Hello, syzbot found the following issue on: HEAD commit: bb7a2467e6be Add linux-next specific files for 20240426 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=13daed0f180000 kernel config: https://syzkaller.appspot.com/x/.config?x=5c6a0288262dd108 dashboard link: https://syzkaller.appspot.com/bug?extid=ab10eccaaf6fdf23dd55 compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/5175af7dda64/disk-bb7a2467.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/70db0462e868/vmlinux-bb7a2467.xz kernel image: https://storage.googleapis.com/syzbot-assets/3217fb825698/bzImage-bb7a2467.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+ab10eccaaf6fdf23dd55@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.9.0-rc5-next-20240426-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/6085 is trying to acquire lock: ffff8880696fc8d0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline] ffff8880696fc8d0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] ffff8880696fc8d0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4113 [inline] ffff8880696fc8d0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: __flush_work+0xe6/0xd00 kernel/workqueue.c:4172 but task is already holding lock: ffff8880696fd060 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:559 [inline] ffff8880696fd060 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x1d3/0x4e0 net/bluetooth/hci_core.c:2778 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&hdev->req_lock){+.+.}-{3:3}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 hci_cmd_sync_work+0x1ec/0x400 net/bluetooth/hci_sync.c:309 process_one_work kernel/workqueue.c:3222 [inline] process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3303 worker_thread+0x86d/0xd70 kernel/workqueue.c:3384 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 touch_work_lockdep_map kernel/workqueue.c:3885 [inline] start_flush_work kernel/workqueue.c:4139 [inline] __flush_work+0x73c/0xd00 kernel/workqueue.c:4172 __cancel_work_sync+0xbc/0x110 kernel/workqueue.c:4322 hci_cmd_sync_clear+0x30/0x220 net/bluetooth/hci_sync.c:588 hci_dev_close_sync+0xbae/0x1060 net/bluetooth/hci_sync.c:5188 hci_dev_do_close net/bluetooth/hci_core.c:561 [inline] hci_unregister_dev+0x1db/0x4e0 net/bluetooth/hci_core.c:2778 vhci_release+0x83/0xd0 drivers/bluetooth/hci_vhci.c:674 __fput+0x406/0x8b0 fs/file_table.c:422 task_work_run+0x24f/0x310 kernel/task_work.c:180 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xa27/0x27e0 kernel/exit.c:874 do_group_exit+0x207/0x2c0 kernel/exit.c:1023 __do_sys_exit_group kernel/exit.c:1034 [inline] __se_sys_exit_group kernel/exit.c:1032 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1032 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&hdev->req_lock); lock((work_completion)(&hdev->cmd_sync_work)); lock(&hdev->req_lock); lock((work_completion)(&hdev->cmd_sync_work)); *** DEADLOCK *** 2 locks held by syz-executor.0/6085: #0: ffff8880696fd060 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:559 [inline] #0: ffff8880696fd060 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x1d3/0x4e0 net/bluetooth/hci_core.c:2778 #1: ffffffff8e333ba0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline] #1: ffffffff8e333ba0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #1: ffffffff8e333ba0 (rcu_read_lock){....}-{1:2}, at: start_flush_work kernel/workqueue.c:4113 [inline] #1: ffffffff8e333ba0 (rcu_read_lock){....}-{1:2}, at: __flush_work+0xe6/0xd00 kernel/workqueue.c:4172 stack backtrace: CPU: 0 PID: 6085 Comm: syz-executor.0 Not tainted 6.9.0-rc5-next-20240426-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 check_noncircular+0x36a/0x4a0 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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 touch_work_lockdep_map kernel/workqueue.c:3885 [inline] start_flush_work kernel/workqueue.c:4139 [inline] __flush_work+0x73c/0xd00 kernel/workqueue.c:4172 __cancel_work_sync+0xbc/0x110 kernel/workqueue.c:4322 hci_cmd_sync_clear+0x30/0x220 net/bluetooth/hci_sync.c:588 hci_dev_close_sync+0xbae/0x1060 net/bluetooth/hci_sync.c:5188 hci_dev_do_close net/bluetooth/hci_core.c:561 [inline] hci_unregister_dev+0x1db/0x4e0 net/bluetooth/hci_core.c:2778 vhci_release+0x83/0xd0 drivers/bluetooth/hci_vhci.c:674 __fput+0x406/0x8b0 fs/file_table.c:422 task_work_run+0x24f/0x310 kernel/task_work.c:180 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xa27/0x27e0 kernel/exit.c:874 do_group_exit+0x207/0x2c0 kernel/exit.c:1023 __do_sys_exit_group kernel/exit.c:1034 [inline] __se_sys_exit_group kernel/exit.c:1032 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1032 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1eb1a7dea9 Code: Unable to access opcode bytes at 0x7f1eb1a7de7f. RSP: 002b:00007ffdd8d72208 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f1eb1ac93de RCX: 00007f1eb1a7dea9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000002 R08: 00007ffdd8d6ffa7 R09: 00007ffdd8d734c0 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdd8d734c0 R13: 00007f1eb1ac93b9 R14: 000000000001e31b R15: 0000000000000003 </TASK> --- 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. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. 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