** Description changed:
- Issue found with 5.6.0-1048-oem
-
- While debugging bug 1880631, I found that this test will cause dmesg flooded
with:
+ [Impact]
+ While debugging bug 1880631, I found that this l2tp.sh test from
kselftest/net will cause dmesg on Focal OEM 5.6 kernel flooded on with:
"unregister_netdevice: waiting for eth0 to become free. Usage count = 1"
for about every 10 secondes.
Test log:
$ sudo ./l2tp.sh
TEST: IPv4 basic L2TP tunnel [ OK ]
TEST: IPv4 route through L2TP tunnel [ OK ]
TEST: IPv6 basic L2TP tunnel [ OK ]
TEST: IPv6 route through L2TP tunnel [ OK ]
TEST: IPv4 basic L2TP tunnel - with IPsec [ OK ]
TEST: IPv4 route through L2TP tunnel - with IPsec [ OK ]
TEST: IPv6 basic L2TP tunnel - with IPsec [ OK ]
TEST: IPv6 route through L2TP tunnel - with IPsec [ OK ]
TEST: IPv4 basic L2TP tunnel [ OK ]
TEST: IPv4 route through L2TP tunnel [ OK ]
TEST: IPv6 basic L2TP tunnel - with IPsec [ OK ]
TEST: IPv6 route through L2TP tunnel - with IPsec [ OK ]
TEST: IPv4 basic L2TP tunnel - after IPsec teardown [ OK ]
TEST: IPv4 route through L2TP tunnel - after IPsec teardown [ OK ]
TEST: IPv6 basic L2TP tunnel - after IPsec teardown [ OK ]
TEST: IPv6 route through L2TP tunnel - after IPsec teardown [ OK ]
Tests passed: 16
Tests failed: 0
dmesg output:
$ dmesg
Message from syslogd@glameow at Mar 16 05:01:40 ...
- kernel:[ 739.608359] unregister_netdevice: waiting for eth0 to become free.
Usage count = 1
+ kernel:[ 739.608359] unregister_netdevice: waiting for eth0 to become free.
Usage count = 1
[ 708.560589] eth1: renamed from tmp
[ 708.587396] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
[ 708.587472] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 708.616950] eth2: renamed from tmp
[ 708.643341] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 708.687057] l2tp_core: L2TP core driver, V2.0
[ 708.689380] l2tp_netlink: L2TP netlink interface
[ 708.695479] l2tp_ip: L2TP IP encapsulation support (L2TPv3)
[ 708.700061] l2tp_eth: L2TP ethernet pseudowire support (L2TPv3)
[ 708.726295] l2tp_ip6: L2TP IP encapsulation support for IPv6 (L2TPv3)
[ 708.788973] Initializing XFRM netlink socket
[ 719.448364] unregister_netdevice: waiting for eth0 to become free. Usage
count = 1
[ 729.528359] unregister_netdevice: waiting for eth0 to become free. Usage
count = 1
[ 739.608359] unregister_netdevice: waiting for eth0 to become free. Usage
count = 1
+ [Fix]
+ * 27d53323664c54 ("l2tp: remove skb_dst_set() from l2tp_xmit_skb()")
+
+ We have this patch in our generic kernels F/G/H and OEM-5.10, thus for
+ now I can see just OEM-5.6 is affected. For which this patch can be
+ cherry-picked.
+
+ [Test Case]
+ This can tested with the l2tp.sh script in the kernel tree:
+ # sh ./tools/testing/selftests/net/l2tp.sh
+
+ With the patched kernel, it won't get flooded with that
+ unregister_netdevice message anymore.
+
+ Also, I have it tested with ubuntu_stress_smoke_tests as well, to make
+ sure the sctp stressor won't trigger any issue like in bug 1854968.
+
+ Test kernel can be found here:
+ https://people.canonical.com/~phlin/kernel/lp-1919277-l2tp/
+
+ [Where problems could occur]
+ This change is testable. A quick search didn't show any know issue about this
patch. And with the same fix running in generic kernel for a while I think the
regression potential is minor.
+
+
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.6.0-1048-oem 5.6.0-1048.52
ProcVersionSignature: User Name 5.6.0-1048.52-oem 5.6.19
Uname: Linux 5.6.0-1048-oem x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
Date: Tue Mar 16 05:20:45 2021
SourcePackage: linux-signed-oem-5.6
UpgradeStatus: No upgrade log present (probably fresh install)
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https://bugs.launchpad.net/bugs/1919277
Title:
l2tp.sh from net in ubuntu_kernel_selftests cause dmesg flooded with
"unregister_netdevice: waiting for eth0 to become free. Usage count =
1" on F-OEM-5.6
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