int family, int proto)
 {
 	struct sockaddr_storage saddr, daddr;
 	struct sockaddr_in  *saddr4, *daddr4;
 	struct sockaddr_in6 *saddr6, *daddr6;
 	int fd;
 
+	if (is_cpuless_node(node_id))
+		return -1;
+
 	switch (family) {
 	case AF_INET:
 		saddr4 = (struct sockaddr_in *)&saddr;
@@ -155,6 +177,7 @@ static void send_from_node(int node_id, int family, int proto)
 		error(1, errno, "failed to send message");
 
 	close(fd);
+	return 0;
 }
 
 static
@@ -213,7 +236,8 @@ static void test(int *rcv_fd, int len, int family, int proto)
 	for (node = 0; node < len; ++node) {
 		if (!numa_bitmask_isbitset(numa_nodes_ptr, node))
 			continue;
-		send_from_node(node, family, proto);
+		if (send_from_node(node, family, proto))
+			continue;
 		receive_on_node(rcv_fd, len, epfd, node, proto);
 	}
 
@@ -221,7 +245,8 @@ static void test(int *rcv_fd, int len, int family, int proto)
 	for (node = len - 1; node >= 0; --node) {
 		if (!numa_bitmask_isbitset(numa_nodes_ptr, node))
 			continue;
-		send_from_node(node, family, proto);
+		if (send_from_node(node, family, proto))
+			continue;
 		receive_on_node(rcv_fd, len, epfd, node, proto);
 	}
 
-- 
2.39.5 (Apple Git-154)

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

[sashiko-bot]

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 <feng.tang@linux.alibaba.com>

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.

> +	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?

> +
> +	numa_bitmask_free(cpumask);
> +	return ret;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260730113040.75718-1-feng.tang@linux.alibaba.com?part=1