Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965080AbeAKRD5 (ORCPT + 1 other); Thu, 11 Jan 2018 12:03:57 -0500 Received: from merlin.infradead.org ([205.233.59.134]:40424 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932773AbeAKRD4 (ORCPT ); Thu, 11 Jan 2018 12:03:56 -0500 Date: Thu, 11 Jan 2018 18:03:47 +0100 From: Peter Zijlstra To: Vince Weaver Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Ingo Molnar , Arnaldo Carvalho de Melo , Thomas Gleixner Subject: Re: perf: perf_fuzzer quickly locks up on 4.15-rc7 Message-ID: <20180111170347.GG6176@hirez.programming.kicks-ass.net> References: <20180108173005.lkglqrixb2ota6g2@gmail.com> <20180109102507.GG6176@hirez.programming.kicks-ass.net> <20180109132602.GA2369@hirez.programming.kicks-ass.net> <20180111091353.GW6176@hirez.programming.kicks-ass.net> <20180111153845.GD6176@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Thu, Jan 11, 2018 at 11:58:24AM -0500, Vince Weaver wrote: > On Thu, 11 Jan 2018, Vince Weaver wrote: > > > On Thu, 11 Jan 2018, Peter Zijlstra wrote: > > > > > OK, I'm going to try fuzzing as a user with paranoid=0, and if that > > > doesn't help, I'm going to switch to linus' tree with my patches on. > > > > OK, I'm fuzzing on a core2 machine and it locks up too. > > > > It did give the following first (but it kept going for at least a minute > > after this oops before locking solid). > > This was missing the first few lines which made it to the serial log but > not the console: > > [ 823.919729] BUG: unable to handle kernel paging request at ffff88011a7a1000 > [ 823.926928] IP: 0x7fbda0042b3c > > I'm dumping vmlinux and can't find address 0x7fbda0042b3c at all. That's a user address.. > Should I be able to find it there? Or is KASLR/KPTI or similar stopping > me? Something is definitely funny, lemme try and make sense of this splat. > > Jan 11 11:38:57 core2 kernel: [ 823.930123] PGD 22ea067 P4D 22ea067 PUD 22ed067 PMD 11a520063 PTE 800000011a7a1063 > > Jan 11 11:38:57 core2 kernel: [ 823.938012] Oops: 0002 [#1] SMP PTI > > Jan 11 11:38:57 core2 kernel: [ 823.968898] CPU: 1 PID: 17688 Comm: perf_fuzzer Not tainted 4.15.0-rc7+ #211 > > Jan 11 11:38:57 core2 kernel: [ 823.976152] Hardware name: AOpen DE7000/nMCP7ALPx-DE R1.06 Oct.19.2012, BIOS 080015 10/19/2012 > > Jan 11 11:38:57 core2 kernel: [ 823.985259] RIP: 0033:0x7fbda0042b3c > > Jan 11 11:38:57 core2 kernel: [ 823.989002] RSP: 002b:00007ffed7fa46c8 EFLAGS: 00010246 > > Jan 11 11:38:57 core2 kernel: [ 823.994434] RAX: 000000000000462d RBX: 000000000000000c RCX: 00007fbda0042b3c > > Jan 11 11:38:57 core2 kernel: [ 824.001786] RDX: 0000000000000000 RSI: 00007ffed7fa46dc RDI: 000000000000462d > > Jan 11 11:38:57 core2 kernel: [ 824.009135] RBP: 00007ffed7fa46e0 R08: 00007fbda032e0e4 R09: 0000000000000000 > > Jan 11 11:38:57 core2 kernel: [ 824.016483] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401950 > > Jan 11 11:38:57 core2 kernel: [ 824.023832] R13: 00007ffed7fa6ae0 R14: 0000000000000000 R15: 0000000000000000 > > Jan 11 11:38:57 core2 kernel: [ 824.031198] FS: 00007fbda0540700(0000) GS:ffff88011fc80000(0000) knlGS:0000000000000000 > > Jan 11 11:38:57 core2 kernel: [ 824.039530] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > Jan 11 11:38:57 core2 kernel: [ 824.045477] CR2: ffff88011a7a1000 CR3: 000000011a998000 CR4: 00000000000407e0 > > Jan 11 11:38:57 core2 kernel: [ 824.052827] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > Jan 11 11:38:57 core2 kernel: [ 824.060176] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 > > Jan 11 11:38:57 core2 kernel: [ 824.072767] CR2: ffff88011a7a1000 > > Jan 11 11:38:57 core2 kernel: [ 824.076248] ---[ end trace 31d5336f74638197 ]-- > > >