From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034180AbdAEPS1 (ORCPT ); Thu, 5 Jan 2017 10:18:27 -0500 Received: from mx1.redhat.com ([209.132.183.28]:40022 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751306AbdAEPSU (ORCPT ); Thu, 5 Jan 2017 10:18:20 -0500 Date: Thu, 5 Jan 2017 09:17:00 -0600 From: Josh Poimboeuf To: Dmitry Vyukov Cc: syzkaller , Andrey Konovalov , Andrey Ryabinin , Alexander Potapenko , kasan-dev , "linux-mm@kvack.org" , LKML , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "x86@kernel.org" , Kostya Serebryany Subject: Re: x86: warning in unwind_get_return_address Message-ID: <20170105151700.4n7wpynvsv2yjotp@treble> References: <20161220210144.u47znzx6qniecuvv@treble> <20161220233640.pc4goscldmpkvtqa@treble> <20161222051701.soqwh47frxwsbkni@treble> <20170105144942.whqucdwmeqybng3s@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 05 Jan 2017 15:17:08 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 05, 2017 at 03:59:52PM +0100, Dmitry Vyukov wrote: > On Thu, Jan 5, 2017 at 3:49 PM, Josh Poimboeuf wrote: > > On Tue, Dec 27, 2016 at 05:38:59PM +0100, Dmitry Vyukov wrote: > >> On Thu, Dec 22, 2016 at 6:17 AM, Josh Poimboeuf wrote: > >> > On Wed, Dec 21, 2016 at 01:46:36PM +0100, Andrey Konovalov wrote: > >> >> On Wed, Dec 21, 2016 at 12:36 AM, Josh Poimboeuf wrote: > >> >> > > >> >> > Thanks. Looking at the stack trace, my guess is that an interrupt hit > >> >> > while running in generated BPF code, and the unwinder got confused > >> >> > because regs->ip points to the generated code. I may need to disable > >> >> > that warning until we figure out a better solution. > >> >> > > >> >> > Can you share your .config file? > >> >> > >> >> Sure, attached. > >> > > >> > Ok, I was able to recreate with your config. The culprit was generated > >> > code, as I suspected, though it wasn't BPF, it was a kprobe (created by > >> > dccpprobe_init()). > >> > > >> > I'll make a patch to disable the warning. > >> > >> Hi, > >> > >> I am also seeing the following warnings: > >> > >> [ 281.889259] WARNING: kernel stack regs at ffff8801c29a7ea8 in > >> syz-executor8:1302 has bad 'bp' value ffff8801c29a7f28 > >> [ 833.994878] WARNING: kernel stack regs at ffff8801c4e77ea8 in > >> syz-executor1:13094 has bad 'bp' value ffff8801c4e77f28 > >> > >> Can it also be caused by bpf/kprobe? > > > > This is a different warning. I suspect it's due to unwinding the stack > > of another CPU while it's running, which is still possible in a few > > places. I'm going to have to disable all these warnings for now. > > > I also have the following diff locally. These loads trigger episodic > KASAN warnings about stack-of-bounds reads on rcu stall warnings when > it does backtrace of all cpus. > If it looks correct to you, can you please also incorporate it into your patch? Ok, will do. BTW, I think there's an issue with your mail client. Your last two replies to me didn't have me on To/Cc. -- Josh