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From: Andi Kleen <andi@firstfloor.org>
To: gregkh@linuxfoundation.org, linux-serial@vger.kernel.org,
	linux-kernel@vger.kernel.org, peter@hurleysoftware.com
Subject: 4.3 serial driver crashes with console shortly after boot
Date: Tue, 10 Nov 2015 01:29:39 +0100	[thread overview]
Message-ID: <20151110002939.GG3533@two.firstfloor.org> (raw)


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.

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.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only.

             reply	other threads:[~2015-11-10  0:29 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-10  0:29 Andi Kleen [this message]
2015-11-10  1:52 ` 4.3 serial driver crashes with console shortly after boot Peter Hurley
2015-11-10 22:39   ` Andi Kleen
2015-11-10 22:43     ` Andi Kleen
2015-11-10 23:15       ` Peter Hurley
2015-11-11 11:14         ` Peter Hurley
2015-11-11 16:50           ` Andi Kleen
2017-06-23 11:23             ` Jiri Slaby

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