netdev - [PATCH net-next] selftests: net: add a hint about MACAddressPolicy=persistent

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20251127194556.2409574-1-kuba@kernel.org>
Date: Thu, 27 Nov 2025 11:45:56 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	andrew+netdev@...n.ch,
	horms@...nel.org,
	Jakub Kicinski <kuba@...nel.org>,
	shuah@...nel.org,
	linux-kselftest@...r.kernel.org
Subject: [PATCH net-next] selftests: net: add a hint about MACAddressPolicy=persistent

New NIPA installation had been reporting a few flaky tests.
arp_ndisc_evict_nocarrier is most flaky of them all.
I suspect that the flakiness is due to udev swapping the MAC
addresses on the interfaces. Extend the message in
arp_ndisc_evict_nocarrier to hint at this potential issue.
Having the neigh get fail right after ping is rather unusual,
unless udev changes the MAC addr causing a flush in the meantime.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
CC: shuah@...nel.org
CC: linux-kselftest@...r.kernel.org
---
 tools/testing/selftests/net/arp_ndisc_evict_nocarrier.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/arp_ndisc_evict_nocarrier.sh b/tools/testing/selftests/net/arp_ndisc_evict_nocarrier.sh
index 92eb880c52f2..00758f00efbf 100755
--- a/tools/testing/selftests/net/arp_ndisc_evict_nocarrier.sh
+++ b/tools/testing/selftests/net/arp_ndisc_evict_nocarrier.sh
@@ -75,7 +75,7 @@ setup_v4() {
     ip neigh get $V4_ADDR1 dev veth0 >/dev/null 2>&1
     if [ $? -ne 0 ]; then
         cleanup_v4
-        echo "failed"
+        echo "failed; is the system using MACAddressPolicy=persistent ?"
         exit 1
     fi
 
-- 
2.51.1