[PATCH net v3 0/6] selftests: net: fix false failures due to missing features and host interference

[PATCH net v3 0/6] selftests: net: fix false failures due to missing features and host interference

[Aleksei Oladko]

Hi,

This series addresses several issues in the networking kselftests
that cause false-positive failures depending on the host environment,
kernel configuration, or library versions.

The main focus of these changes is to isolate tests from the host
environment (using namespaces) and to ensure proper fallback or
skipping when dependencies are missing.

Summary of changes:
1. Adds a check for cls_basic module in fib_tests. Without this
   module, the test fails when attempting to add tc rules instead
   of skipping.
2. Fixes ovs-dpctl.py to return a non-zero exit code when pyroute2
   is too old. This allows pmtu.sh to correctly fall back to ovs-vsctl
   instead of assuming the configuration was successful.
3,4,5. Move reuseport test into dedicated network namespaces. This prevents
   failures caused by port conflicts with host processes or interference
   from host firewall rules.
6. Ensures io_uring is enabled via sysctl before running io_uring_zerocopy
   test, preventing failures on systems where kernel.io_uring_disabled
   is set.

Signed-off-by: Aleksei Oladko <aleksey.oladko@virtuozzo.com>

Changes in v2:
- Fixed a typo by adding the missing backslash in Makefile
- Added a Fixes: tag to the appropriate commit as requested
- Link to v1: https://lore.kernel.org/linux-kselftest/20260120230558.328423-1-aleksey.oladko@virtuozzo.com

Changes in v3:
- renamed pmtu.sh to pmtu-test.sh and used pmtu.sh as the name
  of the wrapper. 
- since the test now runs in a dedicated netns, updates the ovs
  test case to correctly move network interfaces into the target
  namespace.
- Link to v2: https://lore.kernel.org/linux-kselftest/f7t1pj9v8h7.fsf@redhat.com/T/#t

Aleksei Oladko (4):
  selftests: net: fib_tests: skip rp_filter test if cls_basic is
    unavailable
  selftests: net: make ovs-dpctl.py fail when pyroute2 is unsupported
  selftests: net: rename pmtu.sh to pmtu-test.sh
  selftests: net: io_uring_zerocopy: enable io_uring for the test

Konstantin Khorenko (2):
  selftests: net: run reuseport tests in netns to avoid port conflicts
  selftests: net: run pmtu.sh in netns to avoid host firewall
    interference

 tools/testing/selftests/net/Makefile          |   13 +-
 tools/testing/selftests/net/fib_tests.sh      |    2 +
 .../selftests/net/io_uring_zerocopy_tx.sh     |    9 +
 .../selftests/net/openvswitch/ovs-dpctl.py    |    2 +-
 tools/testing/selftests/net/pmtu-test.sh      | 2492 +++++++++++++++++
 tools/testing/selftests/net/pmtu.sh           | 2492 +----------------
 tools/testing/selftests/net/reuseport_bpf.sh  |    4 +
 .../selftests/net/reuseport_bpf_cpu.sh        |    4 +
 .../selftests/net/reuseport_bpf_numa.sh       |    4 +
 .../selftests/net/reuseport_dualstack.sh      |    4 +
 10 files changed, 2531 insertions(+), 2495 deletions(-)
 create mode 100755 tools/testing/selftests/net/pmtu-test.sh
 create mode 100755 tools/testing/selftests/net/reuseport_bpf.sh
 create mode 100755 tools/testing/selftests/net/reuseport_bpf_cpu.sh
 create mode 100755 tools/testing/selftests/net/reuseport_bpf_numa.sh
 create mode 100755 tools/testing/selftests/net/reuseport_dualstack.sh

-- 
2.43.0

[PATCH net v3 1/6] selftests: net: fib_tests: skip rp_filter test if cls_basic is unavailable

[Aleksei Oladko]

The rp_filter test in fib_tests.sh installs tc filters using the
"basic" classifier but does not verify the corresponding kernel
module (cls_basic) is available. On kernels built without
CONFIG_NET_CLS_BASIC, the tc command fails and the rp_filter test
is reported as a failure.

Add a check for the presence of the cls_basic module and skip
the rp_filter test when the classifier is not available.

Signed-off-by: Aleksei Oladko <aleksey.oladko@virtuozzo.com>
---
 tools/testing/selftests/net/fib_tests.sh | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh
index c5694cc4ddd2..fa58f9b6bed0 100755
--- a/tools/testing/selftests/net/fib_tests.sh
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -441,6 +441,8 @@ fib_rp_filter_test()
 	echo
 	echo "IPv4 rp_filter tests"
 
+	modprobe cls_basic || return $ksft_skip
+
 	setup
 
 	set -e
-- 
2.43.0

[PATCH net v3 2/6] selftests: net: make ovs-dpctl.py fail when pyroute2 is unsupported

[Aleksei Oladko]

The pmtu.sh kselftest configures OVS using ovs-dpctl.py and falls back
to ovs-vsctl only when ovs-dpctl.py fails. However, ovs-dpctl.py exits
with a success status when the installed pyroute2 package version is
lower than 0.6, even though the OVS datapath is not configured.

As a result, pmtu.sh assumes that the setup was successful and
continues running the test, which later fails due to the missing
OVS configuration.

Fix the exit code handling in ovs-dpctl.py so that pmtu.sh can detect
that the setup did not complete successfully and fall back to
ovs-vsctl.

Fixes: 962e8a01eab9 ("selftests: openvswitch: Add version check for pyroute2")
Signed-off-by: Aleksei Oladko <aleksey.oladko@virtuozzo.com>
---
 tools/testing/selftests/net/openvswitch/ovs-dpctl.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
index b521e0dea506..848f61fdcee0 100644
--- a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
+++ b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
@@ -2583,7 +2583,7 @@ def main(argv):
     prverscheck = pyroute2.__version__.split(".")
     if int(prverscheck[0]) == 0 and int(prverscheck[1]) < 6:
         print("Need to upgrade the python pyroute2 package to >= 0.6.")
-        sys.exit(0)
+        sys.exit(1)
 
     parser = argparse.ArgumentParser()
     parser.add_argument(
-- 
2.43.0

[PATCH net v3 3/6] selftests: net: run reuseport tests in netns to avoid port conflicts

[Aleksei Oladko]

From: Konstantin Khorenko <khorenko@virtuozzo.com>

Some net kselftests use fixed ports which overlap with process-exporter
service already running on the host. When such a conflict happens,
the test fail with:

  failed to bind receive socket: Address already in use

Instead of changing port numbers, run the affected tests in isolated
network namespace to avoid conflicts with running daemons.

Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
---
 tools/testing/selftests/net/Makefile               | 12 ++++++++----
 tools/testing/selftests/net/reuseport_bpf.sh       |  4 ++++
 tools/testing/selftests/net/reuseport_bpf_cpu.sh   |  4 ++++
 tools/testing/selftests/net/reuseport_bpf_numa.sh  |  4 ++++
 tools/testing/selftests/net/reuseport_dualstack.sh |  4 ++++
 5 files changed, 24 insertions(+), 4 deletions(-)
 create mode 100755 tools/testing/selftests/net/reuseport_bpf.sh
 create mode 100755 tools/testing/selftests/net/reuseport_bpf_cpu.sh
 create mode 100755 tools/testing/selftests/net/reuseport_bpf_numa.sh
 create mode 100755 tools/testing/selftests/net/reuseport_dualstack.sh

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 605c54c0e8a3..8935967ad448 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -67,6 +67,10 @@ TEST_PROGS := \
 	psock_snd.sh \
 	reuseaddr_ports_exhausted.sh \
 	reuseport_addr_any.sh \
+	reuseport_bpf.sh \
+	reuseport_bpf_cpu.sh \
+	reuseport_bpf_numa.sh \
+	reuseport_dualstack.sh \
 	route_hint.sh \
 	route_localnet.sh \
 	rps_default_mask.sh \
@@ -145,6 +149,10 @@ TEST_GEN_FILES := \
 	psock_tpacket \
 	reuseaddr_ports_exhausted \
 	reuseport_addr_any \
+	reuseport_bpf \
+	reuseport_bpf_cpu \
+	reuseport_bpf_numa \
+	reuseport_dualstack \
 	rxtimestamp \
 	sctp_hello \
 	skf_net_off \
@@ -173,10 +181,6 @@ TEST_GEN_PROGS := \
 	ipv6_fragmentation \
 	proc_net_pktgen \
 	reuseaddr_conflict \
-	reuseport_bpf \
-	reuseport_bpf_cpu \
-	reuseport_bpf_numa \
-	reuseport_dualstack \
 	sk_bind_sendto_listen \
 	sk_connect_zero_addr \
 	sk_so_peek_off \
diff --git a/tools/testing/selftests/net/reuseport_bpf.sh b/tools/testing/selftests/net/reuseport_bpf.sh
new file mode 100755
index 000000000000..75014a5462a1
--- /dev/null
+++ b/tools/testing/selftests/net/reuseport_bpf.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+./in_netns.sh ./reuseport_bpf
diff --git a/tools/testing/selftests/net/reuseport_bpf_cpu.sh b/tools/testing/selftests/net/reuseport_bpf_cpu.sh
new file mode 100755
index 000000000000..243dc5bee014
--- /dev/null
+++ b/tools/testing/selftests/net/reuseport_bpf_cpu.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+./in_netns.sh ./reuseport_bpf_cpu
diff --git a/tools/testing/selftests/net/reuseport_bpf_numa.sh b/tools/testing/selftests/net/reuseport_bpf_numa.sh
new file mode 100755
index 000000000000..eccab95a3202
--- /dev/null
+++ b/tools/testing/selftests/net/reuseport_bpf_numa.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+./in_netns.sh ./reuseport_bpf_numa
diff --git a/tools/testing/selftests/net/reuseport_dualstack.sh b/tools/testing/selftests/net/reuseport_dualstack.sh
new file mode 100755
index 000000000000..82cc8e345a83
--- /dev/null
+++ b/tools/testing/selftests/net/reuseport_dualstack.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+./in_netns.sh ./reuseport_dualstack
-- 
2.43.0

[PATCH net v3 4/6] selftests: net: rename pmtu.sh to pmtu-test.sh

[Aleksei Oladko]

Rename the pmtu.sh test script to pmtu-test.sh. No functional
changes are made, only the file name is updated.

Signed-off-by: Aleksei Oladko <aleksey.oladko@virtuozzo.com>
---
 tools/testing/selftests/net/Makefile                  | 2 +-
 tools/testing/selftests/net/{pmtu.sh => pmtu-test.sh} | 0
 2 files changed, 1 insertion(+), 1 deletion(-)
 rename tools/testing/selftests/net/{pmtu.sh => pmtu-test.sh} (100%)

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 8935967ad448..b9eeeffa5fd2 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -63,7 +63,7 @@ TEST_PROGS := \
 	netns-name.sh \
 	netns-sysctl.sh \
 	nl_netdev.py \
-	pmtu.sh \
+	pmtu-test.sh \
 	psock_snd.sh \
 	reuseaddr_ports_exhausted.sh \
 	reuseport_addr_any.sh \
diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu-test.sh
similarity index 100%
rename from tools/testing/selftests/net/pmtu.sh
rename to tools/testing/selftests/net/pmtu-test.sh
-- 
2.43.0

[PATCH net v3 5/6] selftests: net: run pmtu.sh in netns to avoid host firewall interference

[Aleksei Oladko]

From: Konstantin Khorenko <khorenko@virtuozzo.com>

The pmtu.sh kselftest sets up a multi-namespace test topology where the
host network itself is part of the test setup. Test packets originating
from the created namespace are expected to reach test interface created
in the host. When firewall rules are present on the host, this traffic
may be blocked, causing the test to fail.

Run the test in an isolated network namespace to avoid interference
from host firewall rules.

Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Signed-off-by: Aleksei Oladko <aleksey.oladko@virtuozzo.com>
---
 tools/testing/selftests/net/Makefile     | 3 ++-
 tools/testing/selftests/net/pmtu-test.sh | 4 ++--
 tools/testing/selftests/net/pmtu.sh      | 4 ++++
 3 files changed, 8 insertions(+), 3 deletions(-)
 create mode 100755 tools/testing/selftests/net/pmtu.sh

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index b9eeeffa5fd2..363cd1e2cf8e 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -63,7 +63,7 @@ TEST_PROGS := \
 	netns-name.sh \
 	netns-sysctl.sh \
 	nl_netdev.py \
-	pmtu-test.sh \
+	pmtu.sh \
 	psock_snd.sh \
 	reuseaddr_ports_exhausted.sh \
 	reuseport_addr_any.sh \
@@ -194,6 +194,7 @@ TEST_FILES := \
 	fcnal-test.sh \
 	in_netns.sh \
 	lib.sh \
+	pmtu-test.sh \
 	settings \
 # end of TEST_FILES
 
diff --git a/tools/testing/selftests/net/pmtu-test.sh b/tools/testing/selftests/net/pmtu-test.sh
index a3323c21f001..2ba6bc0252f0 100755
--- a/tools/testing/selftests/net/pmtu-test.sh
+++ b/tools/testing/selftests/net/pmtu-test.sh
@@ -976,7 +976,7 @@ setup_ovs_bridge() {
 	run_cmd ip link set ovs_br0 up
 
 	run_cmd ${ns_c} ip link add veth_C-A type veth peer name veth_A-C
-	run_cmd ${ns_c} ip link set veth_A-C netns 1
+	run_cmd ${ns_c} ip link set veth_A-C netns $$
 
 	run_cmd         ip link set veth_A-C up
 	run_cmd ${ns_c} ip link set veth_C-A up
@@ -985,7 +985,7 @@ setup_ovs_bridge() {
 	setup_ovs_add_if veth_A-C
 
 	# Move veth_A-R1 to init
-	run_cmd ${ns_a} ip link set veth_A-R1 netns 1
+	run_cmd ${ns_a} ip link set veth_A-R1 netns $$
 	run_cmd ip addr add ${prefix4}.${a_r1}.1/${veth4_mask} dev veth_A-R1
 	run_cmd ip addr add ${prefix6}:${a_r1}::1/${veth6_mask} dev veth_A-R1
 	run_cmd ip link set veth_A-R1 up
diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh
new file mode 100755
index 000000000000..1805fa44a2de
--- /dev/null
+++ b/tools/testing/selftests/net/pmtu.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+./in_netns.sh ./pmtu-test.sh "$@"
-- 
2.43.0

[PATCH net v3 6/6] selftests: net: io_uring_zerocopy: enable io_uring for the test

[Aleksei Oladko]

The io_uring_zerocopy.sh kselftest assumes that io_uring support is
enabled on the host system. When io_uring is disabled via the
kernel.io_uring_disabled sysctl, the test fails.

Explicitly enable io_uring for the test by setting
kernel.io_uring_disabled=0.

Save the original value of kernel.io_uring_disabled before changing
it and restore it in cleanup handler to ensure the system state is
restored regardless of test outcome.

Signed-off-by: Aleksei Oladko <aleksey.oladko@virtuozzo.com>
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
---
 tools/testing/selftests/net/io_uring_zerocopy_tx.sh | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/testing/selftests/net/io_uring_zerocopy_tx.sh b/tools/testing/selftests/net/io_uring_zerocopy_tx.sh
index 123439545013..8c3647de9b4c 100755
--- a/tools/testing/selftests/net/io_uring_zerocopy_tx.sh
+++ b/tools/testing/selftests/net/io_uring_zerocopy_tx.sh
@@ -77,9 +77,13 @@ esac
 
 # Start of state changes: install cleanup handler
 
+old_io_uring_disabled=0
 cleanup() {
 	ip netns del "${NS2}"
 	ip netns del "${NS1}"
+	if [ "$old_io_uring_disabled" -ne 0 ]; then
+		sysctl -w -q kernel.io_uring_disabled="$old_io_uring_disabled" 2>/dev/null || true
+	fi
 }
 
 trap cleanup EXIT
@@ -122,5 +126,10 @@ do_test() {
 	wait
 }
 
+old_io_uring_disabled=$(sysctl -n kernel.io_uring_disabled 2>/dev/null || echo "0")
+if [ "$old_io_uring_disabled" -ne 0 ]; then
+	sysctl -w -q kernel.io_uring_disabled=0
+fi
+
 do_test "${EXTRA_ARGS}"
 echo ok
-- 
2.43.0

Re: [PATCH net v3 2/6] selftests: net: make ovs-dpctl.py fail when pyroute2 is unsupported

[Aaron Conole]

Aleksei Oladko <aleksey.oladko@virtuozzo.com> writes:

> The pmtu.sh kselftest configures OVS using ovs-dpctl.py and falls back
> to ovs-vsctl only when ovs-dpctl.py fails. However, ovs-dpctl.py exits
> with a success status when the installed pyroute2 package version is
> lower than 0.6, even though the OVS datapath is not configured.
>
> As a result, pmtu.sh assumes that the setup was successful and
> continues running the test, which later fails due to the missing
> OVS configuration.
>
> Fix the exit code handling in ovs-dpctl.py so that pmtu.sh can detect
> that the setup did not complete successfully and fall back to
> ovs-vsctl.
>
> Fixes: 962e8a01eab9 ("selftests: openvswitch: Add version check for pyroute2")
> Signed-off-by: Aleksei Oladko <aleksey.oladko@virtuozzo.com>
> ---

This change looks good to me.

Reviewed-by: Aaron Conole <aconole@redhat.com>

Re: [PATCH net v3 1/6] selftests: net: fib_tests: skip rp_filter test if cls_basic is unavailable

[Jakub Kicinski]

On Fri,  6 Mar 2026 00:01:22 +0000 Aleksei Oladko wrote:
> --- a/tools/testing/selftests/net/fib_tests.sh
> +++ b/tools/testing/selftests/net/fib_tests.sh
> @@ -441,6 +441,8 @@ fib_rp_filter_test()
>  	echo
>  	echo "IPv4 rp_filter tests"
>  
> +	modprobe cls_basic || return $ksft_skip

tests expects all options in tools/testing/selftests/net/config
to be enabled, we don't intend to cater to custom builds

Re: [PATCH net v3 3/6] selftests: net: run reuseport tests in netns to avoid port conflicts

[Jakub Kicinski]

On Fri,  6 Mar 2026 00:01:24 +0000 Aleksei Oladko wrote:
> Some net kselftests use fixed ports which overlap with process-exporter
> service already running on the host. When such a conflict happens,
> the test fail with:
> 
>   failed to bind receive socket: Address already in use
> 
> Instead of changing port numbers, run the affected tests in isolated
> network namespace to avoid conflicts with running daemons.

Please change the tests accordingly instead of wrapping them all 
in a script. AFAIU it's a simple matter of adding unshare() calls?

Re: [PATCH net v3 0/6] selftests: net: fix false failures due to missing features and host interference

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri,  6 Mar 2026 00:01:21 +0000 you wrote:
> Hi,
> 
> This series addresses several issues in the networking kselftests
> that cause false-positive failures depending on the host environment,
> kernel configuration, or library versions.
> 
> The main focus of these changes is to isolate tests from the host
> environment (using namespaces) and to ensure proper fallback or
> skipping when dependencies are missing.
> 
> [...]

Here is the summary with links:
  - [net,v3,1/6] selftests: net: fib_tests: skip rp_filter test if cls_basic is unavailable
    (no matching commit)
  - [net,v3,2/6] selftests: net: make ovs-dpctl.py fail when pyroute2 is unsupported
    https://git.kernel.org/netdev/net-next/c/0bcac7b11262
  - [net,v3,3/6] selftests: net: run reuseport tests in netns to avoid port conflicts
    (no matching commit)
  - [net,v3,4/6] selftests: net: rename pmtu.sh to pmtu-test.sh
    (no matching commit)
  - [net,v3,5/6] selftests: net: run pmtu.sh in netns to avoid host firewall interference
    (no matching commit)
  - [net,v3,6/6] selftests: net: io_uring_zerocopy: enable io_uring for the test
    (no matching commit)

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
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