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:27600 pid:12 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5246 [inline] __schedule+0x107f/0x4030 kernel/sched/core.c:6563 schedule+0xb9/0x180 kernel/sched/core.c:6639 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+0x49f/0xac0 kernel/rcu/tasks.h:693 rcu_tasks_one_gp+0xd27/0xef0 kernel/rcu/tasks.h:534 rcu_tasks_kthread+0x6e/0x90 kernel/rcu/tasks.h:562 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: 1 lock held by rcu_tasks_kthre/12: #0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517 1 lock held by rcu_tasks_trace/13: #0: ffffffff8cb2ed10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517 1 lock held by khungtaskd/28: #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527 2 locks held by getty/4030: #0: ffff88814cfe2098 (&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+0x41e/0x1360 drivers/tty/n_tty.c:2198 2 locks held by kworker/1:4/4319: #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #1: ffffc90004117d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 3 locks held by kworker/u4:4/31218: #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #1: ffffc9000ce5fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #2: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263 1 lock held by syz.2.9692/9139: 3 locks held by syz.2.9714/9197: 2 locks held by syz.1.9746/9316: #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline] #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3495 #1: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline] #1: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2ec/0x890 kernel/rcu/tree_exp.h:962 1 lock held by syz.4.9749/9323: #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline] #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3495 1 lock held by syz.4.9749/9326: #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x5e7/0xe80 net/core/dev_ioctl.c:596 1 lock held by syz.0.9752/9342: #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x5e7/0xe80 net/core/dev_ioctl.c:596 1 lock held by syz.0.9752/9343: #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: __netlink_dump_start+0x11e/0x6f0 net/netlink/af_netlink.c:2310 1 lock held by syz.5.9754/9348: #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x5e7/0xe80 net/core/dev_ioctl.c:596 ============================================= 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 07/24/2026 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: 9197 Comm: syz.2.9714 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:rcu_read_lock_sched include/linux/rcupdate.h:884 [inline] RIP: 0010:pfn_valid+0x101/0x420 include/linux/mmzone.h:1857 Code: d2 b9 02 00 00 00 45 31 c0 45 31 c9 53 e8 b7 3e 86 ff 48 83 c4 08 e8 3e 64 52 08 89 c5 31 ff 89 c6 e8 93 77 a4 ff 85 ed 74 1a 6a 6e 8e ff 84 c0 74 7d e8 21 74 a4 ff 4d 85 ff 75 11 e8 17 74 RSP: 0018:ffffc900034c7418 EFLAGS: 00000202 RAX: ffffffff81ddb9ed RBX: ffffffff81ddb9bd RCX: 0000000000000000 RDX: ffff88801c76bc00 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff2162048 R10: dffffc0000000000 R11: fffffbfff2162049 R12: dffffc0000000000 R13: ffffea00013fc140 R14: 000000000004ff05 R15: ffff88813fff9120 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555572edc4e8 CR3: 000000001dff9000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: page_table_check_clear+0x1e/0x6b0 mm/page_table_check.c:67 ptep_get_and_clear_full arch/x86/include/asm/jump_label.h:-1 [inline] zap_pte_range mm/memory.c:1433 [inline] zap_pmd_range mm/memory.c:1572 [inline] zap_pud_range mm/memory.c:1601 [inline] zap_p4d_range mm/memory.c:1622 [inline] unmap_page_range+0x1905/0x25b0 mm/memory.c:1643 unmap_vmas+0x260/0x390 mm/memory.c:1728 exit_mmap+0x20d/0x970 mm/mmap.c:3250 __mmput+0x118/0x3a0 kernel/fork.c:1206 exit_mm+0x24d/0x350 kernel/exit.c:572 do_exit+0x958/0x2570 kernel/exit.c:874 do_group_exit+0x229/0x2e0 kernel/exit.c:1030 get_signal+0x1259/0x1340 kernel/signal.c:2880 arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1485 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0033:0x7f24b2e53bd7 Code: Unable to access opcode bytes at 0x7f24b2e53bad. RSP: 002b:00007f24b3ef8120 EFLAGS: 00010202 RAX: 0000000000000000 RBX: 000000000000000b RCX: 00007f24b2f9e0d9 RDX: 00007f24b3ef8140 RSI: 00007f24b3ef8270 RDI: 000000000000000b RBP: 00007f24b3035024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007f24b3226038 R14: 00007f24b3225fa0 R15: 00007ffd3402cbc8