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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 4D772C4646D for ; Fri, 28 Jun 2019 13:55:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14C43208E3 for ; Fri, 28 Jun 2019 13:55:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="RIDEBwrI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726863AbfF1Nzb (ORCPT ); Fri, 28 Jun 2019 09:55:31 -0400 Received: from merlin.infradead.org ([205.233.59.134]:43412 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726686AbfF1Nz3 (ORCPT ); Fri, 28 Jun 2019 09:55:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=wYcNOsgWlh/Ecvl7SnDlME5ey9iGCA4wqtawTfBrfA4=; b=RIDEBwrIx6GsUKo+FjlwKVVjj 1P2Fr1cfIItpXAzZ+4UY5WxaxqmQ/o+Z+v/ydg9fsdVq/HkRs5lUvb/Jn9f9J1UbYaJjecj3lcqbm qkgmYhKsDCwxq9KUb0hM9Y3hIyNsBu5RZEhu7WIxoyeouCLclHYxcnTibmqFuabcFth3VkVDuvSAu 3HFy+O+sAvC/6C+qKv8RF61/hezoa2L4qM7/f2/1fF0KpNJnpxbdvqEGRRqvuYPTGLXBiYwBr73wy oBSVr66FtiU41RsooPhKpBhFddbWbY+WLoPhBtSpTveZVc12mMblXdLM/yhaLb003Ni6cA6NZEVSv sWXHf0JEA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hgrKm-0000rK-8L; Fri, 28 Jun 2019 13:54:36 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8C8642010DE3A; Fri, 28 Jun 2019 15:54:33 +0200 (CEST) Date: Fri, 28 Jun 2019 15:54:33 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Joel Fernandes , Steven Rostedt , Sebastian Andrzej Siewior , rcu , LKML , Thomas Gleixner , Ingo Molnar , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan Subject: Re: [RFC] Deadlock via recursive wakeup via RCU with threadirqs Message-ID: <20190628135433.GE3402@hirez.programming.kicks-ass.net> References: <20190626135447.y24mvfuid5fifwjc@linutronix.de> <20190626162558.GY26519@linux.ibm.com> <20190627142436.GD215968@google.com> <20190627103455.01014276@gandalf.local.home> <20190627153031.GA249127@google.com> <20190627155506.GU26519@linux.ibm.com> <20190627173831.GW26519@linux.ibm.com> <20190627181638.GA209455@google.com> <20190627184107.GA26519@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190627184107.GA26519@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 27, 2019 at 11:41:07AM -0700, Paul E. McKenney wrote: > Or just don't do the wakeup at all, if it comes to that. I don't know > of any way to determine whether rcu_read_unlock() is being called from > the scheduler, but it has been some time since I asked Peter Zijlstra > about that. There (still) is no 'in-scheduler' state.