INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=25810, c=25809, q=761) All QSes seen, last rcu_preempt kthread activity 10502 (4295015060-4295004558), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.3 R running task 26416 6441 6356 0x00000008 Call Trace: sched_show_task kernel/sched/core.c:5168 [inline] sched_show_task.cold+0x2e3/0x347 kernel/sched/core.c:5143 print_other_cpu_stall kernel/rcu/tree.c:1501 [inline] check_cpu_stall kernel/rcu/tree.c:1616 [inline] __rcu_pending kernel/rcu/tree.c:3390 [inline] rcu_pending kernel/rcu/tree.c:3452 [inline] rcu_check_callbacks.cold+0xd3f/0xdaa kernel/rcu/tree.c:2792 update_process_times+0x29/0x60 kernel/time/timer.c:1590 tick_sched_handle+0x7d/0x150 kernel/time/tick-sched.c:165 tick_sched_timer+0x3e/0x120 kernel/time/tick-sched.c:1223 __run_hrtimer kernel/time/hrtimer.c:1223 [inline] __hrtimer_run_queues+0x25c/0xbb0 kernel/time/hrtimer.c:1287 hrtimer_interrupt+0x1e6/0x5e0 kernel/time/hrtimer.c:1321 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline] smp_apic_timer_interrupt+0x117/0x5e0 arch/x86/kernel/apic/apic.c:1100 apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792 RIP: 0010:dst_check include/net/dst.h:474 [inline] RIP: 0010:sctp_transport_dst_check include/net/sctp/sctp.h:608 [inline] RIP: 0010:sctp_packet_config+0x265/0x9f0 net/sctp/output.c:105 RSP: 0018:ffff8880aeb078e8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 RAX: ffffffff88749780 RBX: ffff8880a1625968 RCX: 1ffffffff10e92f2 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff88749790 RBP: ffff8880a16256c0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88804af8c400 R13: 0000000000000001 R14: ffff88809b93f000 R15: ffff88804bf5b540 sctp_outq_flush+0x45e/0x2dd0 net/sctp/outqueue.c:879 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1787 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1179 [inline] sctp_do_sm+0x419/0x4a90 net/sctp/sm_sideeffect.c:1150 sctp_generate_heartbeat_event+0x1da/0x3f0 net/sctp/sm_sideeffect.c:391 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1279 expire_timers kernel/time/timer.c:1318 [inline] __run_timers kernel/time/timer.c:1636 [inline] __run_timers kernel/time/timer.c:1604 [inline] run_timer_softirq+0x52a/0x1390 kernel/time/timer.c:1649 __do_softirq+0x254/0x9bf kernel/softirq.c:288 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1015 do_softirq.part.0+0x103/0x160 kernel/softirq.c:332 do_softirq kernel/softirq.c:324 [inline] __local_bh_enable_ip+0x149/0x190 kernel/softirq.c:185 local_bh_enable include/linux/bottom_half.h:32 [inline] tun_rx_batched.isra.0+0x482/0x7a0 drivers/net/tun.c:1222 tun_get_user+0xcde/0x3880 drivers/net/tun.c:1581 tun_chr_write_iter+0xcf/0x179 drivers/net/tun.c:1608 call_write_iter include/linux/fs.h:1778 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x44e/0x630 fs/read_write.c:482 vfs_write+0x192/0x4e0 fs/read_write.c:544 SYSC_write fs/read_write.c:590 [inline] SyS_write+0xf2/0x210 fs/read_write.c:582 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x416361 RSP: 002b:00007f6a3fe40c60 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000507740 RCX: 0000000000416361 RDX: 000000000000007e RSI: 0000000020000280 RDI: 00000000000000f0 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00000000ffffffff R13: 0000000000000bb2 R14: 00000000004cdd84 R15: 00007f6a3fe416d4 rcu_preempt kthread starved for 10502 jiffies! g25810 c25809 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=1 rcu_preempt R running task 29536 8 2 0x80000000 Call Trace: schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x43c/0xe40 kernel/time/timer.c:1746 rcu_gp_kthread+0xb8e/0x1ce0 kernel/rcu/tree.c:2255 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 INFO: rcu_sched self-detected stall on CPU 1-...: (1 GPs behind) idle=53e/140000000000001/0 softirq=91866/91868 fqs=0 INFO: rcu_sched detected stalls on CPUs/tasks: (t=10541 jiffies g=14757 c=14756 q=2) 1-...: (1 GPs behind) idle=53e/140000000000001/0 softirq=91866/91868 fqs=0 rcu_sched kthread starved for 10541 jiffies! g14757 c14756 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0 rcu_sched R running task 29392 9 2 0x80000000 Call Trace: schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x43c/0xe40 kernel/time/timer.c:1746 rcu_gp_kthread+0xb8e/0x1ce0 kernel/rcu/tree.c:2255 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 (detected by 0, t=10541 jiffies, g=14757, c=14756, q=2) NMI backtrace for cpu 1 CPU: 1 PID: 6441 Comm: syz-executor.3 Not tainted 4.14.177-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:158 [inline] rcu_dump_cpu_stacks+0x16d/0x1b8 kernel/rcu/tree.c:1396 print_cpu_stall kernel/rcu/tree.c:1542 [inline] check_cpu_stall kernel/rcu/tree.c:1610 [inline] __rcu_pending kernel/rcu/tree.c:3390 [inline] rcu_pending kernel/rcu/tree.c:3452 [inline] rcu_check_callbacks.cold+0x490/0xdaa kernel/rcu/tree.c:2792 update_process_times+0x29/0x60 kernel/time/timer.c:1590 tick_sched_handle+0x7d/0x150 kernel/time/tick-sched.c:165 tick_sched_timer+0x3e/0x120 kernel/time/tick-sched.c:1223 __run_hrtimer kernel/time/hrtimer.c:1223 [inline] __hrtimer_run_queues+0x25c/0xbb0 kernel/time/hrtimer.c:1287 hrtimer_interrupt+0x1e6/0x5e0 kernel/time/hrtimer.c:1321 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline] smp_apic_timer_interrupt+0x117/0x5e0 arch/x86/kernel/apic/apic.c:1100 apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792 RIP: 0010:dst_check include/net/dst.h:474 [inline] RIP: 0010:sctp_transport_dst_check include/net/sctp/sctp.h:608 [inline] RIP: 0010:sctp_packet_config+0x265/0x9f0 net/sctp/output.c:105 RSP: 0018:ffff8880aeb078e8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 RAX: ffffffff88749780 RBX: ffff8880a1625968 RCX: 1ffffffff10e92f2 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff88749790 RBP: ffff8880a16256c0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88804af8c400 R13: 0000000000000001 R14: ffff88809b93f000 R15: ffff88804bf5b540 sctp_outq_flush+0x45e/0x2dd0 net/sctp/outqueue.c:879 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1787 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1179 [inline] sctp_do_sm+0x419/0x4a90 net/sctp/sm_sideeffect.c:1150 sctp_generate_heartbeat_event+0x1da/0x3f0 net/sctp/sm_sideeffect.c:391 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1279 expire_timers kernel/time/timer.c:1318 [inline] __run_timers kernel/time/timer.c:1636 [inline] __run_timers kernel/time/timer.c:1604 [inline] run_timer_softirq+0x52a/0x1390 kernel/time/timer.c:1649 __do_softirq+0x254/0x9bf kernel/softirq.c:288 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1015 do_softirq.part.0+0x103/0x160 kernel/softirq.c:332 do_softirq kernel/softirq.c:324 [inline] __local_bh_enable_ip+0x149/0x190 kernel/softirq.c:185 local_bh_enable include/linux/bottom_half.h:32 [inline] tun_rx_batched.isra.0+0x482/0x7a0 drivers/net/tun.c:1222 tun_get_user+0xcde/0x3880 drivers/net/tun.c:1581 tun_chr_write_iter+0xcf/0x179 drivers/net/tun.c:1608 call_write_iter include/linux/fs.h:1778 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x44e/0x630 fs/read_write.c:482 vfs_write+0x192/0x4e0 fs/read_write.c:544 SYSC_write fs/read_write.c:590 [inline] SyS_write+0xf2/0x210 fs/read_write.c:582 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x416361 RSP: 002b:00007f6a3fe40c60 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000507740 RCX: 0000000000416361 RDX: 000000000000007e RSI: 0000000020000280 RDI: 00000000000000f0 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00000000ffffffff R13: 0000000000000bb2 R14: 00000000004cdd84 R15: 00007f6a3fe416d4 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff8640b3ee rcu_sched kthread starved for 10596 jiffies! g14757 c14756 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0 rcu_sched R running task 29392 9 2 0x80000000 Call Trace: schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x43c/0xe40 kernel/time/timer.c:1746 rcu_gp_kthread+0xb8e/0x1ce0 kernel/rcu/tree.c:2255 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404