From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f80.google.com (mail-ot1-f80.google.com [209.85.210.80]) (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 3617E2DB7AE for ; Tue, 13 Jan 2026 21:13:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.80 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768338810; cv=none; b=AG3RC4LagU+GeVFAJxyeE2kpj6/nRqagQhHrhUfu2h7fZr9zWU7vp4720FGOPHTHnSZJSnxSZ7000+FJT3rb09NI8wdRi7U+H5Giu1DxBs45EKccFyFFybnSp4Moe6gPr+5eZ67wx+8C3vrWlH+CrVSjR7JNPC9kjZmUepFhmdM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768338810; c=relaxed/simple; bh=kkfYM9rcmzJqoKTEVUFgB3A/3RIlE2BUbnPkJCE0pb4=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=QNDBhTh2Rn5VlWjFo04ALt69Iodu1tDdygL4SQx4WjqsRNGd9tymgoVoSg0VTbsym7R32LsyEw8GzEDk0D76PHZSZXU9RCbjBZKsp1YqzVqGxFakFyG2yajyJ10JP8WqIMPOJF5bZOok7dsB0L0QCU1q8Wmn4xqqLpt1iJYZPc0= 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=209.85.210.80 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-ot1-f80.google.com with SMTP id 46e09a7af769-7c70930bdf4so15031133a34.2 for ; Tue, 13 Jan 2026 13:13:29 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768338808; x=1768943608; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=ww9K08WdfheEaoLlst1by6MXgbFiqGH2FsG5ZH83AiU=; b=vDuIvg4Yk8pX6+IKHml/gSBTVtVBVO3aEgYDSu2ckEA81zrvub3HqctQngXSH/9JWL lgEIKp+qyYJoUIkJLKDED/8mmgDU4V3ubisyDnZe5PcUoj8tmof4f9Sh5SYndEWFHExV TnelPKgtcltnsRj/auoO9DWqKpicQOM2kMJL7aFbvvwKXEYyhBVEBV2r4ZK74P/eKHUF M3PIE6mnrPCLlvauJig4JNDpqMpTw4j5Pog7L7MsfkW8TvO28v2HjvK6zwDjc6H/duP6 wZx4d33shV0NEB+8jA4vEl7MLoQvWkjq+v74NnTPuWOTUlNuF8INuWpHflHOVjqat82V H6cA== X-Forwarded-Encrypted: i=1; AJvYcCVvcfxJKEoONLpCInYlsl649t1so1p5A/ywQpfdVzxsw3eQl5Q9IRAbXke87awrAr60cyZnba8ITw==@vger.kernel.org X-Gm-Message-State: AOJu0Yxyy/CoQ/pq7DMvq15XtTvbYgGGYkNMkF3RYMgg/ZDhOLhkiJia iBQap+SO1SxY+ChDUZ1VM+oL3TmglALtV5iYWScKlxeKJHalczRem7i7Xg/ckDY6WoJipwZf6qt XOZP8WS4mwR1XayCX0BhK+DAAp1WyTRl0opvdr/aPq3l1hJdskDLIXXRAS9A= Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:161e:b0:65f:6cf5:f963 with SMTP id 006d021491bc7-661006767e1mr324854eaf.6.1768338808243; Tue, 13 Jan 2026 13:13:28 -0800 (PST) Date: Tue, 13 Jan 2026 13:13:28 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6966b578.a70a0220.245e30.0004.GAE@google.com> Subject: [syzbot] [io-uring?] INFO: rcu detected stall in io_ring_exit_work (3) From: syzbot To: axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: f0b9d8eb98df Merge tag 'nfsd-6.19-3' of git://git.kernel.o.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17eba922580000 kernel config: https://syzkaller.appspot.com/x/.config?x=a11e0f726bfb6765 dashboard link: https://syzkaller.appspot.com/bug?extid=33504742c13bcd6c9541 compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, 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/4dbba2a806a3/disk-f0b9d8eb.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/2a52c0f94de7/vmlinux-f0b9d8eb.xz kernel image: https://storage.googleapis.com/syzbot-assets/5ddf9a24988b/bzImage-f0b9d8eb.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+33504742c13bcd6c9541@syzkaller.appspotmail.com rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7809/1:b..l rcu: (detected by 0, t=10503 jiffies, g=47705, q=685 ncpus=2) task:kworker/u8:22 state:R running task stack:23544 pid:7809 tgid:7809 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: iou_exit io_ring_exit_work Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:unwind_next_frame+0x162b/0x20b0 arch/x86/kernel/unwind_orc.c:680 Code: 00 00 fc ff df 80 3c 02 00 0f 84 31 f8 ff ff 4c 89 e7 e8 58 f3 bb 00 e9 24 f8 ff ff 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 <48> c1 ea 03 80 3c 02 00 0f 85 a8 05 00 00 49 8d 7d 08 49 8b 5d 38 RSP: 0018:ffffc9000c7e7558 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffc9000c7e8000 RDX: ffffc9000c7e7600 RSI: ffffc9000c7e79e0 RDI: ffffc9000c7e7608 RBP: ffffc9000c7e7bd0 R08: 0000000000000001 R09: 0000000077ba390a R10: 0000000000000002 R11: 000000000003a058 R12: ffffc9000c7e7618 R13: ffffc9000c7e75c8 R14: ffffc9000c7e7a10 R15: ffffc9000c7e75fc arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kmalloc_noprof include/linux/slab.h:957 [inline] slab_free_hook mm/slub.c:2492 [inline] slab_free mm/slub.c:6670 [inline] kmem_cache_free+0x147/0x770 mm/slub.c:6781 __io_req_caches_free+0x19e/0x5c0 io_uring/io_uring.c:2827 io_req_caches_free io_uring/io_uring.c:2839 [inline] io_ring_exit_work+0x33c/0x1170 io_uring/io_uring.c:3025 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: rcu_preempt kthread starved for 10528 jiffies! g47705 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:28328 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 12129 Comm: syz.5.1498 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202 Code: 90 f3 0f 1e fa 53 48 8b 74 24 08 48 89 fb 48 83 c7 18 e8 7a fe 1e f6 48 89 df e8 32 51 1f f6 e8 9d 14 4c f6 fb bf 01 00 00 00 42 54 0f f6 65 8b 05 9b b9 37 08 85 c0 74 06 5b e9 01 4d 00 00 RSP: 0018:ffffc9000ec8fca0 EFLAGS: 00000202 RAX: 0000000007584837 RBX: ffff888031ace5c0 RCX: ffffffff81c70a2f RDX: 0000000000000000 RSI: ffffffff8dace031 RDI: 0000000000000001 RBP: ffff888031ace9c0 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff9088b8d7 R11: ffff88802bec0b30 R12: 0000000000000000 R13: 0000000000000021 R14: 0000000000000400 R15: ffff888031ace5c0 FS: 00007fc1128de6c0(0000) GS:ffff8881248f5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc1128de040 CR3: 0000000043610000 CR4: 00000000003526f0 Call Trace: spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x1e6a/0x26d0 kernel/signal.c:3037 arch_do_signal_or_restart+0x8f/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x8c/0x540 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc11198f747 Code: ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 RSP: 002b:00007fc1128de0e8 EFLAGS: 00000246 RAX: 00000000000000ca RBX: 00007fc111be6098 RCX: 00007fc11198f749 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fc111be6098 RBP: 00007fc111be6090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc111be6128 R14: 00007fff61d0e6b0 R15: 00007fff61d0e798 --- This report is generated by a bot. 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