From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752942AbZHTITK (ORCPT ); Thu, 20 Aug 2009 04:19:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752501AbZHTITJ (ORCPT ); Thu, 20 Aug 2009 04:19:09 -0400 Received: from mail-ew0-f207.google.com ([209.85.219.207]:61586 "EHLO mail-ew0-f207.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752385AbZHTITI convert rfc822-to-8bit (ORCPT ); Thu, 20 Aug 2009 04:19:08 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=mlqkbiBGTBFP/2LoYO6DfxVOlCrSdxYF/+/wk4EmGioojcyQlRtpAXge40xJwGpp15 5ToCydygY832+T4XsKD904Q/SPJngbv44SN5vamEZHMk9SGxOkRE1ylJsO1zhKPjZJbW A7FQK2xKF1tSddWGVFWMz0bsrBM6ElD40rbS0= MIME-Version: 1.0 In-Reply-To: References: Date: Thu, 20 Aug 2009 16:19:08 +0800 Message-ID: Subject: Re: v2.6.31-rc6: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 From: Dave Young To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Linus Torvalds , Alan Cox , Greg Kroah-Hartman Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 20, 2009 at 4:00 PM, Eric W. Biederman wrote: > Dave Young writes: > >> On Thu, Aug 20, 2009 at 2:07 PM, Eric W. Biederman wrote: >>> >>> ebiederm@xmission.com (Eric W. Biederman) writes: >>> >>>> I'm not certain who I should route this too, but I just had 2.6.31-rc6 >>>> fall over on me.  I don't know how reproducible this will be but >>>> I have a full crash dump if someone is interested in looking into this. >>> >>> Looks like I was wrong.  This is appears trivial to reproduce, >>> I have just reproduced it two more times in a row.  I think >>> the problem is pty related. >>> >>> I was looking into a change in behavior on 2.6.31-rc6 where >>> data was being lost, and it appears one variant of my test program >>> kills the kernel. >>> >>> The following program run as an unprivileged user causes a kernel >>> panic in about a minute: >>> >>> aka >>> >>> while :; do ./KernelTtyTest ; done >> >> The test app failed for me: >> >> read failed: Input/output error >> lastbytes: '\r\nprocess_cmd read failed: Interrupted system >> call\r\necho _2_\r\n' >> Aborted > > > Oh.  It definitely fails.  I just found that when it failed > about 600 times in a row it took my kernel with it.  I was > developing it to understand tty interactions, and when I realized > that the version I had was killing my kernel I sent it out > as it was a nice self contained test case. Confirm: I can reproduce on i386 machine. > > Eric > -- Regards dave