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=-2.1 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 52EEFC76192 for ; Mon, 15 Jul 2019 13:29:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C0A42081C for ; Mon, 15 Jul 2019 13:29:26 +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="k1xsuzrc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730227AbfGON3V (ORCPT ); Mon, 15 Jul 2019 09:29:21 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:35942 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730134AbfGON3V (ORCPT ); Mon, 15 Jul 2019 09:29:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=r9X1nghjzop7IMmkkwDPTymZ4Xv+LpVt5mTtmfKekm0=; b=k1xsuzrcvlM122V0VW+E05XLJ Hm/L5W6LUxvgcgX6TcmXyGijEZNpEM/3PgekuPyDDle5gwFPy//job23ju2uNdle250U9ifNCoO1B p7XI2084yU9OgvD7hpefvV2oiiRp4U5P4YhWaZzZ3Tr6RhLKlT5FnorNsfHw+4UxKWHqSlpSJZ+mv QHNd8mKPcXCjbOZ+0MPWwLZZcCQohwYm7tIYGyLqF6G2dSuu6WbPUfmxRRRw75Fsfq+XiRn5Iz/i+ r+FoSfbmuOYq1TOAcuEe4d6WvrTfQHIFWNCEG7o4TKLh4JJqL9RqDzaGBtrw21BPU2UgzIs15i7Pr 97Adxeyiw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hn12X-0008Q5-3p; Mon, 15 Jul 2019 13:29:13 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 80E272013A7F2; Mon, 15 Jul 2019 15:29:11 +0200 (CEST) Date: Mon, 15 Jul 2019 15:29:11 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Dmitry Vyukov , Theodore Ts'o , syzbot , Andreas Dilger , David Miller , eladr@mellanox.com, Ido Schimmel , Jiri Pirko , John Stultz , linux-ext4@vger.kernel.org, LKML , netdev , syzkaller-bugs , Thomas Gleixner , Ingo Molnar Subject: Re: INFO: rcu detected stall in ext4_write_checks Message-ID: <20190715132911.GG3419@hirez.programming.kicks-ass.net> References: <20190705151658.GP26519@linux.ibm.com> <20190705191055.GT26519@linux.ibm.com> <20190706042801.GD11665@mit.edu> <20190706061631.GV26519@linux.ibm.com> <20190706150226.GG11665@mit.edu> <20190706180311.GW26519@linux.ibm.com> <20190707011655.GA22081@linux.ibm.com> <20190714184915.GK26519@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190714184915.GK26519@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Sun, Jul 14, 2019 at 11:49:15AM -0700, Paul E. McKenney wrote: > On Sun, Jul 14, 2019 at 05:48:00PM +0300, Dmitry Vyukov wrote: > > But short term I don't see any other solution than stop testing > > sched_setattr because it does not check arguments enough to prevent > > system misbehavior. Which is a pity because syzkaller has found some > > bad misconfigurations that were oversight on checking side. > > Any other suggestions? > > Keep the times down to a few seconds? Of course, that might also > fail to find interesting bugs. Right, if syzcaller can put a limit on the period/deadline parameters (and make sure to not write "-1" to /proc/sys/kernel/sched_rt_runtime_us) then per the in-kernel access-control should not allow these things to happen.