Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757400AbcK2Mnh (ORCPT ); Tue, 29 Nov 2016 07:43:37 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:38393 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755684AbcK2Mn3 (ORCPT ); Tue, 29 Nov 2016 07:43:29 -0500 Date: Tue, 29 Nov 2016 13:43:23 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: "Paul E. McKenney" , Vince Weaver , "linux-kernel@vger.kernel.org" , Ingo Molnar , Arnaldo Carvalho de Melo , "dvyukov@google.com" Subject: Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Message-ID: <20161129124323.GJ3092@twins.programming.kicks-ass.net> References: <20161128215411.fkis7bbimjy4v4j7@treble> <20161129004021.GL3924@linux.vnet.ibm.com> <20161129055241.6dy2dt4q4ptazk2s@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161129055241.6dy2dt4q4ptazk2s@treble> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 826 Lines: 20 On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > Did a little digging on git blame and found the following commit (which > seems to be the cause of the KASAN warning and missing stack dump): > > bc1dce514e9b ("rcu: Don't use NMIs to dump other CPUs' stacks") > > I presume this commit is still needed because of the NMI printk deadlock > issues which were discussed at Kernel Summit. I guess those issues need > to be sorted out before the above commit can be reverted. Also, I most always run with these here patches applied: https://lkml.kernel.org/r/20161018170830.405990950@infradead.org People are very busy polishing the turd we call printk, but from where I'm sitting its terminally and unfixably broken. I should certainly add a revert of the above commit to the stack of patches I carry.