From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f207.google.com (mail-oi1-f207.google.com [209.85.167.207]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E47531A2545 for ; Sun, 26 Jul 2026 00:38:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.207 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785026312; cv=none; b=IC4wttUBX3yXUWXvFglbW3ctvCFKYedNH7MQ5uW/uIwQoigqWldZBfyUhAFpuL3SGBbjlC8jp/3viFwXzAAedCjIepStMXmW0kxmhKEPbb5ytXErcapBtX++7QnIl8aj9mooBPk5E6WR4lqwR3T9iIVUZfOOrtuD0hvLCsZdo8A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785026312; c=relaxed/simple; bh=x2FNiL3Vx2tibEuM62MxjxOdjnH5C0ox9s0pm5tWxVs=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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2002:a05:6808:198a:b0:497:d574:6155 with SMTP id 5614622812f47-4ab6a3130e1mr4096206b6e.33.1785026308897; Sat, 25 Jul 2026 17:38:28 -0700 (PDT) Date: Sat, 25 Jul 2026 17:38:28 -0700 In-Reply-To: <6a0de9e2.050a0220.18b3cb.000d.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a655704.70955b6c.323240.0028.GAE@google.com> Subject: Re: [syzbot] [input?] possible deadlock in tasklet_action_common (2) From: syzbot To: bigeasy@linutronix.de, dmitry.torokhov@gmail.com, hdanton@sina.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, penguin-kernel@i-love.sakura.ne.jp, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: cc2b5f627e8c Add linux-next specific files for 20260714 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=13d446b9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=2290ccbf984c524f dashboard link: https://syzkaller.appspot.com/bug?extid=b5d7ab56d43de3fd5aac compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1310a232580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13c3b2ea580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/6836f8efb1da/disk-cc2b5f62.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/0109d3477cc7/vmlinux-cc2b5f62.xz kernel image: https://storage.googleapis.com/syzbot-assets/c2e49e350bbf/bzImage-cc2b5f62.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b5d7ab56d43de3fd5aac@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.50/6022 is trying to acquire lock: ffff8880b86241a8 (tasklet_sync_callback.cb_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] ffff8880b86241a8 (tasklet_sync_callback.cb_lock){+...}-{3:3}, at: tasklet_lock_callback kernel/softirq.c:881 [inline] ffff8880b86241a8 (tasklet_sync_callback.cb_lock){+...}-{3:3}, at: tasklet_action_common+0xc5/0x600 kernel/softirq.c:931 but task is already holding lock: ffff88802bcbc270 (&dev->event_lock#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] ffff88802bcbc270 (&dev->event_lock#2){+.+.}-{3:3}, at: class_spinlock_irqsave_constructor include/linux/spinlock.h:620 [inline] ffff88802bcbc270 (&dev->event_lock#2){+.+.}-{3:3}, at: input_inject_event+0xab/0x310 drivers/input/input.c:419 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&dev->event_lock#2){+.+.}-{3:3}: rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] class_spinlock_irqsave_constructor include/linux/spinlock.h:620 [inline] input_inject_event+0xab/0x310 drivers/input/input.c:419 led_trigger_event+0x13b/0x220 drivers/leds/led-triggers.c:420 kbd_propagate_led_state drivers/tty/vt/keyboard.c:1124 [inline] kbd_bh+0x1b4/0x2c0 drivers/tty/vt/keyboard.c:1303 tasklet_action_common+0x31c/0x600 kernel/softirq.c:942 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1155 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (tasklet_sync_callback.cb_lock){+...}-{3:3}: check_prev_add kernel/locking/lockdep.c:3181 [inline] check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x15ff/0x2e40 kernel/locking/lockdep.c:5254 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5906 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] tasklet_lock_callback kernel/softirq.c:881 [inline] tasklet_action_common+0xc5/0x600 kernel/softirq.c:931 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302 local_bh_enable include/linux/bottom_half.h:33 [inline] __alloc_skb+0x1ad/0x7a0 net/core/skbuff.c:699 alloc_skb include/linux/skbuff.h:1384 [inline] hidp_send_message+0xb5/0x230 net/bluetooth/hidp/core.c:108 hidp_send_intr_message net/bluetooth/hidp/core.c:140 [inline] hidp_input_event+0x2a4/0x380 net/bluetooth/hidp/core.c:172 input_event_dispose+0x80/0x6b0 drivers/input/input.c:322 input_inject_event+0x1fa/0x310 drivers/input/input.c:424 kbd_led_trigger_activate+0xbc/0x100 drivers/tty/vt/keyboard.c:1080 led_trigger_set+0x52b/0x940 drivers/leds/led-triggers.c:220 led_match_default_trigger drivers/leds/led-triggers.c:277 [inline] led_trigger_set_default+0x269/0x2a0 drivers/leds/led-triggers.c:300 led_classdev_register_ext+0x761/0x990 drivers/leds/led-class.c:596 led_classdev_register include/linux/leds.h:274 [inline] input_leds_connect+0x4de/0x750 drivers/input/input-leds.c:145 input_attach_handler drivers/input/input.c:1011 [inline] input_register_device+0xd08/0x1150 drivers/input/input.c:2398 hidp_session_dev_add net/bluetooth/hidp/core.c:871 [inline] hidp_session_probe+0x1a5/0x8b0 net/bluetooth/hidp/core.c:1149 l2cap_register_user+0xbd/0x1d0 net/bluetooth/l2cap_core.c:1754 hidp_connection_add+0x1582/0x1a10 net/bluetooth/hidp/core.c:1421 do_hidp_sock_ioctl net/bluetooth/hidp/sock.c:78 [inline] hidp_sock_ioctl+0x403/0x650 net/bluetooth/hidp/sock.c:125 sock_do_ioctl+0x101/0x320 net/socket.c:1340 sock_ioctl+0x57d/0x7f0 net/socket.c:1461 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&dev->event_lock#2); lock(tasklet_sync_callback.cb_lock); lock(&dev->event_lock#2); lock(tasklet_sync_callback.cb_lock); *** DEADLOCK *** locks held by syz.2.50/6022: 10, last CPU#0: #0: ffff88802a6afb70 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_register_user+0x34/0x1d0 net/bluetooth/l2cap_core.c:1741 #1: ffffffff8f973720 (hidp_session_sem){++++}-{4:4}, at: hidp_session_probe+0x98/0x8b0 net/bluetooth/hidp/core.c:1139 #2: ffffffff8f236758 (input_mutex){+.+.}-{4:4}, at: class_mutex_intr_constructor include/linux/mutex.h:255 [inline] #2: ffffffff8f236758 (input_mutex){+.+.}-{4:4}, at: input_register_device+0xa7f/0x1150 drivers/input/input.c:2394 #3: ffff88803c562860 (&led_cdev->led_access){+.+.}-{4:4}, at: led_classdev_register_ext+0x45e/0x990 drivers/leds/led-class.c:554 #4: ffffffff8ebefde0 (triggers_list_lock){++++}-{4:4}, at: led_trigger_set_default+0x7b/0x2a0 drivers/leds/led-triggers.c:297 #5: ffff88803c562788 (&led_cdev->trigger_lock){+.+.}-{4:4}, at: led_trigger_set_default+0x8b/0x2a0 drivers/leds/led-triggers.c:298 #6: ffff88802bcbc270 (&dev->event_lock#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #6: ffff88802bcbc270 (&dev->event_lock#2){+.+.}-{3:3}, at: class_spinlock_irqsave_constructor include/linux/spinlock.h:620 [inline] #6: ffff88802bcbc270 (&dev->event_lock#2){+.+.}-{3:3}, at: input_inject_event+0xab/0x310 drivers/input/input.c:419 #7: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #7: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #7: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #7: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 #8: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #8: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #8: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1183 [inline] #8: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: input_inject_event+0xb7/0x310 drivers/input/input.c:420 #9: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 stack backtrace: CPU: 0 UID: 0 PID: 6022 Comm: syz.2.50 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2059 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2191 check_prev_add kernel/locking/lockdep.c:3181 [inline] check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x15ff/0x2e40 kernel/locking/lockdep.c:5254 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5906 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] tasklet_lock_callback kernel/softirq.c:881 [inline] tasklet_action_common+0xc5/0x600 kernel/softirq.c:931 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302 local_bh_enable include/linux/bottom_half.h:33 [inline] __alloc_skb+0x1ad/0x7a0 net/core/skbuff.c:699 alloc_skb include/linux/skbuff.h:1384 [inline] hidp_send_message+0xb5/0x230 net/bluetooth/hidp/core.c:108 hidp_send_intr_message net/bluetooth/hidp/core.c:140 [inline] hidp_input_event+0x2a4/0x380 net/bluetooth/hidp/core.c:172 input_event_dispose+0x80/0x6b0 drivers/input/input.c:322 input_inject_event+0x1fa/0x310 drivers/input/input.c:424 kbd_led_trigger_activate+0xbc/0x100 drivers/tty/vt/keyboard.c:1080 led_trigger_set+0x52b/0x940 drivers/leds/led-triggers.c:220 led_match_default_trigger drivers/leds/led-triggers.c:277 [inline] led_trigger_set_default+0x269/0x2a0 drivers/leds/led-triggers.c:300 led_classdev_register_ext+0x761/0x990 drivers/leds/led-class.c:596 led_classdev_register include/linux/leds.h:274 [inline] input_leds_connect+0x4de/0x750 drivers/input/input-leds.c:145 input_attach_handler drivers/input/input.c:1011 [inline] input_register_device+0xd08/0x1150 drivers/input/input.c:2398 hidp_session_dev_add net/bluetooth/hidp/core.c:871 [inline] hidp_session_probe+0x1a5/0x8b0 net/bluetooth/hidp/core.c:1149 l2cap_register_user+0xbd/0x1d0 net/bluetooth/l2cap_core.c:1754 hidp_connection_add+0x1582/0x1a10 net/bluetooth/hidp/core.c:1421 do_hidp_sock_ioctl net/bluetooth/hidp/sock.c:78 [inline] hidp_sock_ioctl+0x403/0x650 net/bluetooth/hidp/sock.c:125 sock_do_ioctl+0x101/0x320 net/socket.c:1340 sock_ioctl+0x57d/0x7f0 net/socket.c:1461 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f272c33de99 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffff0d71338 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f272c5c5fa0 RCX: 00007f272c33de99 RDX: 0000200000000200 RSI: 00000000400448c8 RDI: 0000000000000004 RBP: 00007f272c3d3eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f272c5c5fac R14: 00007f272c5c5fa0 R15: 00007f272c5c5fa0 raw-gadget.1 gadget.0: ignoring, device is not running --- 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.