INFO: task rcu_tasks_kthre:12 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:rcu_tasks_kthre state:D stack:27808 pid:12 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5257 [inline] __schedule+0x1089/0x4140 kernel/sched/core.c:6584 schedule+0xb9/0x180 kernel/sched/core.c:6660 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2144 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x2c2/0x590 kernel/sched/completion.c:138 __synchronize_srcu+0x2b3/0x350 kernel/rcu/srcutree.c:1243 rcu_tasks_wait_gp+0x49d/0xb00 kernel/rcu/tasks.h:719 rcu_tasks_one_gp+0xb1c/0xce0 kernel/rcu/tasks.h:560 rcu_tasks_kthread+0x6e/0x90 kernel/rcu/tasks.h:588 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Showing all locks held in the system: 3 locks held by kworker/u4:1/11: #0: ffff888018479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #1: ffffc90000107d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #2: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263 1 lock held by rcu_tasks_kthre/12: #0: ffffffff8db2e3f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xce0 kernel/rcu/tasks.h:543 1 lock held by rcu_tasks_trace/13: #0: ffffffff8db2ec30 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xce0 kernel/rcu/tasks.h:543 1 lock held by khungtaskd/28: #0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6669 5 locks held by kworker/u4:5/2980: 2 locks held by getty/4028: #0: ffff888031bc9098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x430/0x1400 drivers/tty/n_tty.c:2198 2 locks held by kworker/u4:26/5988: #0: ffff8880b8d3ad18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:549 #1: ffff8880b8d27888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x400/0x740 kernel/sched/psi.c:999 2 locks held by kworker/1:0/14457: #0: ffff888018472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #1: ffffc90005e77d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 3 locks held by kworker/u4:19/14725: #0: ffff888018479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #1: ffffc9001bda7d00 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #2: ffffffff8db337b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline] #2: ffffffff8db337b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3c0/0x890 kernel/rcu/tree_exp.h:962 2 locks held by syz.4.2628/14891: #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline] #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3506 #1: ffffffff8db337b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline] #1: ffffffff8db337b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3c0/0x890 kernel/rcu/tree_exp.h:962 1 lock held by syz.3.2637/14932: #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1ed0 drivers/net/tun.c:3118 1 lock held by syz.3.2637/14933: #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1ed0 drivers/net/tun.c:3118 1 lock held by syz.5.2638/14937: #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline] #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163 2 locks held by syz.5.2638/14942: #0: ffffffff8edcc730 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:860 #1: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: nl80211_pre_doit+0x5a/0x890 net/wireless/nl80211.c:16390 1 lock held by syz.1.2639/14941: #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline] #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163 2 locks held by syz.1.2639/14947: #0: ffffffff8edcc730 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:860 #1: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: nl80211_pre_doit+0x5a/0x890 net/wireless/nl80211.c:16390 1 lock held by syz.2.2641/14949: #0: ffffffff8db82da8 (event_mutex){+.+.}-{3:3}, at: perf_trace_destroy+0x2a/0x140 kernel/trace/trace_event_perf.c:239 1 lock held by syz.2.2641/14951: #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline] #0: ffffffff8ed6b9e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline] watchdog+0xf0e/0xf50 kernel/hung_task.c:377 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 14725 Comm: kworker/u4:19 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 Workqueue: events_unbound nsim_dev_trap_report_work RIP: 0010:mark_lock+0x104/0x320 kernel/locking/lockdep.c:4725 Code: c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 34 f5 6e 00 b8 01 00 00 00 45 85 27 74 50 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d e8 b6 fb a8 02 85 c0 74 c1 48 c7 c0 38 76 22 8f 48 c1 e8 03 42 RSP: 0018:ffffc9001bda77b8 EFLAGS: 00000086 RAX: 0000000000000001 RBX: ffff888031051e00 RCX: ffffffff8164d6e4 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff91b62330 RBP: ffffc9001bda7868 R08: ffffffff91b62337 R09: 1ffffffff236c466 R10: dffffc0000000000 R11: fffffbfff236c467 R12: ffff888031052978 R13: 0000000000000003 R14: 1ffff1100620a51b R15: ffff888031052958 FS: 0000000000000000(0000) GS:ffff8880b8d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2b5c13 CR3: 000000007899b000 CR4: 00000000003506e0 DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000200000000240 DR3: 0000200000000240 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: mark_held_locks kernel/locking/lockdep.c:4302 [inline] __trace_hardirqs_on_caller kernel/locking/lockdep.c:4328 [inline] lockdep_hardirqs_on_prepare+0x380/0x7c0 kernel/locking/lockdep.c:4387 trace_hardirqs_on+0x34/0x40 kernel/trace/trace_preemptirq.c:49 crng_make_state+0x4ee/0xb00 drivers/char/random.c:353 _get_random_bytes+0xfc/0x250 drivers/char/random.c:366 eth_random_addr include/linux/etherdevice.h:232 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:756 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline] nsim_dev_trap_report_work+0x313/0xa80 drivers/net/netdevsim/dev.c:851 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295