From owner-svn-src-head@freebsd.org Sun Feb 5 21:06:59 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 1F3B4CD24EB; Sun, 5 Feb 2017 21:06:59 +0000 (UTC) (envelope-from andreast@FreeBSD.org) Received: from smtp.imp.ch (smtp.imp.ch [IPv6:2001:4060:1:1001::13:197]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id C7D211DF8; Sun, 5 Feb 2017 21:06:58 +0000 (UTC) (envelope-from andreast@FreeBSD.org) Received: from [192.168.225.14] (dhclient-91-190-14-19.flashcable.ch [91.190.14.19]) (using TLSv1 with cipher ECDHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by fgznet.ch (Postfix) with ESMTPSA id 7FC1F10D06A; Sun, 5 Feb 2017 22:06:46 +0100 (CET) Subject: Re: svn commit: r313037 - in head/sys: amd64/include kern mips/include net powerpc/include sparc64/include To: Jason Harmening , Svatopluk Kraus References: <201702010332.v113WnYf041362@repo.freebsd.org> <20170203231238.0675c289@kan> <8523aaa5-6c30-9f9f-40f0-fdf82cdf1669@pix.net> <6bf86e46-9714-c7e9-8d47-845761e2de24@FreeBSD.org> <8a2f7f7d-14c3-8e75-e060-fc41213ce389@FreeBSD.org> Cc: Kurt Lidl , Alexander Kabaev , "Jason A. Harmening" , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org, Ed Maste , Justin Hibbits From: Andreas Tobler Message-ID: Date: Sun, 5 Feb 2017 22:06:46 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: Obelix Submit on 127.0.1.1 X-Mailman-Approved-At: Mon, 06 Feb 2017 01:19:06 +0000 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 Feb 2017 21:06:59 -0000 On 05.02.17 19:59, Jason Harmening wrote: > Actually attaching the patch this time (**** gmail client) > > On Sun, Feb 5, 2017 at 10:58 AM, Jason Harmening > > wrote: > > Hmm, it's a good idea to consider the possibility of a barrier > issue. It wouldn't be the first time we've had such a problem on a > weakly-ordered architecture. That said, I don't see a problem in > this case. smp_rendezvous_cpus() takes a spinlock and then issues > atomic_store_rel_int() to ensure the rendezvous params are visible > to other cpus. The latter corresponds to lwsync on powerpc, which > AFAIK should be sufficient to ensure visibility of prior stores. > > For now I'm going with the simpler explanation that I made a bad > assumption in the powerpc get_pcpu() and there is some context in > which the read of sprg0 doesn't return a consistent pointer value. > Unfortunately I don't see where that might be right now. > > On the mips side, Kurt/Alexander can you test the attached patch? > It contains a simple fix to ensure get_pcpu() returns the consistent > per-cpu pointer. Here the panic I received with the latest patch you sent. World & kernel are on 313286 + patch. https://people.freebsd.org/~andreast/pcpu/ It is the same panic, pic 2 is with a try to get a core .... The load issue was a gmake -j8 bootstrap of todays gcc trunk sources. The machine has 2 physical CPU's, two threads pre cpu :) I revert now and see if the situation becomes stable again or if there is something else. Andreas