linux-kernel - Re: BUG: unable to handle kernel paging request from pty

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Message-ID: <56D0109E.9070102@suse.cz>
Date:	Fri, 26 Feb 2016 09:45:18 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	stable <stable@...r.kernel.org>, lwn@....net,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: BUG: unable to handle kernel paging request from pty_write [was:
 Linux 4.4.2]

On 02/26/2016, 01:38 AM, Peter Hurley wrote:
>> That would imply that RSP was off by +8 when the ttwu_stat() epilog was
>> executed so that RBP <= ret addr and RIP <= some local var in try_to_wake_up()
>> stack frame.
>>
>> Looks like R15 in the crash report could be what RBP should have been.
>>
>> Now to find out why RSP is +8
> 
> Which I would investigate if I could download that kernel.
> Unfortunately, OBS doesn't like me so if you could make that
> kernel available some other way or send me a mixed listing
> of kernel/sched/core.c

Actually I cannot do mixed listing using objdump, as my objdump
complains in the middle of vmlinux:
objdump: Dwarf Error: mangled line number section.

and dumps no more code afterwards. (And core.c is after the error happens.)

Nevertheless, I did:
gdb vmlinux-4.4.2-3-default -ex 'disass /m try_to_wake_up' --batch >
try_to_wake_up.mixed
gdb vmlinux-4.4.2-3-default -ex 'disass /m ttwu_stat' --batch
>ttwu_stat.mixed

And both will appear at:
http://labs.suse.cz/jslaby/bug-968218/

thanks,
-- 
js
suse labs