From: Chuck Ebbert <cebbert@redhat.com>
To: "Mario 'BitKoenig' Holbe" <Mario.Holbe@TU-Ilmenau.DE>
Cc: linux-kernel@vger.kernel.org
Subject: Re: kernel BUG and freeze on cat /proc/tty/driver/serial
Date: Thu, 10 Mar 2011 01:49:52 -0500 [thread overview]
Message-ID: <20110310014952.38b7a6ef@redhat.com> (raw)
In-Reply-To: <20110216161728.GA8431@darkside.kls.lan>
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.
next prev parent reply other threads:[~2011-03-10 6:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-16 16:17 kernel BUG and freeze on cat /proc/tty/driver/serial Mario 'BitKoenig' Holbe
2011-03-08 16:10 ` Mario 'BitKoenig' Holbe
2011-03-10 6:49 ` Chuck Ebbert [this message]
2011-09-02 18:23 ` Zdenek Kabelac
2012-05-24 21:09 ` Zdenek Kabelac
2012-05-24 23:09 ` Alan Cox
2012-05-25 8:23 ` Zdenek Kabelac
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