Messages in this thread | | | Subject | Re: INFO: task hung in isig | From | Tetsuo Handa <> | Date | Fri, 18 May 2018 19:22:50 +0900 |
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syzbot wrote: > INFO: task kworker/u4:1:22 blocked for more than 120 seconds. > Not tainted 4.17.0-rc5+ #55 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > kworker/u4:1 D21192 22 2 0x80000000 > Workqueue: events_unbound flush_to_ldisc > Call Trace: > context_switch kernel/sched/core.c:2859 [inline] > __schedule+0x801/0x1e30 kernel/sched/core.c:3501 > schedule+0xef/0x430 kernel/sched/core.c:3545 > __rwsem_down_write_failed_common+0x919/0x15d0 kernel/locking/rwsem-xadd.c:566 > rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:595 > call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 > __down_write arch/x86/include/asm/rwsem.h:142 [inline] > down_write+0xa2/0x120 kernel/locking/rwsem.c:72
kworker/u4:1(PID=22) got stuck at
down_write(&tty->termios_rwsem);
> isig+0xcd/0x4e0 drivers/tty/n_tty.c:1098 > n_tty_receive_signal_char+0x22/0x120 drivers/tty/n_tty.c:1210 > n_tty_receive_char_special+0x1c27/0x31c0 drivers/tty/n_tty.c:1259 > n_tty_receive_buf_fast drivers/tty/n_tty.c:1577 [inline] > __receive_buf drivers/tty/n_tty.c:1611 [inline] > n_tty_receive_buf_common+0x20ca/0x2c50 drivers/tty/n_tty.c:1709 > n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1744 > tty_ldisc_receive_buf+0xb0/0x190 drivers/tty/tty_buffer.c:456 > tty_port_default_receive_buf+0x110/0x170 drivers/tty/tty_port.c:38 > receive_buf drivers/tty/tty_buffer.c:475 [inline] > flush_to_ldisc+0x3e9/0x560 drivers/tty/tty_buffer.c:524 > process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 > worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 > kthread+0x345/0x410 kernel/kthread.c:240 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
waiting for syz-executor3(PID=8572) which is stalling inside __process_echoes()
> CPU: 0 PID: 8572 Comm: syz-executor3 Not tainted 4.17.0-rc5+ #55 > Call Trace: > __process_echoes+0x2dc/0x8d0 drivers/tty/n_tty.c:732 > flush_echoes drivers/tty/n_tty.c:799 [inline] > __receive_buf drivers/tty/n_tty.c:1615 [inline]
after
down_read(&tty->termios_rwsem);
in n_tty_receive_buf_common().
> n_tty_receive_buf_common+0x11d5/0x2c50 drivers/tty/n_tty.c:1709 > n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1738 > tiocsti drivers/tty/tty_io.c:2171 [inline] > tty_ioctl+0x7e7/0x1870 drivers/tty/tty_io.c:2557 > vfs_ioctl fs/ioctl.c:46 [inline] > file_ioctl fs/ioctl.c:500 [inline] > do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684 > ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701 > __do_sys_ioctl fs/ioctl.c:708 [inline] > __se_sys_ioctl fs/ioctl.c:706 [inline] > __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706 > do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x49/0xbe
Therefore, this will be a dup of below report.
#syz dup: INFO: rcu detected stall in __process_echoes
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