watchdog: BUG: soft lockup - CPU#1 stuck for 246s! [kworker/1:2:289] Modules linked in: CPU: 1 PID: 289 Comm: kworker/1:2 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: events fqdir_free_fn RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline] RIP: 0010:smp_call_function_single+0x1f5/0x470 kernel/smp.c:758 Code: 48 44 89 f6 83 e6 01 31 ff e8 47 49 0a 00 41 83 e6 01 49 bc 00 00 00 00 00 fc ff df 75 0a e8 82 45 0a 00 e9 a9 00 00 00 f3 90 44 24 48 01 00 00 00 0f 84 94 00 00 00 e8 68 45 0a 00 eb e9 e8 RSP: 0018:ffffc90000aa7ba0 EFLAGS: 00000293 RAX: ffffffff815e79e8 RBX: 0000000000000000 RCX: ffff888126fc93c0 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90000aa7c98 R08: dffffc0000000000 R09: ffffed103ee071d9 R10: ffffed103ee071d9 R11: 1ffff1103ee071d8 R12: dffffc0000000000 R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff92000154f78 FS: 0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6bd178e000 CR3: 00000001a2280000 CR4: 00000000003506a0 DR0: 0000000000000002 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: rcu_barrier+0x213/0x400 kernel/rcu/tree.c:4129 fqdir_free_fn+0x32/0x140 net/ipv4/inet_fragment.c:163 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472 kthread+0x411/0x500 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 1172 Comm: syz.4.220 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:native_halt arch/x86/include/asm/irqflags.h:57 [inline] RIP: 0010:halt arch/x86/include/asm/irqflags.h:98 [inline] RIP: 0010:kvm_wait+0xcc/0x140 arch/x86/kernel/kvm.c:912 Code: 20 f6 44 24 21 02 75 24 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 48 0f b6 07 40 38 f0 75 a6 66 90 0f 00 2d b5 91 d6 03 f4 9a fa 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 3f 0f b6 07 RSP: 0018:ffffc900011d71a0 EFLAGS: 00000046 RAX: 0000000000000003 RBX: ffff888100276bac RCX: ffffffff814f42f9 RDX: 0000000000000001 RSI: 0000000000000003 RDI: ffff888100276bac RBP: ffffc900011d7230 R08: dffffc0000000000 R09: ffffed102004ed76 R10: ffffed102004ed76 R11: 1ffff1102004ed75 R12: 1ffff1103ee00001 R13: ffff8881f7038ad4 R14: dffffc0000000000 R15: 1ffff9200023ae34 FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c230000 CR3: 000000018ab34000 CR4: 00000000003506b0 DR0: 0000000000000002 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: pv_wait arch/x86/include/asm/paravirt.h:597 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x60f/0x9c0 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline] queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock include/linux/spinlock.h:188 [inline] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:129 [inline] _raw_spin_lock_irq+0xd9/0xe0 kernel/locking/spinlock.c:170 get_wchan kernel/sched/core.c:2021 [inline] perf_trace_sched_blocked_reason+0x243/0x4a0 include/trace/events/sched.h:490 trace_sched_blocked_reason include/trace/events/sched.h:490 [inline] try_to_wake_up+0xea1/0x1160 kernel/sched/core.c:4190 wake_up_process kernel/sched/core.c:4348 [inline] wake_up_q+0xdf/0x1c0 kernel/sched/core.c:975 __mutex_unlock_slowpath+0x262/0x3b0 kernel/locking/mutex.c:923 mutex_unlock+0xd8/0x220 kernel/locking/mutex.c:557 rcu_barrier+0x3ba/0x400 kernel/rcu/tree.c:-1 netdev_run_todo+0x10d/0x990 net/core/dev.c:10670 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112 tun_detach drivers/net/tun.c:705 [inline] tun_chr_close+0xc4/0x140 drivers/net/tun.c:3440 __fput+0x20b/0x8b0 fs/file_table.c:311 ____fput+0x15/0x20 fs/file_table.c:339 task_work_run+0x127/0x190 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xa7e/0x27a0 kernel/exit.c:889 do_group_exit+0x141/0x310 kernel/exit.c:1003 get_signal+0x66a/0x1480 kernel/signal.c:2907 arch_do_signal_or_restart+0xc1/0x10f0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0xa7/0xe0 kernel/entry/common.c:178 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f43cc7eb749 Code: Unable to access opcode bytes at RIP 0x7f43cc7eb71f. RSP: 002b:00007f43cb211038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: 0000000000000000 RBX: 00007f43cca42180 RCX: 00007f43cc7eb749 RDX: 0000200000000080 RSI: 0000000000008914 RDI: 0000000000000011 RBP: 00007f43cc86ff91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f43cca42218 R14: 00007f43cca42180 R15: 00007ffcdc654f08