linux-kernel - Re: mm/sched/net: BUG when running simple code

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Message-ID: <20140613032754.GA20729@gmail.com>
Date:	Fri, 13 Jun 2014 06:27:54 +0300
From:	Dan Aloni <dan@...nelim.com>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Dave Jones <davej@...hat.com>
Subject: Re: mm/sched/net: BUG when running simple code

On Thu, Jun 12, 2014 at 10:56:16PM -0400, Sasha Levin wrote:
> Hi all,
> 
> Okay, I'm really lost. I got the following when fuzzing, and can't really explain what's
> going on. It seems that we get a "unable to handle kernel paging request" when running
> rather simple code, and I can't figure out how it would cause it.
[..]
> Which agrees with the trace I got:
> 
> [  516.309720] BUG: unable to handle kernel paging request at ffffffffa0f12560
> [  516.309720] IP: netlink_getsockopt (net/netlink/af_netlink.c:2271)
[..]
> [  516.309720] RIP netlink_getsockopt (net/netlink/af_netlink.c:2271)
> [  516.309720]  RSP <ffff8803fc85fed8>
> [  516.309720] CR2: ffffffffa0f12560
> 
> They only theory I had so far is that netlink is a module, and has gone away while the code
> was executing, but netlink isn't a module on my kernel.

The RIP - 0xffffffffa0f12560 is in the range (from Documentation/x86/x86_64/mm.txt):

    ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space

So seems it was in a module.

-- 
Dan Aloni
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