bisecting fixing commit since 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14
building syzkaller on 749688d22abef3f3cb9a0480e15c19a3f2ed8e13
testing commit 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14 with gcc (GCC) 8.4.1 20210217
kernel signature: a9943df98399f90a9454a6676e28a2828e4336e1a3d212743b8363fe590110ba
all runs: crashed: WARNING in ipvlan_unregister_nf_hook
testing current HEAD 4e68c9b0763ff55eaa69d6e519f07515f1c9037b
testing commit 4e68c9b0763ff55eaa69d6e519f07515f1c9037b with gcc (GCC) 8.4.1 20210217
kernel signature: 10661c6c6e91a7211196a27b6d177e79e2930ae986d6eff093d71dede2bf4744
all runs: crashed: unregister_netdevice: waiting for DEV to become free
revisions tested: 2, total time: 22m46.027553812s (build: 15m22.453634666s, test: 6m32.59466272s)
the crash still happens on HEAD
commit msg: Linux 4.14.239
crash: unregister_netdevice: waiting for DEV to become free
unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1