bisecting fixing commit since e8878ab825450c9ac07a0fc22e1f66fdb62b4f72
building syzkaller on 79fb24e23d3bc27ad2cbb1595e76860ef9743d86
testing commit e8878ab825450c9ac07a0fc22e1f66fdb62b4f72 with gcc (GCC) 8.4.1 20210217
kernel signature: eaab7609560d8fc2b2b62cd12b219036061254834125fa58e144589629f1d82d
all runs: crashed: WARNING in hci_conn_timeout
testing current HEAD dd860052c99b1e088352bdd4fb7aef46f8d2ef47
testing commit dd860052c99b1e088352bdd4fb7aef46f8d2ef47 with gcc (GCC) 10.2.1 20210217
kernel signature: 9758d9d5dc8f493a359dfa97ff39c8ce0e7204fb24c87244b12497d5a85e5acd
all runs: crashed: WARNING in hci_conn_timeout
revisions tested: 2, total time: 22m52.461106185s (build: 11m40.41300266s, test: 10m11.079574432s)
the crash still happens on HEAD
commit msg: Merge tag 'tag-chrome-platform-for-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux
crash: WARNING in hci_conn_timeout
------------[ cut here ]------------
WARNING: CPU: 0 PID: 6125 at net/bluetooth/hci_conn.c:445 queue_work include/linux/workqueue.h:507 [inline]
WARNING: CPU: 0 PID: 6125 at net/bluetooth/hci_conn.c:445 schedule_work include/linux/workqueue.h:568 [inline]
WARNING: CPU: 0 PID: 6125 at net/bluetooth/hci_conn.c:445 hci_connect_le_scan_remove net/bluetooth/hci_conn.c:195 [inline]
WARNING: CPU: 0 PID: 6125 at net/bluetooth/hci_conn.c:445 hci_conn_timeout+0x1cf/0x230 net/bluetooth/hci_conn.c:460
Modules linked in:
CPU: 0 PID: 6125 Comm: kworker/u5:1 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci1 hci_conn_timeout

RIP: 0010:hci_conn_timeout+0x1cf/0x230 net/bluetooth/hci_conn.c:445
Code: ff df 48 8d 93 a0 02 00 00 48 c1 e8 03 80 3c 08 00 75 4c 48 8b 35 99 96 b5 03 48 83 c4 08 bf 40 00 00 00 5b 5d e9 31 37 b7 fa <0f> 0b e9 85 fe ff ff 48 89 ef e8 a2 d9 16 fb e9 64 fe ff ff e8 78
RSP: 0018:ffffc90000fefd08 EFLAGS: 00010282

RAX: 00000000fffff4e0 RBX: ffff88811b1e8130 RCX: ffffffff868f195d
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88811b1e8010
RBP: ffff88811b1e8010 R08: 0000000000000000 R09: ffff88811b1e8013
R10: ffffed102363d002 R11: 0000000000000000 R12: ffffc90000fefdb0
R13: ffff888112fea400 R14: ffff88811b1e8130 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f6500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564f626fd8b0 CR3: 0000000122dff003 CR4: 00000000001706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 process_one_work+0x84c/0x13b0 kernel/workqueue.c:2275
 worker_thread+0x598/0xf80 kernel/workqueue.c:2421
 kthread+0x36f/0x450 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
irq event stamp: 75545
hardirqs last  enabled at (75587): [<ffffffff87800cc2>] asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632
hardirqs last disabled at (75592): [<ffffffff8156818e>] console_trylock_spinning kernel/printk/printk.c:1855 [inline]
hardirqs last disabled at (75592): [<ffffffff8156818e>] vprintk_emit+0x36e/0x4c0 kernel/printk/printk.c:2173
softirqs last  enabled at (75582): [<ffffffff8141b570>] invoke_softirq kernel/softirq.c:433 [inline]
softirqs last  enabled at (75582): [<ffffffff8141b570>] __irq_exit_rcu kernel/softirq.c:637 [inline]
softirqs last  enabled at (75582): [<ffffffff8141b570>] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649
softirqs last disabled at (75553): [<ffffffff8141b570>] invoke_softirq kernel/softirq.c:433 [inline]
softirqs last disabled at (75553): [<ffffffff8141b570>] __irq_exit_rcu kernel/softirq.c:637 [inline]
softirqs last disabled at (75553): [<ffffffff8141b570>] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649
---[ end trace 7b7a727efffe955d ]---