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[209.132.180.67]) by mx.google.com with ESMTP id t130si4307782oih.37.2019.12.05.04.08.22; Thu, 05 Dec 2019 04:08:36 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=sq8wL7AJ; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729329AbfLEMGg (ORCPT + 99 others); Thu, 5 Dec 2019 07:06:36 -0500 Received: from mail-qt1-f194.google.com ([209.85.160.194]:40425 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729187AbfLEMGg (ORCPT ); Thu, 5 Dec 2019 07:06:36 -0500 Received: by mail-qt1-f194.google.com with SMTP id z22so3279812qto.7 for ; Thu, 05 Dec 2019 04:06:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=F6zHO/WCNUOJMFt0div43uU4YpgZXs8QE00GO2bNAOk=; b=sq8wL7AJ/+Mo4kdKlEjtVjVm2c/Kq/drIwY4aK59mtehKOQFqbYhnfUPP9a9T7XBP5 llKuSWKB+Iq09BIfDEE11CvsUde33Jst5tMP8UjZglnByVypwtPnrJv1w2U0ZNjKQfqe he5q107St5f2RZEigfpMn9FVtBSs3ngX9ps9lxSUlm9UJIP26lR3KpAiuNHAW8nVBe4V xLsa2kAC9b9QL4MV/UKcoCnjOOkTKuTah7l5yb6oGU0YMIRRg+Bq6DnZxp28wHkcIEHs jwGCrvjtZU7fUDOXvNu25Tlw59oh9pgV/LwiUB73yMCksXnBt1P8O7shPafOjczJxJ4s Fefg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=F6zHO/WCNUOJMFt0div43uU4YpgZXs8QE00GO2bNAOk=; b=bGz9TWsdHSwYGiQxMk30tqfgUZ8rnXcRFAGtIuXGjzOr4246tO4BAgyKwG+VdCoaA8 RIXdqJggZAYg2aDZE8uI7e4Ej54Ydr5qc6ULFNKCatAYMR6IjiwuY4iXpnOaIHJUEmRc Q3AkQvn8MQ5Rpef5NbmWAYbfMzCBJOmbW5YS/loQ1Gg+B+cAmhWULUbs2J9MQgHpysfO gpM4ikXDYKyfU9ye34DnkexrKfDtbx6cWzVIos0mt9Tv6fo8vWUVyqOCdZCqxVg1I39G W85q5E3wBFTdsZ487KVVpVO4p80o9iTtRcikzuOIQ/tVJ9QTBOw/6aDaZKv3kx9LUI37 RNKg== X-Gm-Message-State: APjAAAXC8GDKwLfIg3zj+Owsw9Y1lvO2akFkxZXHUyhPBe+MJBWRePhP 5R/e9sO8ri9P1wQjnMTud2E3D1xiE1cx1ZxSxhsr/g== X-Received: by 2002:ac8:2489:: with SMTP id s9mr7142276qts.257.1575547594783; Thu, 05 Dec 2019 04:06:34 -0800 (PST) MIME-Version: 1.0 References: <00000000000096009b056df92dc1@google.com> <20191205100047.GA11438@Johanness-MacBook-Pro.local> <20191205113838.GC11438@Johanness-MacBook-Pro.local> <20191205115033.GJ2734@suse.cz> In-Reply-To: <20191205115033.GJ2734@suse.cz> From: Dmitry Vyukov Date: Thu, 5 Dec 2019 13:06:23 +0100 Message-ID: Subject: Re: kernel BUG at fs/btrfs/volumes.c:LINE! To: dsterba@suse.cz, Johannes Thumshirn , Dmitry Vyukov , Johannes Thumshirn , syzbot , Chris Mason , dsterba@suse.com, linux-btrfs@vger.kernel.org, LKML , syzkaller-bugs Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 5, 2019 at 12:50 PM David Sterba wrote: > > On Thu, Dec 05, 2019 at 12:38:38PM +0100, Johannes Thumshirn wrote: > > On Thu, Dec 05, 2019 at 11:07:27AM +0100, Dmitry Vyukov wrote: > > > The correct syntax would be (no dash + colon): > > > > > > #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/jth/linux.git > > > close_fs_devices > > > > Ah ok, thanks. > > > > Although syzbot already said it can't test because it has no reproducer. > > Anyways good to know for future reports. > > According to > > https://syzkaller.appspot.com/bug?id=d50670eeb21302915bde3f25871dfb7ea43db1e4 > > there is a way how to test it, many reports and the last one about a > week old. Is there a way to instruct syzbot to run the same tests on a > given branch? > > (The reproducer is basically setting up environment with limited amount > of memory available for allocation and this hits the BUG_ON.) syzkaller does this ("rerun the same tests") for every bug always. If it succeeds (kernel crashes again), it results in a reproducer, that can later be used for cause/fix bisection and patch testing. In this case it does not reproduce, so rerunning the same tests will not lead to anything useful (only if to false confirmation that a patch fixes the crash). There is a large number of reasons why a kernel crash may not reproduce. It may be global accumulated state, non-hermetic tests, poor syzkaller btrfs descriptions (most likely true) and others. Need to take a closer look, on first sight it looks like something that should be reproduced...