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=1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FSL_HELO_FAKE,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH,USER_AGENT_MUTT 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 BA092C4321A for ; Mon, 10 Jun 2019 18:30:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 98ADC2085A for ; Mon, 10 Jun 2019 18:30:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560191439; bh=ohK4n4b1EpBzFuYCAPxK1UhSnRZ6JiT2DsSBhq0Kuec=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=IRGznDWgt5d5wLLwkbdRa1V4/ebNRfyLYK/6wtEdFpzXCwIJ3az9Hut3ycHk/2mdW CdYgl7C6f5JRrWT9xXqUFfLf9MMq6cfn398KdlT6FsE+Mr9Ie9GiL8ngYx423G74MJ fenEavS6bfXvQ6gEuqjHCx+gG428pmrslTjGzlzY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387994AbfFJSaf (ORCPT ); Mon, 10 Jun 2019 14:30:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:34906 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387425AbfFJSae (ORCPT ); Mon, 10 Jun 2019 14:30:34 -0400 Received: from gmail.com (unknown [104.132.1.77]) (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 0570D2082E; Mon, 10 Jun 2019 18:30:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560191434; bh=ohK4n4b1EpBzFuYCAPxK1UhSnRZ6JiT2DsSBhq0Kuec=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jV6eylv2gneDFF28UAnW0Bl5g/y+cDC7sNrwqd9k01Zh3l57SQM9oA2oeMbq3B4Ue qmByOcsZd7IJiV9Tp4/RTv2yrB7z7NnJwLFAswEvrKqfhD/3AwnWkJx/09oR1eEwkY 7NJ1Its8t1y+v+W2XHpMTyIIQRQ52ngBiyqb4Kdg= Date: Mon, 10 Jun 2019 11:30:32 -0700 From: Eric Biggers To: David Howells , Al Viro Cc: Mark Rutland , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: "Dentry still in use" splats in v5.2-rc3 Message-ID: <20190610183031.GE63833@gmail.com> References: <20190605135401.GB30925@lakrids.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190605135401.GB30925@lakrids.cambridge.arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Jun 05, 2019 at 02:54:01PM +0100, Mark Rutland wrote: > Hi All, > > While fuzzing arm64 v5.2-rc3, Syzkaller started hitting splats of the > form: > > BUG: Dentry (____ptrval____){i=1,n=/} still in use (2) [unmount of bpf bpf] > > ... which I can reliably reproduce with the following C program > (partially minimized from what Syzkaller auto-generated). > > It looks like any filesystem will do. I've seen splats with "bpf", > "hugetlbfs", "rpc_pipefs", and "tmpfs", and can reproduce the problem > with any of these. > > Any ideas? > > I'm using the config from my fuzzing/5.2-rc3 branch on kernel.org [1]. > > Thanks, > Mark. > > ---- > #include > #include > > /* > * NOTE: these are the arm64 numbers > */ > #ifndef __NR_fsconfig > #define __NR_fsconfig 431 > #endif > #ifndef __NR_fsmount > #define __NR_fsmount 432 > #endif > #ifndef __NR_fsopen > #define __NR_fsopen 430 > #endif > > int main(void) > { > int fs, mnt; > > fs = syscall(__NR_fsopen, "bpf", 0); > syscall(__NR_fsconfig, fs, 6, 0, 0, 0); > mnt = syscall(__NR_fsmount, fs, 0, 0); > fchdir(mnt); > > close(fs); > close(mnt); > } > David and Al, is sys_fsmount() missing a call to mntget()? - Eric