syzbot has found a reproducer for the following issue on: HEAD commit: ef445d1539dd Merge remote-tracking branches 'origin/arm64-.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci console output: https://syzkaller.appspot.com/x/log.txt?x=1544df69980000 kernel config: https://syzkaller.appspot.com/x/.config?x=79a49b0b9ffd6585 dashboard link: https://syzkaller.appspot.com/bug?extid=733a96463546d3026b60 compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 userspace arch: arm64 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13768021980000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=176e2c7e980000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/76e73f830dca/disk-ef445d15.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/d54cbf6f6ee2/vmlinux-ef445d15.xz kernel image: https://storage.googleapis.com/syzbot-assets/9240e4c79dfc/Image-ef445d15.gz.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+733a96463546d3026b60@xxxxxxxxxxxxxxxxxxxxxxxxx BUG: workqueue leaked atomic, lock or RCU: kworker/u9:0[52] preempt=0x00000000 lock=0->1 RCU=0->0 workfn=hci_rx_work 1 lock held by kworker/u9:0/52: #0: ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline] #0: ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline] #0: ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x610/0xc934 net/bluetooth/l2cap_core.c:6830 CPU: 1 PID: 52 Comm: kworker/u9:0 Not tainted 6.10.0-rc7-syzkaller-gef445d1539dd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Workqueue: hci0 hci_rx_work Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114 dump_stack+0x1c/0x28 lib/dump_stack.c:123 process_one_work+0xdc0/0x15b8 kernel/workqueue.c:3269 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7-syzkaller-gef445d1539dd #0 Not tainted ------------------------------------------------------ kworker/u9:0/52 is trying to acquire lock: ffff0000d385e948 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work+0x624/0x15b8 kernel/workqueue.c:3222 but task is already holding lock: ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline] ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline] ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x610/0xc934 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+0x334/0x9b8 kernel/locking/lockdep.c:5774 process_one_work+0x8a0/0x15b8 kernel/workqueue.c:3255 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 -> #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+0x3384/0x763c kernel/locking/lockdep.c:5137 lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5754 process_one_work+0x668/0x15b8 kernel/workqueue.c:3223 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 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/u9:0/52: #0: ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline] #0: ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline] #0: ffff0000d9876518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x610/0xc934 net/bluetooth/l2cap_core.c:6830 stack backtrace: CPU: 1 PID: 52 Comm: kworker/u9:0 Not tainted 6.10.0-rc7-syzkaller-gef445d1539dd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Workqueue: hci0 hci_cmd_timeout Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114 dump_stack+0x1c/0x28 lib/dump_stack.c:123 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060 check_noncircular+0x310/0x404 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+0x3384/0x763c kernel/locking/lockdep.c:5137 lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5754 process_one_work+0x668/0x15b8 kernel/workqueue.c:3223 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 Bluetooth: hci0: command tx timeout BUG: workqueue leaked atomic, lock or RCU: kworker/u9:0[52] preempt=0x00000000 lock=1->0 RCU=0->0 workfn=hci_cmd_timeout INFO: lockdep is turned off. CPU: 1 PID: 52 Comm: kworker/u9:0 Not tainted 6.10.0-rc7-syzkaller-gef445d1539dd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Workqueue: hci0 hci_cmd_timeout Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114 dump_stack+0x1c/0x28 lib/dump_stack.c:123 process_one_work+0xdc0/0x15b8 kernel/workqueue.c:3269 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 Bluetooth: hci0: command tx timeout Bluetooth: hci0: command tx timeout Bluetooth: hci0: command tx timeout --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.
