From owner-freebsd-current@FreeBSD.ORG Wed Aug 5 07:03:56 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 57B64106566B; Wed, 5 Aug 2009 07:03:56 +0000 (UTC) (envelope-from nparhar@gmail.com) Received: from mail-pz0-f174.google.com (mail-pz0-f174.google.com [209.85.222.174]) by mx1.freebsd.org (Postfix) with ESMTP id 17BCD8FC08; Wed, 5 Aug 2009 07:03:55 +0000 (UTC) (envelope-from nparhar@gmail.com) Received: by pzk4 with SMTP id 4so3648664pzk.7 for ; Wed, 05 Aug 2009 00:03:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:date:from:to:cc:subject :message-id:mail-followup-to:references:mime-version:content-type :content-disposition:in-reply-to:user-agent; bh=1/P6K6usCjP5++B08o05k+FVoqZk7rwZ15xsPLUw97E=; b=XvwKYvtAHQQgMGh47w79bSWXFvGtESOUOTBkXMcBe89gAew/pI9gcwetAwtr303Evr mJoenXojC5CYVrKyaUbRB0UD177agfiuqbtaMDIiGaD+Zq2BSfS5NjbAzqoxRAUkNgvC fGCCELwxQ3L1KGmGFQ47qq99z/9hqJ0T0f0uo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; b=dF1xLzG1uOo18BYfvjUVHsks5s+07Oi0PJX4XS4/rH2bt6IFKwEqT9ab3KvMJ8I9dk 8VHCrynTQbi0xhPM5qMGy+XNW3HQbYXaUrg3w1KZy5tI+YUyfzRhA0Tairk7FdSihomF w82Bu89lHu6V3n+sNyN4s3f8MOfV6kwIdSpqk= Received: by 10.114.125.13 with SMTP id x13mr9865596wac.122.1249454062618; Tue, 04 Aug 2009 23:34:22 -0700 (PDT) Received: from doormat.home (c-76-126-210-244.hsd1.ca.comcast.net [76.126.210.244]) by mx.google.com with ESMTPS id l30sm12750886waf.0.2009.08.04.23.34.20 (version=TLSv1/SSLv3 cipher=RC4-MD5); Tue, 04 Aug 2009 23:34:21 -0700 (PDT) Date: Tue, 4 Aug 2009 23:34:17 -0700 From: Navdeep Parhar To: "Bjoern A. Zeeb" Message-ID: <20090805063417.GA10969@doormat.home> Mail-Followup-To: "Bjoern A. Zeeb" , Navdeep Parhar , freebsd-current@freebsd.org References: <20090804225806.GA54680@hub.freebsd.org> <20090805054115.O93661@maildrop.int.zabbadoz.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090805054115.O93661@maildrop.int.zabbadoz.net> User-Agent: Mutt/1.5.20 (2009-06-14) Cc: freebsd-current@freebsd.org, Navdeep Parhar Subject: Re: reproducible panic in netisr X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Aug 2009 07:03:56 -0000 On Wed, Aug 05, 2009 at 05:43:17AM +0000, Bjoern A. Zeeb wrote: > On Tue, 4 Aug 2009, Navdeep Parhar wrote: > > Hi, > > >This occurs on today's HEAD + some unrelated patches. That makes it > >8.0BETA2+ code. I haven't tried older builds. > > We have finally been able to reproduce this ourselves yesterday and Well, it happens every single time on all of my amd64 machines. After I'd already sent my email I noticed that the netisr mutex has an odd address (pun intended :-)) m=0xffffffff8144d867 It's a bit unusual for the mutex struct to start at a completely unaligned address. I hope things are better on sparc64 etc., not everyone is as forgiving as amd64. The mutex led me to some DPCPU stuff that I didn't quite get. (kgdb) p/x dpcpu_off $2 = {0x8407d7, 0xffffff807f4037d7, 0x0 } (kgdb) p dpcpu $3 = (void *) 0xffffff8000010000 (kgdb) p &__start_set_pcpu $4 = (uintptr_t **) 0xffffffff80c0c829 (kgdb) p/x 0xffffff8000010000 - 0xffffffff80c0c829 $5 = 0xffffff807f4037d7 It's not clear why we prefer to store offsets from DPCPU_START, instead of the base address of the dpcpu area directly. On amd64, the dpcpu area for cpu 0 is above kernbase (immediately after kernbase + thread0's stack). For the other CPUs it's below kernbase. This makes the pointer arithmetic that calculates offsets more "interesting." Why have a dpcpu_off[] instead of a dpcpu_base[]? > I might have a patch that I need to discuss with the relevant parties > first, to confirm that it's correct before circulating another bug as > patchh, as well as confirm some things with objdump. I should be able to test it. As I mentioned I get a page fault everytime I run NPtcp -h localhost. Regards, Navdeep > > /bz > > -- > Bjoern A. Zeeb The greatest risk is not taking one. > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org"