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[209.132.180.67]) by mx.google.com with ESMTP id s24-v6si9436873plq.358.2018.07.23.13.35.00; Mon, 23 Jul 2018 13:35:14 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388183AbeGWVhE (ORCPT + 99 others); Mon, 23 Jul 2018 17:37:04 -0400 Received: from smtp1.it.da.ut.ee ([193.40.5.66]:57270 "EHLO smtp1.it.da.ut.ee" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388022AbeGWVhE (ORCPT ); Mon, 23 Jul 2018 17:37:04 -0400 Received: from math.ut.ee (unknown [IPv6:2001:bb8:2002:2400:5054:ff:fe3b:8db9]) by smtp1.it.da.ut.ee (Postfix) with ESMTP id 7478D206E2; Mon, 23 Jul 2018 23:34:07 +0300 (EEST) Received: by math.ut.ee (Postfix, from userid 1014) id 61C7E22091E; Mon, 23 Jul 2018 23:34:05 +0300 (EEST) Received: from localhost (localhost [127.0.0.1]) by math.ut.ee (Postfix) with ESMTP id 68B8F220905; Mon, 23 Jul 2018 23:34:05 +0300 (EEST) Date: Mon, 23 Jul 2018 23:34:05 +0300 (EEST) From: Meelis Roos To: Daniel Borkmann cc: Arnd Bergmann , Linux Kernel list , Networking Subject: Re: bisected: 4.18-rc* regression: x86-32 troubles (with timers?) In-Reply-To: <32227088-7754-c160-8046-e860f42ca91c@iogearbox.net> Message-ID: References: <32227088-7754-c160-8046-e860f42ca91c@iogearbox.net> User-Agent: Alpine 2.21 (LRH 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > >> 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? 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). -- Meelis Roos (mroos@linux.ee)