From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f205.google.com (mail-oi1-f205.google.com [209.85.167.205]) (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 1743947255E for ; Tue, 18 Aug 2026 12:48:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.205 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787057320; cv=none; b=rXpft2NqsTsJXa/oYsBbjTl5KrmJTwzeibpY5awXz1LJGnf271UQgRuuiPMCwISD7F7VrKvOhbewdqm8UFJRlBFIf6d4SwNUpPSXbk0ormd8vMCyXP4BqeafKTwx5R7ZoSSArLw/ytprwA/rePM9v5R8iQmE2gFuKiL3hizvITM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787057320; c=relaxed/simple; bh=ech2oALMamPuan97YeDS3PhS1KSCFjECOislDsNYNYk=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=aKCwZ6wghpYDVQnIpbK1hE1YGw24O4BGOAb/PDKNrtR6XKthxquEcGhYWZwldwg8mhVk0yt89j0RYq0OJElRttHZRwVOpuSSDmt5B44/qO3zxO5eoSsYqUguGppbVCT7nartpKVDN1KXktsGpuG9JRj3XVJpP2dBMfYveL189Ms= 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=209.85.167.205 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-f205.google.com with SMTP id 5614622812f47-4b28d8d14e0so1821703b6e.2 for ; Tue, 18 Aug 2026 05:48:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787057315; x=1787662115; 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=0J2uIduWTdgNCi8MtRtOEQXTELag7LQMcnHT/wbMP9U=; b=GeZjDl+e2hdi5iRM4tUfvuQJlm1jMmhWPBmpwAMrWRZVv4VCUXL3l/m8/FW8Ec4FDc j9+x0Zcdkt73Gx7S6XdE4v/Jj3PNPMTLJ7QHGclNG82E5PJuBWUqK6Mo7faxKkTh4Evg bBpGnblE8ZfetvdY7nG6o13clJZodeFA00q/UAfa5bKB9T7PS4BxyeOckpNxu84jQiRZ UYCTn0Abidt8vYhqoNObK3ysxlUL6yRjMbQpWTj5AaX91JaKLd3dcW9xQ5htMvL3ZUCd tB5i48B1oJ73IzOGQGfk+3z+3mIq1rd8Y4wJIv95waCa78/Bcx9Gas/4sm1i/IVTTZVj ZibA== X-Gm-Message-State: AOJu0YzlHUsZcX4ZCuqFiSMK3Hn19UCqn1nG7XHVPBKjvS5Th15i+e8A jcfhfm5NBdjnjcwk4r2f+1e2R67ezz0fTuV6zMVxSuKK3dJD3V4m+WeICFu7+aiQ7JVhvqwy+Pq oGJQ+X1aXG8PA9Xvt8WXlH+1628DgKkGuFI5Sz6jHkYw/XFICmuFESzbIiHBCjQ== 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:c40b:b0:4aa:cad:cb4d with SMTP id 5614622812f47-4b241e71110mr27557361b6e.19.1787057314958; Tue, 18 Aug 2026 05:48:34 -0700 (PDT) Date: Tue, 18 Aug 2026 05:48:34 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a8454a2.ae6ddae5.3da009.0001.GAE@google.com> Subject: [syzbot] [kernel?] possible deadlock in bh_worker From: syzbot To: linux-kernel@vger.kernel.org, peterz@infradead.org, syzkaller-bugs@googlegroups.com, tglx@kernel.org Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: dcb68831eac7 Merge tag 'block-7.2-20260815' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11c2d949580000 kernel config: https://syzkaller.appspot.com/x/.config?x=4c9eb8e593cf8c5c dashboard link: https://syzkaller.appspot.com/bug?extid=1bd20115328f8254ed62 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/1174a1aaa938/disk-dcb68831.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/c14ec1120394/vmlinux-dcb68831.xz kernel image: https://storage.googleapis.com/syzbot-assets/5971a3555672/bzImage-dcb68831.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+1bd20115328f8254ed62@syzkaller.appspotmail.com ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- ktimers/0/16 is trying to acquire lock: ffff8880b873a990 (&pool->cb_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] ffff8880b873a990 (&pool->cb_lock){+...}-{3:3}, at: worker_lock_callback kernel/workqueue.c:3144 [inline] ffff8880b873a990 (&pool->cb_lock){+...}-{3:3}, at: bh_worker+0x7d/0x880 kernel/workqueue.c:3688 but task is already holding lock: ffff8880b863a990 (&pool->cb_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] ffff8880b863a990 (&pool->cb_lock){+...}-{3:3}, at: worker_lock_callback kernel/workqueue.c:3144 [inline] ffff8880b863a990 (&pool->cb_lock){+...}-{3:3}, at: bh_worker+0x7d/0x880 kernel/workqueue.c:3688 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&pool->cb_lock); lock(&pool->cb_lock); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by ktimers/0/16: #0: ffffffff8e059220 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #1: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #2: ffff8880b863a990 (&pool->cb_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #2: ffff8880b863a990 (&pool->cb_lock){+...}-{3:3}, at: worker_lock_callback kernel/workqueue.c:3144 [inline] #2: ffff8880b863a990 (&pool->cb_lock){+...}-{3:3}, at: bh_worker+0x7d/0x880 kernel/workqueue.c:3688 #3: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #3: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #3: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #3: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 #4: ffff88813ff1dd38 ((wq_completion)events_bh){+...}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline] #4: ffff88813ff1dd38 ((wq_completion)events_bh){+...}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405 #5: ffffc90000157ba0 ((work_completion)(&dead_work.work)){+...}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline] #5: ffffc90000157ba0 ((work_completion)(&dead_work.work)){+...}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405 stack backtrace: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x24df/0x2ce0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] worker_lock_callback kernel/workqueue.c:3144 [inline] bh_worker+0x7d/0x880 kernel/workqueue.c:3688 drain_dead_softirq_workfn+0x95/0x220 kernel/workqueue.c:3763 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 bh_worker+0x46a/0x880 kernel/workqueue.c:3708 tasklet_action+0xc/0x70 kernel/softirq.c:965 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 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 BUG: workqueue leaked atomic, lock or RCU: ktimers/0[16] preempt=0x00000000 lock=4->0 RCU=2->2 workfn=drain_dead_softirq_workfn INFO: lockdep is turned off. CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 process_one_work kernel/workqueue.c:3343 [inline] process_scheduled_works+0x1161/0x14e0 kernel/workqueue.c:3405 bh_worker+0x46a/0x880 kernel/workqueue.c:3708 tasklet_action+0xc/0x70 kernel/softirq.c:965 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 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 --- This report is generated by a bot. It may contain errors. 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