On Mon, May 22, 2017 at 9:39 AM, Sergey Senozhatsky
<sergey.senozhatsky.work@xxxxxxxxx> wrote:
>
> [ 1274.378287] ======================================================
> [ 1274.378289] WARNING: possible circular locking dependency detected
> [ 1274.378290] 4.12.0-rc1-next-20170522-dbg-00007-gc09b2ab28b74-dirty #1317 Not tainted
> [ 1274.378291] ------------------------------------------------------
> [ 1274.378293] kworker/u8:5/111 is trying to acquire lock:
> [ 1274.378294] (&buf->lock){+.+...}, at: [<ffffffff812f2831>] tty_buffer_flush+0x34/0x88
> [ 1274.378300]
> but task is already holding lock:
> [ 1274.378301] (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff812ee5c7>] isig+0x47/0xd2
> [ 1274.378307]
> which lock already depends on the new lock.
>
> [ 1274.378309]
> the existing dependency chain (in reverse order) is:
> [ 1274.378310]
> -> #2 (&o_tty->termios_rwsem/1){++++..}:
> [ 1274.378316] lock_acquire+0x183/0x1ae
> [ 1274.378319] down_read+0x3e/0x62
> [ 1274.378321] n_tty_write+0x6c/0x3d6
> [ 1274.378322] tty_write+0x1cc/0x25f
> [ 1274.378325] __vfs_write+0x26/0xec
> [ 1274.378327] vfs_write+0xe1/0x16a
> [ 1274.378329] SyS_write+0x51/0x8e
> [ 1274.378330] entry_SYSCALL_64_fastpath+0x18/0xad
> [ 1274.378331]
> -> #1 (&tty->atomic_write_lock){+.+.+.}:
> [ 1274.378335] lock_acquire+0x183/0x1ae
> [ 1274.378337] __mutex_lock+0x95/0x7ba
> [ 1274.378339] mutex_lock_nested+0x1b/0x1d
> [ 1274.378340] tty_port_default_receive_buf+0x4e/0x81
> [ 1274.378342] flush_to_ldisc+0x87/0xa1
> [ 1274.378345] process_one_work+0x2be/0x52b
> [ 1274.378346] worker_thread+0x1f3/0x2c5
> [ 1274.378349] kthread+0x131/0x139
> [ 1274.378350] ret_from_fork+0x2e/0x40
> [ 1274.378351]
> -> #0 (&buf->lock){+.+...}:
> [ 1274.378355] __lock_acquire+0xec4/0x1444
> [ 1274.378357] lock_acquire+0x183/0x1ae
> [ 1274.378358] __mutex_lock+0x95/0x7ba
> [ 1274.378360] mutex_lock_nested+0x1b/0x1d
> [ 1274.378362] tty_buffer_flush+0x34/0x88
> [ 1274.378364] pty_flush_buffer+0x27/0x70
> [ 1274.378366] tty_driver_flush_buffer+0x1b/0x1e
> [ 1274.378367] isig+0x9b/0xd2
> [ 1274.378369] n_tty_receive_signal_char+0x1c/0x59
> [ 1274.378371] n_tty_receive_char_special+0xa4/0x740
> [ 1274.378373] n_tty_receive_buf_common+0x452/0x810
> [ 1274.378374] n_tty_receive_buf2+0x14/0x16
> [ 1274.378376] tty_ldisc_receive_buf+0x1f/0x4a
> [ 1274.378377] tty_port_default_receive_buf+0x5f/0x81
> [ 1274.378379] flush_to_ldisc+0x87/0xa1
> [ 1274.378380] process_one_work+0x2be/0x52b
> [ 1274.378382] worker_thread+0x1f3/0x2c5
> [ 1274.378383] kthread+0x131/0x139
> [ 1274.378385] ret_from_fork+0x2e/0x40
> [ 1274.378386]
> other info that might help us debug this:
JFTR, I'm also seeing this on various arm/arm64 platforms.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
