From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: 4.3 serial driver crashes with console shortly after boot Date: Mon, 9 Nov 2015 20:52:41 -0500 Message-ID: <56414DE9.20707@hurleysoftware.com> References: <20151110002939.GG3533@two.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20151110002939.GG3533@two.firstfloor.org> Sender: linux-kernel-owner@vger.kernel.org To: Andi Kleen Cc: gregkh@linuxfoundation.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-serial@vger.kernel.org Hi Andi, On 11/09/2015 07:29 PM, Andi Kleen wrote: > > Hi, > > With 4.3 an x86 server is always crashing roughly a minute after boot > in __uart_start/uart_tx_stopped. This is repeatable over multiple boots. Sorry about that. There was a similar report about this with 4.2 which I thought was fixed by: commit e144c58cad6667876173dd76977e9e6557e34941 Author: Peter Hurley Date: Sun Jul 12 21:05:26 2015 -0400 serial: core: Fix crashes while echoing when closing > The back trace is > flush_to_ldisc->n_tty_receive_buf2->n_tty_receive_buf_common-> > commit_echoes-> uart_flush_chars->uart_start > > It seems to follow a bad pointer here > > ffffffff813bbdfa: f6 80 f4 01 00 00 01 testb $0x1,0x1f4(%rax) > <--- > ffffffff813bbe01: 74 01 je ffffffff813bbe04 > <__uart_start.isra.1+0x24> > > Unfortunately I don't have the contents of RAX which scrolled away, > but since CR2 is 1f4 I suspect it's NUL. > > It seems to depend on the order of the console=... arguments on the > kernel command line. With console=tty0 console=ttyS0,115200n8 it > crashes, but when reversing the options it does not crash. I've just tried to reproduce this without success on my current tree which has some additional patches I just posted this am. They weren't intended to fix crashes but they directly impact the area of concern. Could you try these three? [PATCH v2 2/4] n_tty: Ignore all read data when closing [PATCH v2 3/4] tty: Abstract and encapsulate tty->closing behavior [PATCH v2 4/4] tty: Remove drivers' extra tty_ldisc_flush() links to those patches https://lkml.org/lkml/2015/11/9/260 https://lkml.org/lkml/2015/11/9/259 https://lkml.org/lkml/2015/11/9/261 Regards, Peter Hurley