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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 BA1C5C5B57A for ; Sat, 29 Jun 2019 18:21:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9721F21726 for ; Sat, 29 Jun 2019 18:21:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amarulasolutions.com header.i=@amarulasolutions.com header.b="Vc8I/IQc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726864AbfF2SVl (ORCPT ); Sat, 29 Jun 2019 14:21:41 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:36900 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726873AbfF2SVk (ORCPT ); Sat, 29 Jun 2019 14:21:40 -0400 Received: by mail-wr1-f67.google.com with SMTP id v14so9506944wrr.4 for ; Sat, 29 Jun 2019 11:21:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amarulasolutions.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=cOuGUeuvXYYHOBYHD3qLjLapejxLIFLy8lgJ6YZYaC8=; b=Vc8I/IQcDMsgrM97xjkT289KsEWPVOydDdA3LMxpz53y7k7on8Qe6YP6x5a7Q7s7DQ fq8sn95P7OsHdMkHO37MR3IxrqSRdBOqPAdW2nM+YOzEVSewvtbtfvntUb9b9D6nyUKi 4+mPOafSRzFlPvK9UGLi71zUDQPc+q+jXNjlg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=cOuGUeuvXYYHOBYHD3qLjLapejxLIFLy8lgJ6YZYaC8=; b=CYI0kyVFoesmYklQZXCorThOqS1tc7w2Dt1yRfkflzic6Y55lQtJAMtM06pQhTrlTx n0/x6GdPSVvfAg8XQrjGnUD2DJbkgivX8jCXOMi5EOohaMzgW5bVq1Vfr2ds4f4hfgUY yiaSsdSY3MRPjYd+triXGL22CqgNLWB4sD6aFClUkSvPT/ptSv+3LJhfYHTn3XFFlBt6 jWWIqpKqmTb6gtH+lgyao/j6nBIv2FURowdcQRdQ9c7lBpXDXckkoucP4Dhjo+FDPip+ Koachc7VX9TSw8HJkv5hSxijFqNzYPPEiLbVTsRsMI5DzTcnMRveDnbv1IDYwxK/bO/s 3ncw== X-Gm-Message-State: APjAAAULh2BNVmvX08FvFojiXXK3q04v/W7RCmGaqUEUZ7BvYAP0euxc KeFVKvR5PUWTOvD0hx1Skog8Jw== X-Google-Smtp-Source: APXvYqyDOqRN53A/pUdk7Ix1TM1I+/1F4ot46+1LL5m576jRJeOlLgdjBFxQpToalRTFnuuvM3wY0w== X-Received: by 2002:adf:e384:: with SMTP id e4mr2439057wrm.308.1561832498351; Sat, 29 Jun 2019 11:21:38 -0700 (PDT) Received: from andrea ([93.90.167.233]) by smtp.gmail.com with ESMTPSA id h84sm6945311wmf.43.2019.06.29.11.21.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 29 Jun 2019 11:21:37 -0700 (PDT) Date: Sat, 29 Jun 2019 20:21:32 +0200 From: Andrea Parri To: "Paul E. McKenney" Cc: Steven Rostedt , Byungchul Park , Scott Wood , Joel Fernandes , Sebastian Andrzej Siewior , rcu , LKML , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan Subject: Re: [RFC] Deadlock via recursive wakeup via RCU with threadirqs Message-ID: <20190629182132.GA5666@andrea> References: <20190627181638.GA209455@google.com> <20190627184107.GA26519@linux.ibm.com> <13761fee4b71cc004ad0d6709875ce917ff28fce.camel@redhat.com> <20190627203612.GD26519@linux.ibm.com> <20190628073138.GB13650@X58A-UD3R> <20190628104045.GA8394@X58A-UD3R> <20190628114411.5d9ab351@gandalf.local.home> <20190629151236.GA7862@andrea> <20190629165533.GA3112@linux.ibm.com> <20190629180910.GA3399@andrea> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190629180910.GA3399@andrea> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org > Remark: we do have code which (while acknowledging that "interrupts are > synchronization points") doesn't quite seem to "believe it", c.f., e.g., > kernel/sched/membarrier.c:ipi_mb(). So, I guess the follow-up question > would be "Would we better be (more) paranoid? ..." should have been "IPIs are serializing" (so all a different "order"...) Andrea