Hello, syzbot found the following issue on: HEAD commit: 22f902dfc51e Merge tag 'i2c-for-6.10-rc7' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=156bc135980000 kernel config: https://syzkaller.appspot.com/x/.config?x=de2d4dc103148cd6 dashboard link: https://syzkaller.appspot.com/bug?extid=45ac74737e866894acb0 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17243d76980000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15832bc1980000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-22f902df.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/52eba6820000/vmlinux-22f902df.xz kernel image: https://storage.googleapis.com/syzbot-assets/b9c5671dd5ff/bzImage-22f902df.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+45ac74737e866894acb0@xxxxxxxxxxxxxxxxxxxxxxxxx BUG: workqueue leaked atomic, lock or RCU: kworker/u33:2[5195] preempt=0x00000000 lock=0->1 RCU=0->0 workfn=hci_rx_work 1 lock held by kworker/u33:2/5195: #0: ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline] #0: ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline] #0: ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x14f2/0x8ea0 net/bluetooth/l2cap_core.c:6830 CPU: 3 PID: 5195 Comm: kworker/u33:2 Not tainted 6.10.0-rc6-syzkaller-00215-g22f902dfc51e #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: hci0 hci_rx_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:114 process_one_work+0x11ea/0x1b40 kernel/workqueue.c:3269 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x6c8/0xf30 kernel/workqueue.c:3409 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc6-syzkaller-00215-g22f902dfc51e #0 Not tainted ------------------------------------------------------ kworker/u33:2/5195 is trying to acquire lock: ffff88801ef0a948 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work+0x1277/0x1b40 kernel/workqueue.c:3223 but task is already holding lock: ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline] ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline] ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x14f2/0x8ea0 net/bluetooth/l2cap_core.c:6830 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&chan->lock/1){+.+.}-{3:3}: __lock_release kernel/locking/lockdep.c:5468 [inline] lock_release+0x33e/0x6c0 kernel/locking/lockdep.c:5774 process_one_work+0xa96/0x1b40 kernel/workqueue.c:3255 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x6c8/0xf30 kernel/workqueue.c:3409 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #0 ((wq_completion)hci0#2){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 lock_acquire kernel/locking/lockdep.c:5754 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 process_one_work+0x12a6/0x1b40 kernel/workqueue.c:3223 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x6c8/0xf30 kernel/workqueue.c:3409 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&chan->lock/1); lock((wq_completion)hci0#2); lock(&chan->lock/1); lock((wq_completion)hci0#2); *** DEADLOCK *** 1 lock held by kworker/u33:2/5195: #0: ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline] #0: ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline] #0: ffff88801ac26518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x14f2/0x8ea0 net/bluetooth/l2cap_core.c:6830 stack backtrace: CPU: 2 PID: 5195 Comm: kworker/u33:2 Not tainted 6.10.0-rc6-syzkaller-00215-g22f902dfc51e #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: hci0 hci_cmd_timeout Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 lock_acquire kernel/locking/lockdep.c:5754 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 process_one_work+0x12a6/0x1b40 kernel/workqueue.c:3223 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x6c8/0xf30 kernel/workqueue.c:3409 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> Bluetooth: hci0: command tx timeout BUG: workqueue leaked atomic, lock or RCU: kworker/u33:2[5195] preempt=0x00000000 lock=1->0 RCU=0->0 workfn=hci_cmd_timeout INFO: lockdep is turned off. CPU: 2 PID: 5195 Comm: kworker/u33:2 Not tainted 6.10.0-rc6-syzkaller-00215-g22f902dfc51e #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: hci0 hci_cmd_timeout Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:114 process_one_work+0x11ea/0x1b40 kernel/workqueue.c:3269 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x6c8/0xf30 kernel/workqueue.c:3409 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> Bluetooth: hci0: command tx timeout Bluetooth: hci0: command tx timeout Bluetooth: hci0: command tx timeout --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. 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