bisecting fixing commit since 2c746135a12e3f329171ed168ca0078d468f6d85
building syzkaller on 0767f13fbd87c99aea7893eb64199b76be42cd61
testing commit 2c746135a12e3f329171ed168ca0078d468f6d85 with gcc (GCC) 8.1.0
kernel signature: d665bce649f7284818903b301ae310d14a0a821d23017bcfd306a4932cda0e0a
run #0: crashed: INFO: task hung in virtscsi_tmf
run #1: crashed: INFO: task hung in scsi_block_when_processing_errors
run #2: crashed: INFO: task hung in __ext4_find_entry
run #3: crashed: INFO: task hung in scsi_block_when_processing_errors
run #4: crashed: INFO: task hung in __ext4_find_entry
run #5: crashed: INFO: task hung in __ext4_find_entry
run #6: crashed: INFO: task hung in scsi_block_when_processing_errors
run #7: crashed: INFO: task hung in __ext4_find_entry
run #8: crashed: INFO: task hung in __ext4_find_entry
run #9: crashed: INFO: task hung in __ext4_find_entry
testing current HEAD c110fed0e606ff922d5cad8ab74ba9410ca41694
testing commit c110fed0e606ff922d5cad8ab74ba9410ca41694 with gcc (GCC) 8.1.0
kernel signature: 4a4c7b562869d343ed0e34ed1d7fc61fc772c4c71eb45506af0b42181e41dd9b
run #0: crashed: WARNING: ODEBUG bug in netdev_freemem
run #1: OK
run #2: OK
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
reproducer seems to be flaky
Reproducer flagged being flaky
revisions tested: 2, total time: 39m7.666891373s (build: 15m59.811424792s, test: 22m42.426017499s)
the crash still happens on HEAD
commit msg: Linux 4.19.168
crash: WARNING: ODEBUG bug in netdev_freemem
sd 0:0:1:0: device reset
sd 0:0:1:0: device reset
sd 0:0:1:0: device reset
------------[ cut here ]------------
ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x90 kernel/workqueue.c:4950
WARNING: CPU: 0 PID: 8458 at lib/debugobjects.c:328 debug_print_object+0x168/0x210 lib/debugobjects.c:325
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 8458 Comm: kworker/u4:5 Not tainted 4.19.168-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x17c/0x226 lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.7+0x1b/0x36 kernel/panic.c:541
 report_bug+0x1a4/0x200 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x200/0x350 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:debug_print_object+0x168/0x210 lib/debugobjects.c:325
Code: 50 88 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 92 00 00 00 48 8b 14 dd 80 14 50 88 4c 89 fe 48 c7 c7 a0 08 50 88 e8 07 2e 39 04 <0f> 0b 83 05 8b 1c 74 07 01 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffff8881dbc2f840 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000004 RSI: 0000000000000008 RDI: ffffffff8bad66e0
RBP: ffff8881dbc2f880 R08: ffffed103ec83d03 R09: ffffed103ec83d02
R10: ffffed103ec83d02 R11: ffff8881f641e817 R12: 0000000000000001
R13: ffffffff89988ca0 R14: ffffffff814d6710 R15: ffffffff88500f80
 __debug_check_no_obj_freed lib/debugobjects.c:785 [inline]
 debug_check_no_obj_freed+0x252/0x430 lib/debugobjects.c:817
 kfree+0xbd/0x220 mm/slab.c:3821
 kvfree+0x2c/0x30 mm/util.c:452
 netdev_freemem+0x47/0x60 net/core/dev.c:9093
 netdev_release+0x6c/0x90 net/core/net-sysfs.c:1695
 device_release+0x71/0x1d0 drivers/base/core.c:1061
 kobject_cleanup lib/kobject.c:662 [inline]
 kobject_release lib/kobject.c:691 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x14f/0x410 lib/kobject.c:708
 netdev_run_todo+0x459/0x690 net/core/dev.c:8998
 rtnl_unlock+0x9/0x10 net/core/rtnetlink.c:117
 default_device_exit_batch+0x2e9/0x3d0 net/core/dev.c:9783
 ops_exit_list.isra.0+0xd3/0x120 net/core/net_namespace.c:156
 cleanup_net+0x368/0x850 net/core/net_namespace.c:553
 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2155
 worker_thread+0x85/0xb60 kernel/workqueue.c:2298
 kthread+0x347/0x410 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Kernel Offset: disabled
Rebooting in 86400 seconds..