Kernel 6.6.9-200.fc39.x86_64 The following bash script demonstrates the problem (run under root): ``` #!/bin/bash set -e -u -x # Some cleanups ip netns delete myspace || : ip link del qweqwe1 || : # The bug happens only with physical interfaces, not with, say, dummy one ip link property add dev enp0s20f0u2 altname myname ip netns add myspace ip link set enp0s20f0u2 netns myspace # add dummy interface + set the same altname as in background namespace. ip link add name qweqwe1 type dummy ip link property add dev qweqwe1 altname myname # Trigger the bug. The kernel will try to return ethernet interface back to root namespace, but it can not, because of conflicting altnames. ip netns delete myspace # now `ip link` will hang forever !!!!! ``` I think, the problem is obvious. Althougn I don't know how to fix. Remove conflicting altnames for interfaces that returns from killed namespaces ? On kernel 6.3.8 (at least) was another bug, that allows dulicate altnames, and it was fixed mainline somewhere. I have another script to trigger the bug on these old kernels. I did not bisect. ```` [ 494.473906] default_device_exit_net: failed to move enp0s20f0u2 to init_net: -17 [ 494.473926] ------------[ cut here ]------------ [ 494.473927] kernel BUG at net/core/dev.c:11520! [ 494.473932] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 494.473935] CPU: 3 PID: 3852 Comm: kworker/u32:17 Not tainted 6.6.9-200.fc39.x86_64 #1 [ 494.473938] Workqueue: netns cleanup_net [ 494.473944] RIP: 0010:default_device_exit_batch+0x295/0x2a0 ``` -- Segmentation fault
