From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751226AbdIOHJl (ORCPT ); Fri, 15 Sep 2017 03:09:41 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:44956 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750820AbdIOHJk (ORCPT ); Fri, 15 Sep 2017 03:09:40 -0400 Date: Fri, 15 Sep 2017 09:09:27 +0200 (CEST) From: Thomas Gleixner To: Andy Lutomirski cc: LKML , Linus Torvalds , X86 ML Subject: Re: BUG: Sporadic crashes with current Linus tree In-Reply-To: Message-ID: References: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 14 Sep 2017, Andy Lutomirski wrote: > On Thu, Sep 14, 2017 at 9:00 AM, Thomas Gleixner wrote: > > On Thu, 14 Sep 2017, Andy Lutomirski wrote: > >> On Thu, Sep 14, 2017 at 12:38 AM, Thomas Gleixner wrote: > >> > Hi! > >> > > >> > I've seen the following crash sporadically with commit 46c1e79fee: > >> > > >> > Have not seen that with 3882a734c19b, though I saw the PCID warnings on > >> > that machine. > >> > > >> > I have no idea how to reproduce so bisecting is pretty much pointless. Any > >> > idea what to do? > >> > >> Does tools/testing/selftests/x86/sigreturn_64 reproduce it? > > > > Will try tomorrow once I figured out how to compile that stuff. Invoking a > > simple make in that directory fails. > > What's the error? It works for me. gcc -m64 -o /home/tglx/work/kernel/linus/linux/tools/testing/selftests/x86/sysret_ss_attrs_64 -O2 -g -std=gnu99 -pthread -Wall sysret_ss_attrs.c thunks.S -lrt -ldl /usr/bin/ld: /tmp/cco4vSkU.o: relocation R_X86_64_32S against `.text' can not be used when making a shared object; recompile with -fPIC /usr/bin/ld: final link failed: Nonrepresentable section on output collect2: error: ld returned 1 exit status > > > > Built it manually and when I run it tells: stack16 is too high > > > >> Ugh, weird. It kind of looks like current->thread.sp0 == NULL. I > >> have a patch series that changes a bunch of that code in my git tree, > >> but that's definitely not in Linus' tree. > > > > Right. The stupid thing is that the machine did not throw up all day > > neither idle nor loaded. Still the same kernel which barfed tonight several > > times. > > This is weird. The crashing process is rsyslogd, which should have > been running for a long time and shouldn't have any strange state. I > wonder if this is some kind of memory corruption. There would have to > be corruption of thread_struct *and* some kind of issue causing IRET > to fail, though. > > The attached patch could plausibly give some useful hint. I'll put it on that machine and hope it will reproduce. Didn't die since yesterday moring .... Thanks, tglx