From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751409AbdB1R6H (ORCPT ); Tue, 28 Feb 2017 12:58:07 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:33186 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751037AbdB1R6E (ORCPT ); Tue, 28 Feb 2017 12:58:04 -0500 Date: Tue, 28 Feb 2017 09:57:25 -0800 From: Guenter Roeck To: Tobias Klauser Cc: Sven Schmidt <4sschmid@informatik.uni-hamburg.de>, Arnd Bergmann , Andrew Morton , linux-kernel@vger.kernel.org, Ley Foon Tan , nios2-dev@lists.rocketboards.org, Sandra Loosemore Subject: Re: nios2 crash/hang in mainline due to 'lib: update LZ4 compressor module' Message-ID: <20170228175725.GB13455@roeck-us.net> References: <20170226210338.GA19476@roeck-us.net> <20170228155331.GC27998@distanz.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170228155331.GC27998@distanz.ch> User-Agent: Mutt/1.5.24 (2015-08-30) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: guenter@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 28, 2017 at 04:53:31PM +0100, Tobias Klauser wrote: > (adding Sandra Loosemore to Cc due to possible relation to gcc/binutils > for nios2) > > On 2017-02-26 at 22:03:38 +0100, Guenter Roeck wrote: > > Hi Sven, > > > > my qemu test for nios2 started failing with commit 4e1a33b105dd ("lib: > > update LZ4 compressor module"). The test hangs early during boot before > > any console output is seen. Reverting the offending patch as well as the > > subsequent lz4 related patches fixes the problem. Disabling CONFIG_RD_LZ4 > > and with it other LZ4 options also fixes it (as does adding "return -EINVAL;" > > at the top of the LZ4 decompression code). For reference, bisect log > > is attached. > > > > I tried with buildroot toolchains using gcc 6.1.0 as well as 6.3.0 > > and binutils 2.26.1. Scripts used to run the tests are available at > > https://github.com/groeck/linux-build-test/tree/master/rootfs/nios2. > > Qemu is from qemu mainline or qemu v2.8 with nios2 patches applied. > > Looks like this is somehow related to gcc/binutils. Using GCC 4.8.3 and > binutils 2.24.51 (both from from Sourcery CodeBench Lite 2014.05) I can > get a kernel booting on latest master branch. AFAICT, none of the > LZ4_decompress_* functions are called during boot. > > However, using a self-built GCC 7.0 (20161127) and binutils 2.27 I can > reproduce the problem you see using the instructions Guenter provided in > the reply to Sven. > > I'll try to dig a bit deeper from here on. Any suggestions on what to > look out for wrt the differences between the gcc/binutils version are > welcome of course. > I tried the following combinations of gcc and binutils: gcc 6.1.0; binutils 2.26.1 gcc 6.3.0; binutils 2.25.1 gcc 6.3.0; binutils 2.26.1 gcc 6.3.0; binutils 2.27 I used buildroot 2017.02-rc3 to build the toolchains. All have the problem. Another data point, confirming what you say above: I am relatively (99%) sure that the code in question is not actually called. I added reference counters to make sure that this is the case. Just the existence of the LZ4 decompression code appears to be sufficient to cause the boot failure. Weird. I just hope this only affects nios2. Guenter