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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 04282C4361B for ; Sat, 5 Dec 2020 23:48:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9CF723136 for ; Sat, 5 Dec 2020 23:48:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727253AbgLEXr5 (ORCPT ); Sat, 5 Dec 2020 18:47:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725966AbgLEXr4 (ORCPT ); Sat, 5 Dec 2020 18:47:56 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B59BDC0613CF; Sat, 5 Dec 2020 15:47:16 -0800 (PST) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1607212034; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cCD+MM2ELmrBKfWFSQdz97hYPn7ejqug1YoM2ZlKSVU=; b=VyPbPWrI1bxz1ctAMcXAteyGb/wjM2BQkNGgg26A8YU/N9ribTwowxtdSbsLnaHsYgPoGB Wo6d+5hBRxmaJMUtpgIrvoEfRVwdSjzy0N2kO9JetY/CjyizlnyR8dukzAd55+3VrU00ZM AVkdTrzoIlMF0DoLsFFWQDYr9UCD7eLkBZUYDyLdy38EervQy3MlCzP7Tg9wyUYMlochiO UPFQwel5WVfpY6oiwvi+xS9xsALi4LlD9BrWA2ZYj6WzzKkFbvPRZJMnb5pO5vhUtYEE7B bmg9qrK3uiJoJBay2+KSBNTM9gg7nKnax+4wqOp3zqIhvD5H5xckKVyKkafbgQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1607212034; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cCD+MM2ELmrBKfWFSQdz97hYPn7ejqug1YoM2ZlKSVU=; b=05aQoE1F9U/F18I37fUGznt/ZaaLvFTUNj0MvApH+5DQGoIvUTh4Mut1AjkJabBY6Pg91k ADR9Cy9L2HozUqBg== To: Marco Elver , Naresh Kamboju Cc: open list , kasan-dev , rcu@vger.kernel.org, lkft-triage@lists.linaro.org, Peter Zijlstra , "Paul E. McKenney" , Ingo Molnar , fweisbec@gmail.com, Arnd Bergmann Subject: Re: BUG: KCSAN: data-race in tick_nohz_next_event / tick_nohz_stop_tick In-Reply-To: <87wnxw86bv.fsf@nanos.tec.linutronix.de> References: <87wnxw86bv.fsf@nanos.tec.linutronix.de> Date: Sun, 06 Dec 2020 00:47:13 +0100 Message-ID: <87eek395oe.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 05 2020 at 19:18, Thomas Gleixner wrote: > On Fri, Dec 04 2020 at 20:53, Marco Elver wrote: > It might be useful to find the actual variable, data member or whatever > which is involved in the various reports and if there is a match then > the reports could be aggregated. The 3 patterns here are not even the > complete possible picture. > > So if you sum them up: 58 + 148 + 205 instances then their weight > becomes more significant as well. I just looked into the moderation queue and picked stuff which I'm familiar with from the subject line. There are quite some reports which have a different trigger scenario, but are all related to the same issue. https://syzkaller.appspot.com/bug?id=f5a5ed5b2b6c3e92bc1a9dadc934c44ee3ba4ec5 https://syzkaller.appspot.com/bug?id=36fc4ad4cac8b8fc8a40713f38818488faa9e9f4 are just variations of the same problem timer_base->running_timer being set to NULL without holding the base lock. Safe, but insanely hard to explain why :) Next: https://syzkaller.appspot.com/bug?id=e613fc2458de1c8a544738baf46286a99e8e7460 https://syzkaller.appspot.com/bug?id=55bc81ed3b2f620f64fa6209000f40ace4469bc0 https://syzkaller.appspot.com/bug?id=972894de81731fc8f62b8220e7cd5153d3e0d383 ..... That's just the ones which caught my eye and all are related to task->flags usage. There are tons more judging from the subject lines. So you really want to look at them as classes of problems and not as individual scenarios. Thanks, tglx