Not tainted 4.13.0-rc6+ #23 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syzkaller517387 D23296 3011 3009 0x00000000 Call Trace: context_switch kernel/sched/core.c:2771 [inline] __schedule+0x8e8/0x2070 kernel/sched/core.c:3332 schedule+0x108/0x440 kernel/sched/core.c:3391 __lock_sock+0x1dc/0x2f0 net/core/sock.c:2245 lock_sock_nested+0xf3/0x110 net/core/sock.c:2766 lock_sock include/net/sock.h:1459 [inline] tcp_sendmsg+0x21/0x50 net/ipv4/tcp.c:1447 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:633 [inline] sock_sendmsg+0xca/0x110 net/socket.c:643 kernel_sendmsg+0x47/0x60 net/socket.c:651 sock_no_sendpage+0x1cc/0x280 net/core/sock.c:2574 tcp_sendpage_locked+0x10b/0x160 net/ipv4/tcp.c:1055 tcp_sendpage+0x43/0x60 net/ipv4/tcp.c:1070 inet_sendpage+0x1aa/0x660 net/ipv4/af_inet.c:779 kernel_sendpage+0x8d/0xe0 net/socket.c:3387 sock_sendpage+0x8c/0xc0 net/socket.c:858 pipe_to_sendpage+0x290/0x3b0 fs/splice.c:467 splice_from_pipe_feed fs/splice.c:518 [inline] __splice_from_pipe+0x343/0x750 fs/splice.c:642 splice_from_pipe+0x1e9/0x330 fs/splice.c:677 generic_splice_sendpage+0x40/0x50 fs/splice.c:848 do_splice_from fs/splice.c:867 [inline] do_splice fs/splice.c:1163 [inline] SYSC_splice fs/splice.c:1418 [inline] SyS_splice+0x7b7/0x1610 fs/splice.c:1398 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x43fd59 RSP: 002b:00007ffcbfb19c98 EFLAGS: 00000212 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fd59 RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 0000000000000086 R08: 0000000810000004 R09: 000000000000000a R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004016c0 R13: 0000000000401750 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/636: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0xd2/0x410 kernel/locking/lockdep.c:4417 1 lock held by rsyslogd/2898: #0: (&f->f_pos_lock){+.+.+.}, at: [] __fdget_pos+0x12b/0x190 fs/file.c:767 2 locks held by getty/2980: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2981: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2982: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2983: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2984: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2985: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2986: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by syzkaller517387/3011: #0: (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock_nested fs/pipe.c:66 [inline] #0: (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock+0x56/0x70 fs/pipe.c:74 #1: (sk_lock-AF_INET){+.+.+.}, at: [] lock_sock include/net/sock.h:1459 [inline] #1: (sk_lock-AF_INET){+.+.+.}, at: [] tcp_sendpage+0x2e/0x60 net/ipv4/tcp.c:1069 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 636 Comm: khungtaskd Not tainted 4.13.0-rc6+ #23 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 nmi_cpu_backtrace+0x20e/0x240 lib/nmi_backtrace.c:102 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:61 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 trigger_all_cpu_backtrace include/linux/nmi.h:105 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x35e/0x430 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:425 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.13.0-rc6+ #23 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffffffff85a2c340 task.stack: ffffffff85a00000 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:814 [inline] RIP: 0010:lock_is_held_type+0x18b/0x210 kernel/locking/lockdep.c:3895 RSP: 0018:ffff8801db207620 EFLAGS: 00000086 RAX: dffffc0000000000 RBX: 0000000000000086 RCX: 1ffff1003b664c1e RDX: 1ffffffff0b59431 RSI: ffff8801db325798 RDI: 0000000000000086 RBP: ffff8801db207640 R08: ffff88021fff901c R09: ffff88021fff9008 R10: ffff88021fff9010 R11: ffff88021fff901d R12: ffffffff85a2c340 R13: 0000000000000001 R14: 00000000000007ff R15: ffff8801db207988 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055d7307e10d0 CR3: 00000001ce66f000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_is_held include/linux/lockdep.h:348 [inline] detach_tasks kernel/sched/fair.c:6755 [inline] load_balance+0x1ac8/0x3eb0 kernel/sched/fair.c:8073 rebalance_domains+0x786/0xcc0 kernel/sched/fair.c:8688 run_rebalance_domains+0x39d/0x7c0 kernel/sched/fair.c:8910 __do_softirq+0x2f5/0xba3 kernel/softirq.c:284 invoke_softirq kernel/softirq.c:364 [inline] irq_exit+0x1cc/0x200 kernel/softirq.c:405 scheduler_ipi+0x165/0x460 kernel/sched/core.c:1785 __smp_reschedule_interrupt arch/x86/kernel/smp.c:262 [inline] smp_reschedule_interrupt+0x61/0x80 arch/x86/kernel/smp.c:268 reschedule_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:726 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53 RSP: 0018:ffffffff85a07ce0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff0b40f9f RCX: 0000000000000000 RDX: 1ffffffff0b59434 RSI: 0000000000000001 RDI: ffffffff85aca1a0 RBP: ffffffff85a07ce0 R08: ffffffff85810a80 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff85aca190