Messages in this thread Patch in this message | | | Date | Thu, 24 May 2012 23:09:21 +0200 | Subject | Re: kernel BUG and freeze on cat /proc/tty/driver/serial | From | Zdenek Kabelac <> |
| |
2011/9/2 Zdenek Kabelac <zdenek.kabelac@gmail.com>: > 2011/3/10 Chuck Ebbert <cebbert@redhat.com>: >> On Wed, 16 Feb 2011 17:17:28 +0100 >> "Mario 'BitKoenig' Holbe" <Mario.Holbe@TU-Ilmenau.DE> wrote: >> >>> reading /proc/tty/driver/serial leads to a NULL pointer dereference >>> BUG and freeze on a serial-console enabled 2.6.35.{4,10,11} and >>> 2.6.37. 2.6.32.28 does fine without BUG and freeze. >>> >>> Fresh boot 2.6.35.11 into emergency... >>> # cat /proc/tty/driver/serial >>> [ 73.199568] BUG: unable to handle kernel NULL pointer dereference >>> at 00000099 [ 73.227373] IP: [<c11a8969>] tty_ldisc_try+0x10/0x35 >> >> The oops is here, in uart_handle_dcd_change() in serial_core.h: >> >> struct tty_ldisc *ld = tty_ldisc_ref(port->tty); >> >> (port->tty is NULL) >> >> Called from check_modem_status() in 8250.c: >> >> if (status & UART_MSR_DDCD) >> uart_handle_dcd_change(&up->port, status & UART_MSR_DCD); >> >> So apparently the port has no tty, until you run "setserial -g", or else >> that somehow makes the DCD status appear unchanged later when reading >> /proc/tty/driver/serial. > > > Just noticed the same freeze of my box with 3.1.0-rc4 - thought with > just a little bit different stack trace > (as I've taken only camera snap - here is just list of function) - > happened right after resume. > > tty_ldisc_try NULL pointer dereference > > tty_ldisc_ref > check_modem_status > serial8250_get_mctrl > uart_proc_show > ? seq_read > ? kmem_cache_alloc_trace > ? seq_read > seq_read > ? sub_preempt_count > ? seq_lseek > proc_reg_read > vfs_read > sys_read > system_call_fastpath
Anything new about this issue ?
Seems I'm getting recently several of those reports with 3.4 kernel:
tty_ldisc_ref uart_handle_dcd_change
Even something simple like this:
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 9c4c05b..32c68c0 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2453,7 +2453,7 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status) { struct uart_state *state = uport->state; struct tty_port *port = &state->port; - struct tty_ldisc *ld = tty_ldisc_ref(port->tty); + struct tty_ldisc *ld = port ? tty_ldisc_ref(port->tty) : NULL; struct pps_event_time ts;
if (ld && ld->ops->dcd_change) @@ -2465,7 +2465,7 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status) hardpps(); #endif
- if (port->flags & ASYNC_CHECK_CD) { + if (port && port->flags & ASYNC_CHECK_CD) { if (status) wake_up_interruptible(&port->open_wait); else if (port->tty)
Zdenek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |