bisecting fixing commit since 0bddd227f3dc55975e2b8dfa7fc6f959b062a2c7
building syzkaller on bc238812ae6d1f5a7e99ff60b5b3089a73f1cfb3
testing commit 0bddd227f3dc55975e2b8dfa7fc6f959b062a2c7 with gcc (GCC) 8.4.1 20210217
kernel signature: bf492e817354b874897b1bd9a996982df10917e6213b1970c606a30cf4fe6d94
run #0: crashed: general protection fault in free_netdev
run #1: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #2: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #3: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #4: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #5: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #6: crashed: general protection fault in free_netdev
run #7: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #8: crashed: general protection fault in free_netdev
run #9: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #10: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #11: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #12: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #13: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #14: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #15: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #16: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #17: crashed: KASAN: use-after-free Read in netdevice_event_work_handler
run #18: crashed: unregister_netdevice: waiting for DEV to become free
run #19: OK
testing current HEAD 1678e493d530e7977cce34e59a86bb86f3c5631e
testing commit 1678e493d530e7977cce34e59a86bb86f3c5631e with gcc (GCC) 10.2.1 20210217
kernel signature: 7c1825a04ae1b3784848cef247c5d55af45d785a4bc5b81b7ad620b32a1e56cd
run #0: crashed: unregister_netdevice: waiting for DEV to become free
run #1: crashed: unregister_netdevice: waiting for DEV to become free
run #2: crashed: unregister_netdevice: waiting for DEV to become free
run #3: crashed: unregister_netdevice: waiting for DEV to become free
run #4: crashed: unregister_netdevice: waiting for DEV to become free
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
revisions tested: 2, total time: 35m58.013263495s (build: 11m50.93098521s, test: 23m14.808615103s)
the crash still happens on HEAD
commit msg: Merge tag 'lto-v5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
crash: unregister_netdevice: waiting for DEV to become free
unregister_netdevice: waiting for sit0 to become free. Usage count = -1