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 88914EEC0 for ; Thu, 30 Jul 2026 01:59:26 +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=1785376768; cv=none; b=NCfNZrkCxcNBbEOsXfh//ihVTCI5EC8KPgAYPLrGxeoMFaLDS1g63pD9x/9yuf6Ritry4XEPa8SMuE/VEpa1KD3w4EsS3agIWZuAEYz4vrw99NHREswF1cK5evrce/hGNkKxNsG4oqMLzY2dkg915CXj9/FyKGjkTIJ3Kp+I0aI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785376768; c=relaxed/simple; bh=I3wFUoQXOKceQfTuokGJdaqo6XZR30zAAggw8oiZkcY=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=p/uL7IvcEEWn9HgjnSoZYQ33VNMlw9dVZ5PEBRmGIWex9RP5NCfbaMBn0dQehLP8jih+7hfDYa64ZSFt5A8zJtmZm6FX6IRqVEsLz9JoRdt1vRxcvZL1MaZ+ku5kdCm5ThAisvHvSdRMWV2Jd1FqDgRslk9z+9Od+AG0Mk/aGNM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.167.207 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oi1-f207.google.com with SMTP id 5614622812f47-4ab8b646492so2002419b6e.0 for ; Wed, 29 Jul 2026 18:59:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785376765; x=1785981565; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=7u3xdayCRJynv9VqPZio6IuoyTlELBUlNGEE5CXoAmk=; b=AWe/hlyckuWf/cUqvhSAhS/XMNr74FjFlcUO0NgSTOxOSH8t2pMUrCODTQtC+Q1D7v MmYDhViE1Bte0HtSehV+L4ANdYfpCuZIT7zJcsTc4NsPE4bdmYYpRIcF8MrtTYbsTMdo WnycLoou2ZgRZE56nPZhk7dlhVl6xdvCVv+v+jYUIDcK4dOLprVI5/Hd6TSQ7uZDyynn hNGEiURKU2Gog+x7nCQrhSrgIyQLKodaHrBCgSrD2cE4Y1Ggr4Z6I533Ot2KSSmbGa/l mUGEiDPLQWLhbcLcHCdOrz3xn2ONrAHQ6ifGJlGmt8zeoZMVBQKJA19SH5/EtDDRBz6M zC0A== X-Gm-Message-State: AOJu0Yx8PwHz2vys8/NJrY6I91gTn0hD8opJ1KkFjf/4L4vv16AqQ6e3 REl4wc+CaCg7Ux7OyoPYlCNYRUZZNH40O9sqtCp1RkCy07Nlj9g2Hf9zbWxVgKnk4xZxh6gnXfZ fRF1BTTWTX78IQGuHXUKLOZfsN9sFPLUJPoX/k5CDmABh97PyCnBMQJfwYBPlZQ== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:23d4:b0:495:f519:70f0 with SMTP id 5614622812f47-4ad877f8f8bmr546381b6e.19.1785376765496; Wed, 29 Jul 2026 18:59:25 -0700 (PDT) Date: Wed, 29 Jul 2026 18:59:25 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a6aaffd.86abc875.e5c3d.005b.GAE@google.com> Subject: [syzbot] [sound?] possible deadlock in snd_seq_deliver_event (2) From: syzbot To: linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org, perex@perex.cz, syzkaller-bugs@googlegroups.com, tiwai@suse.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: fc02acf6ac0c Merge tag 'platform-drivers-x86-v7.2-4' of gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17a0b8c6580000 kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782 dashboard link: https://syzkaller.appspot.com/bug?extid=d4d7ac4a87bb2d52a822 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/67251350dd03/disk-fc02acf6.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/e4edd57a8c61/vmlinux-fc02acf6.xz kernel image: https://storage.googleapis.com/syzbot-assets/04ff166cc853/bzImage-fc02acf6.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+d4d7ac4a87bb2d52a822@syzkaller.appspotmail.com ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- kworker/1:3/5615 is trying to acquire lock: ffff888032c85128 (&grp->list_lock){.+.+}-{3:3}, at: __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:723 [inline] ffff888032c85128 (&grp->list_lock){.+.+}-{3:3}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline] ffff888032c85128 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x230/0x860 sound/core/seq/seq_clientmgr.c:813 but task is already holding lock: ffff8880269b0128 (&grp->list_lock){.+.+}-{3:3}, at: __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:723 [inline] ffff8880269b0128 (&grp->list_lock){.+.+}-{3:3}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline] ffff8880269b0128 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x230/0x860 sound/core/seq/seq_clientmgr.c:813 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&grp->list_lock); lock(&grp->list_lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/1:3/5615: #0: ffff88801bc0f140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc900039c7d08 ((work_completion)(&runtime->event_work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 #2: ffff8880269b0128 (&grp->list_lock){.+.+}-{3:3}, at: __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:723 [inline] #2: ffff8880269b0128 (&grp->list_lock){.+.+}-{3:3}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline] #2: ffff8880269b0128 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x230/0x860 sound/core/seq/seq_clientmgr.c:813 stack backtrace: CPU: 1 UID: 0 PID: 5615 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Workqueue: events snd_rawmidi_input_event_work Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_deadlock_bug.cold+0xbd/0xca kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x1256/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __raw_read_lock include/linux/rwlock_api_smp.h:163 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:232 __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:723 [inline] deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline] snd_seq_deliver_event+0x230/0x860 sound/core/seq/seq_clientmgr.c:813 snd_seq_kernel_client_dispatch+0x16f/0x1b0 sound/core/seq/seq_clientmgr.c:2439 queue_broadcast_event.isra.0+0x143/0x1b0 sound/core/seq/seq_queue.c:585 snd_seq_queue_process_event sound/core/seq/seq_queue.c:634 [inline] snd_seq_control_queue+0x709/0xb70 sound/core/seq/seq_queue.c:659 __snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:626 [inline] __snd_seq_deliver_single_event+0x127/0x1c0 sound/core/seq/seq_clientmgr.c:613 _snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:672 [inline] snd_seq_deliver_single_event+0x31f/0x8c0 sound/core/seq/seq_clientmgr.c:687 snd_seq_deliver_event+0x44b/0x860 sound/core/seq/seq_clientmgr.c:815 snd_seq_kernel_client_dispatch+0x16f/0x1b0 sound/core/seq/seq_clientmgr.c:2439 send_timer_event.isra.0+0x130/0x190 sound/core/seq/oss/seq_oss_timer.c:140 snd_seq_oss_timer_start+0x1db/0x320 sound/core/seq/oss/seq_oss_timer.c:161 send_midi_event sound/core/seq/oss/seq_oss_midi.c:576 [inline] snd_seq_oss_midi_input+0x467/0xa30 sound/core/seq/oss/seq_oss_midi.c:501 snd_seq_oss_event_input+0x194/0x250 sound/core/seq/oss/seq_oss_event.c:429 __snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:626 [inline] __snd_seq_deliver_single_event+0x127/0x1c0 sound/core/seq/seq_clientmgr.c:613 _snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:672 [inline] snd_seq_deliver_single_event+0x31f/0x8c0 sound/core/seq/seq_clientmgr.c:687 __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:735 [inline] deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline] snd_seq_deliver_event+0x2c1/0x860 sound/core/seq/seq_clientmgr.c:813 snd_seq_kernel_client_dispatch+0x16f/0x1b0 sound/core/seq/seq_clientmgr.c:2439 snd_midi_input_event+0x32f/0x470 sound/core/seq/seq_midi.c:93 snd_rawmidi_input_event_work+0x61/0x80 sound/core/rawmidi.c:127 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 --- 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@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup