Not tainted 4.13.0-rc6-next-20170825+ #9 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syzkaller426058 D22912 3038 3036 0x00000000 Call Trace: context_switch kernel/sched/core.c:2792 [inline] __schedule+0x8e8/0x2070 kernel/sched/core.c:3371 schedule+0x108/0x440 kernel/sched/core.c:3430 __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+0x92/0xc0 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+0x7d5/0x1630 fs/splice.c:1398 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x434f69 RSP: 002b:00007ffe7df8c2a8 EFLAGS: 00000207 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00000000004002b0 RCX: 0000000000434f69 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000086 R08: 000000000000001f R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000207 R12: 0000000000000000 R13: 00000000004018e0 R14: 0000000000401970 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/664: #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:4552 1 lock held by rsyslogd/2924: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0x131/0x1a0 fs/file.c:767 2 locks held by getty/3007: #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+0x2f2/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/3008: #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+0x2f2/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/3009: #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+0x2f2/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/3010: #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+0x2f2/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/3011: #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+0x2f2/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/3012: #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+0x2f2/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/3013: #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+0x2f2/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by syzkaller426058/3038: #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 2 CPU: 2 PID: 664 Comm: khungtaskd Not tainted 4.13.0-rc6-next-20170825+ #9 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 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+0x39c/0x470 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431 Sending NMI from CPU 2 to CPUs 0-1,3: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff84da2b86 NMI backtrace for cpu 3 skipped: idling at pc 0xffffffff84da2b86 NMI backtrace for cpu 0 CPU: 0 PID: 2921 Comm: rs:main Q:Reg Not tainted 4.13.0-rc6-next-20170825+ #9 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88003ad1e700 task.stack: ffff88003d708000 RIP: 0010:is_last_frame arch/x86/kernel/unwind_frame.c:100 [inline] RIP: 0010:is_last_task_frame arch/x86/kernel/unwind_frame.c:169 [inline] RIP: 0010:unwind_next_frame.part.6+0xde/0xc70 arch/x86/kernel/unwind_frame.c:267 RSP: 0018:ffff88003d70f610 EFLAGS: 00000046 RAX: dffffc0000000000 RBX: ffff88003d70f740 RCX: ffff88003d70f790 RDX: 1ffff10007ae1eef RSI: ffffffff81aa487f RDI: ffff88003d70f740 RBP: ffff88003d70f718 R08: ffff88003d70f780 R09: ffff88003d70f778 R10: ffff88003d70f6f0 R11: 1ffff100075a3f73 R12: 1ffff10007ae1eca R13: 0000000000000000 R14: ffff88003ad1e700 R15: ffff88003ad1efe0 FS: 00007f10ad008700(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055f094e23008 CR3: 000000003a5e5000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: unwind_next_frame+0x3e/0x50 arch/x86/kernel/unwind_frame.c:260 __save_stack_trace+0x6e/0xd0 arch/x86/kernel/stacktrace.c:44 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 add_xhlock kernel/locking/lockdep.c:4862 [inline] check_add_xhlock kernel/locking/lockdep.c:4885 [inline] lock_acquire_crosslock kernel/locking/lockdep.c:4957 [inline] __lock_acquire+0x20f4/0x4620 kernel/locking/lockdep.c:3501 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:35 [inline] percpu_down_read include/linux/percpu-rwsem.h:58 [inline] __sb_start_write+0x18f/0x290 fs/super.c:1340 file_start_write include/linux/fs.h:2672 [inline] vfs_write+0x410/0x510 fs/read_write.c:517 SYSC_write fs/read_write.c:565 [inline] SyS_write+0xef/0x220 fs/read_write.c:557 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x7f10aea6619d RSP: 002b:00007f10ad007000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000098 RCX: 00007f10aea6619d RDX: 0000000000000098 RSI: 0000000001d25a90 RDI: 0000000000000005 RBP: 0000000000000086 R08: 0a3a332c312d3020 R09: 676e69646e655320 R10: 0000000000000000 R11: 0000000000000293 R12: 00007f10ae3f9973 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000040 Code: 92 09 00 00 41 f6 85 88 00 00 00 03 0f 85 65 02 00 00 4c 8d 4b 38 48 b8 00 00 00 00 00 fc ff df 4c 89 ca 48 c1 ea 03 80 3c 02 00 <0f> 85 be 09 00 00 4c 8d 43 28 48 ba 00 00 00 00 00 fc ff df 48