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 236CFC433B4 for ; Mon, 12 Apr 2021 20:37:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E71F36134F for ; Mon, 12 Apr 2021 20:37:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240051AbhDLUhc (ORCPT ); Mon, 12 Apr 2021 16:37:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51206 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238066AbhDLUhb (ORCPT ); Mon, 12 Apr 2021 16:37:31 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD508C061574 for ; Mon, 12 Apr 2021 13:37:12 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1618259830; 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=oh48Rss2+itxZmRETAokmr334utlKN/vxMR52g/3xqU=; b=FOok4NcdvWPuwMkC7QNjW7gCkdGJrxH/eERSy3WMlxPl2RVfATdXpivveJ2nD4jbVQ/0+W XlcbspjB4iZhYHCQ5IKqxYySqWYsiMcEWJcIBq8WrL/NMCraJdy6sjQasjUNOI8RIr/zHj qRJFEfQcNYkNFlztoGJLnHqbkzOQ5NuExNTNaEKVM5TetVfjzPLVsi7pSNrjAwKcf4mQzP UcizBF+nd9f2AOzaeK0v8jLIlKlyd/LABLjN4RDWzxYdR/qxhG8z5Q8iq6ImUZrxkfsFCV zOkMGI3/aEL+ILd2FnUd2i5/XNWjss9gHVRzcZTWBLRltGVqI48gnkS8o7X0OQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1618259830; 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=oh48Rss2+itxZmRETAokmr334utlKN/vxMR52g/3xqU=; b=PJBnop+Js3BbdyHLqTiQXr7bP0c4LuYRQGYE6Y+FNZeWS422FxpVkwHcK75iexI0PGJiW3 6t1Ygezpp2FxVOCg== To: paulmck@kernel.org Cc: linux-kernel@vger.kernel.org, john.stultz@linaro.org, sboyd@kernel.org, corbet@lwn.net, Mark.Rutland@arm.com, maz@kernel.org, kernel-team@fb.com, neeraju@codeaurora.org, ak@linux.intel.com Subject: Re: [PATCH v7 clocksource 3/5] clocksource: Check per-CPU clock synchronization when marked unstable In-Reply-To: <20210412195722.GG4510@paulmck-ThinkPad-P17-Gen-1> References: <20210402224828.GA3683@paulmck-ThinkPad-P72> <20210402224906.3912-3-paulmck@kernel.org> <87blam4iqe.ffs@nanos.tec.linutronix.de> <20210411002020.GV4510@paulmck-ThinkPad-P17-Gen-1> <878s5p2jqv.ffs@nanos.tec.linutronix.de> <20210411164612.GZ4510@paulmck-ThinkPad-P17-Gen-1> <20210412042157.GA1889369@paulmck-ThinkPad-P17-Gen-1> <87k0p71whr.ffs@nanos.tec.linutronix.de> <20210412182049.GE4510@paulmck-ThinkPad-P17-Gen-1> <87y2dnz644.ffs@nanos.tec.linutronix.de> <20210412195722.GG4510@paulmck-ThinkPad-P17-Gen-1> Date: Mon, 12 Apr 2021 22:37:10 +0200 Message-ID: <87o8ejz1c9.ffs@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 Mon, Apr 12 2021 at 12:57, Paul E. McKenney wrote: > On Mon, Apr 12, 2021 at 08:54:03PM +0200, Thomas Gleixner wrote: >> > I will send a new series out later today, Pacific Time. >> >> Can you do me a favour and send it standalone and not as yet another >> reply to this existing thread maze. A trivial lore link to the previous >> version gives enough context. > > Will do! > > Of course, it turns out that lockdep also doesn't like waited-on > smp_call_function_single() invocations from timer handlers, > so I am currently looking at other options for dealing with that > potential use-after-free. I am starting to like the looks of "only set > CLOCK_SOURCE_VERIFY_PERCPU on statically allocated clocksource structures > and let KASAN enforce this restriction", but I have not quite given up > on making it more general. The simplest point is in the thread under the clocksource_mutex which prevents anything from vanishing under your feet. Thanks, tglx