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=-5.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 88508C2D0E4 for ; Tue, 24 Nov 2020 20:34:45 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EFB922068D for ; Tue, 24 Nov 2020 20:34:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="QJf2L5tE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EFB922068D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TfW5RXoopPEmQr4kIB5EB/YYm2TbCxu3lhuAZwt6kWo=; b=QJf2L5tE17Htrq+7djfjLMAcM Q9feICOE/5d6pem8YjtaD8owGCaW4EnfVyF18L841L54YbzLnXOrLElDmnEQlFXy2VM1eSlOXhjT8 lequsLY5zgah5dEvNHl14MHY2jk1qlx7nIE8R9rKig7S40KpG24J5ZMu/GHbPD0ZAPX0QeISASaz1 qjpBtb//eysODiym3XKASivTxymuQ0AkRyEwayR7LLRYffXp8N1DCrbK0J71R35zg51g8JAcGJDK0 y8XjTH7otyCxXw8qLYMi+BYb6ic0ibbsb48sBazh5SO4OXgo19/9JroDVy3vxdVeQI3t6qHsuF+Zd fN7URzJLw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1khezg-00060Y-4J; Tue, 24 Nov 2020 20:32:56 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1khezd-0005zR-8c for linux-arm-kernel@lists.infradead.org; Tue, 24 Nov 2020 20:32:54 +0000 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C409620678; Tue, 24 Nov 2020 20:32:47 +0000 (UTC) Date: Tue, 24 Nov 2020 15:32:45 -0500 From: Steven Rostedt To: Mark Rutland Subject: Re: linux-next: stall warnings and deadlock on Arm64 (was: [PATCH] kfence: Avoid stalling...) Message-ID: <20201124153245.5bda420d@oasis.local.home> In-Reply-To: <20201124194308.GC8957@C02TD0UTHF1T.local> References: <20201119170259.GA2134472@elver.google.com> <20201119184854.GY1437@paulmck-ThinkPad-P72> <20201119193819.GA2601289@elver.google.com> <20201119213512.GB1437@paulmck-ThinkPad-P72> <20201119225352.GA5251@willie-the-truck> <20201120103031.GB2328@C02TD0UTHF1T.local> <20201120140332.GA3120165@elver.google.com> <20201123193241.GA45639@C02TD0UTHF1T.local> <20201124140310.GA811510@elver.google.com> <20201124150146.GH1437@paulmck-ThinkPad-P72> <20201124194308.GC8957@C02TD0UTHF1T.local> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201124_153253_404202_97D8CC3D X-CRM114-Status: GOOD ( 14.12 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marco Elver , Anders Roxell , "Paul E. McKenney" , Jann Horn , Peter Zijlstra , boqun.feng@gmail.com, Lai Jiangshan , Linux Kernel Mailing List , kasan-dev , rcu@vger.kernel.org, Linux-MM , Alexander Potapenko , linux-arm-kernel@lists.infradead.org, Tejun Heo , Andrew Morton , Will Deacon , tglx@linutronix.de, Dmitry Vyukov Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 24 Nov 2020 19:43:08 +0000 Mark Rutland wrote: > AFAICT, the issue is that arch_cpu_idle() can be dynamically traced with > ftrace, and hence the tracing code can unexpectedly run without RCU > watching. Since that's dynamic tracing, we can avoid it by marking > arch_cpu_idle() and friends as noinstr. Technically, ftrace doesn't care if RCU is watching or not, but the callbacks might, and they need to do the rcu_is_watching() check if they do. Although, there's work to keep those areas from being traced, but to do so, they really need to be minimal, where you don't ever want to trace them. -- Steve _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel