From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3067ECDE5F for ; Mon, 23 Jul 2018 22:04:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 84BE420852 for ; Mon, 23 Jul 2018 22:04:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 84BE420852 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=iogearbox.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388184AbeGWXHu (ORCPT ); Mon, 23 Jul 2018 19:07:50 -0400 Received: from www62.your-server.de ([213.133.104.62]:34137 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388139AbeGWXHu (ORCPT ); Mon, 23 Jul 2018 19:07:50 -0400 Received: from [78.46.172.2] (helo=sslproxy05.your-server.de) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.85_2) (envelope-from ) id 1fhiwR-00051Z-Fy; Tue, 24 Jul 2018 00:04:31 +0200 Received: from [99.0.85.34] (helo=localhost.localdomain) by sslproxy05.your-server.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1fhiwR-000DFE-1r; Tue, 24 Jul 2018 00:04:31 +0200 Subject: Re: bisected: 4.18-rc* regression: x86-32 troubles (with timers?) To: Meelis Roos Cc: Arnd Bergmann , Linux Kernel list , Networking References: <32227088-7754-c160-8046-e860f42ca91c@iogearbox.net> From: Daniel Borkmann Message-ID: <4a48811d-4094-ee4c-33ca-2cf0446a6313@iogearbox.net> Date: Tue, 24 Jul 2018 00:04:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.100.0/24776/Mon Jul 23 18:44:17 2018) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/23/2018 10:34 PM, Meelis Roos wrote: >>>> Now this seems more relevant: >>>> >>>> mroos@rx100s2:~/linux$ nice git bisect good >>>> 24dea04767e6e5175f4750770281b0c17ac6a2fb is the first bad commit >>>> commit 24dea04767e6e5175f4750770281b0c17ac6a2fb >>>> Author: Daniel Borkmann >>>> Date: Fri May 4 01:08:23 2018 +0200 >>>> >>>> bpf, x32: remove ld_abs/ld_ind >>>> >>>> Since LD_ABS/LD_IND instructions are now removed from the core and >>>> reimplemented through a combination of inlined BPF instructions and >>>> a slow-path helper, we can get rid of the complexity from x32 JIT. >>> >>> This does seem much more likely than the previous bisection, given >>> that you ended up in an x86-32 specific commit (the subject says x32, >>> but that is a mistake). I also checked that systemd indeed does >>> call into bpf in a number of places, possibly for the journald socket. >>> >>> OTOH, it's still hard to tell how that commit can have ended up >>> corrupting the clock read function in systemd. To cross-check, >>> could you try reverting that commit on the latest kernel and see >>> if it still works? >> >> I would be curious as well about that whether revert would make it >> work. What's the value of sysctl net.core.bpf_jit_enable ? Does it >> change anything if you set it to 0 (only interpreter) or 1 (JIT >> enabled). Seems a bit strange to me that bisect ended at this commit >> given the issue you have. The JIT itself was also new in this window >> fwiw. In any case some more debug info would be great to have. > > net.core.bpf_jit_enable is 1. > > Since it breaks bootup, I can not easily change the value at runtime (it > would be postfactum). Do you mean changing the > CONFIG_BPF_JIT_ALWAYS_ON=y option? Yeah if you chance it to N, and don't have any fixed /etc/sysctl.conf setting, then you'll boot up with interpreter first (net.core.bpf_jit_enable as 0). Curious whether that works just fine for you. > Anyway, I started compile of v4.18-rc5 that was the latest I tested, > with the commit in question reverted. Will see if I can test tomorrow > morning. But I will leave tomorrow for a week and can only test further > things if they happen to boot fine (no manual reboot possible for a > week). Ok, thanks, please keep us posted on the outcome with the revert. Right now I would doubt it's related resp. changes anything on the issue, but lets see. Thanks, Daniel