bisecting fixing commit since c3038e718a19fc596f7b1baba0f83d5146dc7784
building syzkaller on 8c88c9c1c99c8cd8dabc951164c820b9c9f25114
testing commit c3038e718a19fc596f7b1baba0f83d5146dc7784 with gcc (GCC) 8.1.0
kernel signature: c9c29c0b7da191d3a0db2332930d899521f8573f
all runs: crashed: WARNING: ODEBUG bug in tcindex_destroy_work
testing current HEAD fb683b5e3f53a73e761952735736180939a313df
testing commit fb683b5e3f53a73e761952735736180939a313df with gcc (GCC) 8.1.0
kernel signature: 0d2a12dc6ce4f730b75e4c88b40e801a90a2d2d6
all runs: crashed: WARNING: ODEBUG bug in tcindex_destroy_work
revisions tested: 2, total time: 36m56.025954473s (build: 16m26.422084109s, test: 20m2.22560633s)
the crash still happens on HEAD
commit msg: Linux 4.19.88
crash: WARNING: ODEBUG bug in tcindex_destroy_work
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=256 sclass=netlink_route_socket pig=19478 comm=syz-executor.3
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=256 sclass=netlink_route_socket pig=19572 comm=syz-executor.5
------------[ cut here ]------------
ODEBUG: free active (active state 0) object type: work_struct hint: tcindex_destroy_rexts_work+0x0/0x20 net/sched/cls_tcindex.c:142
WARNING: CPU: 1 PID: 304 at lib/debugobjects.c:328 debug_print_object+0x168/0x210 lib/debugobjects.c:325
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 304 Comm: kworker/u4:3 Not tainted 4.19.88-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: tc_filter_workqueue tcindex_destroy_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x123/0x177 lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.8+0x1b/0x3e 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:1037
RIP: 0010:debug_print_object+0x168/0x210 lib/debugobjects.c:325
Code: ff 86 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 92 00 00 00 48 8b 14 dd 00 21 ff 86 4c 89 fe 48 c7 c7 40 16 ff 86 e8 2b 6f 48 fe <0f> 0b 83 05 db 8f c2 05 01 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffff8880a8c17c38 EFLAGS: 00010086
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000004 RSI: 0000000000000008 RDI: ffffffff89a7d6e0
RBP: ffff8880a8c17c78 R08: ffffed1015d63ee3 R09: ffffed1015d63ee2
R10: ffffed1015d63ee2 R11: ffff8880aeb1f717 R12: 0000000000000001
R13: ffffffff87f67a40 R14: ffffffff813e3090 R15: ffffffff86ff1d20
 __debug_check_no_obj_freed lib/debugobjects.c:785 [inline]
 debug_check_no_obj_freed+0x264/0x472 lib/debugobjects.c:817
 kfree+0xbd/0x220 mm/slab.c:3821
 tcindex_destroy_work+0x2f/0x80 net/sched/cls_tcindex.c:230
 process_one_work+0x830/0x1670 kernel/workqueue.c:2153
 worker_thread+0x85/0xb60 kernel/workqueue.c:2296
 kthread+0x324/0x3e0 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

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