bisecting fixing commit since 47ec5303d73ea344e84f46660fff693c57641386
building syzkaller on 1f122f880fe2064d038c0152fbdc763974580f15
testing commit 47ec5303d73ea344e84f46660fff693c57641386 with gcc (GCC) 8.1.0
kernel signature: a5d0355cf4b1152241105e19dd885a9ebf1ca76c4629e29c1d3059444814fb46
run #0: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #1: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #2: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #3: crashed: WARNING: ODEBUG bug in hci_conn_del
run #4: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #5: crashed: WARNING: ODEBUG bug in hci_conn_del
run #6: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #7: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #8: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #9: crashed: WARNING: ODEBUG bug in cancel_delayed_work
testing current HEAD dd9fb9bb3340c791a2be106fdc895db75f177343
testing commit dd9fb9bb3340c791a2be106fdc895db75f177343 with gcc (GCC) 8.1.0
kernel signature: 4c513d9a0f71c88fdd49a37480cc95ab2bf5f5249208b1bac88bd37defb97041
run #0: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #1: crashed: WARNING: ODEBUG bug in hci_conn_del
run #2: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #3: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #4: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #5: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #6: crashed: BUG: unable to handle kernel paging request in pfifo_fast_dequeue
run #7: crashed: WARNING: ODEBUG bug in hci_conn_del
run #8: crashed: WARNING: ODEBUG bug in cancel_delayed_work
run #9: crashed: WARNING in hci_conn_timeout
revisions tested: 2, total time: 16m49.410992956s (build: 9m28.764938218s, test: 6m52.930906684s)
the crash still happens on HEAD
commit msg: Merge tags 'auxdisplay-for-linus-v5.9-rc4', 'clang-format-for-linus-v5.9-rc4' and 'compiler-attributes-for-linus-v5.9-rc4' of git://github.com/ojeda/linux
crash: WARNING in hci_conn_timeout
------------[ cut here ]------------
WARNING: CPU: 0 PID: 8303 at net/bluetooth/hci_conn.c:412 queue_work include/linux/workqueue.h:507 [inline]
WARNING: CPU: 0 PID: 8303 at net/bluetooth/hci_conn.c:412 schedule_work include/linux/workqueue.h:568 [inline]
WARNING: CPU: 0 PID: 8303 at net/bluetooth/hci_conn.c:412 hci_connect_le_scan_remove net/bluetooth/hci_conn.c:195 [inline]
WARNING: CPU: 0 PID: 8303 at net/bluetooth/hci_conn.c:412 hci_conn_timeout+0xb9/0xc0 net/bluetooth/hci_conn.c:427
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 8303 Comm: kworker/u5:4 Not tainted 5.9.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci5 hci_conn_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xa3/0xcc lib/dump_stack.c:118
 panic+0x135/0x31a kernel/panic.c:231
 __warn.cold.13+0x20/0x25 kernel/panic.c:600
 report_bug+0xc0/0xf0 lib/bug.c:198
 handle_bug+0x35/0x90 arch/x86/kernel/traps.c:234
 exc_invalid_op+0x13/0x60 arch/x86/kernel/traps.c:254
 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536
RIP: 0010:hci_conn_timeout+0xb9/0xc0 net/bluetooth/hci_conn.c:412
Code: 7d 04 40 ff 48 8d bb e8 02 00 00 e8 71 04 40 ff 48 8d 93 a0 02 00 00 5b bf 40 00 00 00 48 8b 35 8d 21 9b 01 5d e9 37 db 56 fe <0f> 0b e9 52 ff ff ff 83 ee 03 b8 01 00 00 00 40 80 fe 01 77 0f 0f
RSP: 0018:ffffc90000effe40 EFLAGS: 00010286
RAX: 00000000ffffffff RBX: ffff888122ede780 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff842f5d40 RDI: ffff8881100ce130
RBP: ffffc90000effec8 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88810fc3e680 R11: 5514467ac207910a R12: ffff888121815c00
R13: 0000000000000000 R14: ffff8881100ce130 R15: ffff8881100ce138
 process_one_work+0x26a/0x5f0 kernel/workqueue.c:2269
 worker_thread+0x38/0x380 kernel/workqueue.c:2415
 kthread+0x148/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Kernel Offset: disabled
Rebooting in 86400 seconds..