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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 9DBA8C76190 for ; Fri, 26 Jul 2019 00:00:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 70EB2229F9 for ; Fri, 26 Jul 2019 00:00:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726952AbfGZAAl (ORCPT ); Thu, 25 Jul 2019 20:00:41 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:57606 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726380AbfGZAAl (ORCPT ); Thu, 25 Jul 2019 20:00:41 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92 #3 (Red Hat Linux)) id 1hqney-0004fd-VN; Fri, 26 Jul 2019 00:00:33 +0000 Date: Fri, 26 Jul 2019 01:00:32 +0100 From: Al Viro To: Linus Torvalds Cc: Cyril Hrubis , kernel test robot , LKP , LKML , ltp@lists.linux.it Subject: Re: [LTP] 56cbb429d9: ltp.fs_fill.fail Message-ID: <20190726000032.GK1131@ZenIV.linux.org.uk> References: <20190725110944.GA22106@shao2-debian> <20190725132617.GA23135@rei.lan> <20190725180428.GH1131@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190725180428.GH1131@ZenIV.linux.org.uk> User-Agent: Mutt/1.12.0 (2019-05-25) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 25, 2019 at 07:04:28PM +0100, Al Viro wrote: > On Thu, Jul 25, 2019 at 09:32:13AM -0700, Linus Torvalds wrote: > > On Thu, Jul 25, 2019 at 6:26 AM Cyril Hrubis wrote: > > > > > > This looks like mkfs.vfat got EBUSY after the loop device was > > > succesfully umounted. > > > > Hmm. Smells like the RCU-delaying got triggered again. > > > > We have that "synchronize_rcu_expedited()" in namespace_unlock(), > > which is so that everything should be done by the time we return to > > user space. > > > > Al, maybe that RCU synchronization should be after the mntput()s? > > There are several interesting issues in there, but synchronize_rcu() > should be between zeroing ->mnt_ns and dropping the final refs. > I'm digging through that crap right now; at least one bug is dealt > with by #fixes, but there's more, unfortunately. No, it's not synchronize_rcu(). It's a bug dealt with in vfs.git #fixes, triggering the struct mount leak in mount_subtree(), which is used by btrfs. Immediately prior to vfat in their list... (oh, and AFAICS "more" in the above had been a mismerge in -next, so it might really be all there is to it) Folks, see if vfs.git #fixes solves that one. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Date: Fri, 26 Jul 2019 01:00:32 +0100 Subject: [LTP] 56cbb429d9: ltp.fs_fill.fail In-Reply-To: <20190725180428.GH1131@ZenIV.linux.org.uk> References: <20190725110944.GA22106@shao2-debian> <20190725132617.GA23135@rei.lan> <20190725180428.GH1131@ZenIV.linux.org.uk> Message-ID: <20190726000032.GK1131@ZenIV.linux.org.uk> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ltp@lists.linux.it On Thu, Jul 25, 2019 at 07:04:28PM +0100, Al Viro wrote: > On Thu, Jul 25, 2019 at 09:32:13AM -0700, Linus Torvalds wrote: > > On Thu, Jul 25, 2019 at 6:26 AM Cyril Hrubis wrote: > > > > > > This looks like mkfs.vfat got EBUSY after the loop device was > > > succesfully umounted. > > > > Hmm. Smells like the RCU-delaying got triggered again. > > > > We have that "synchronize_rcu_expedited()" in namespace_unlock(), > > which is so that everything should be done by the time we return to > > user space. > > > > Al, maybe that RCU synchronization should be after the mntput()s? > > There are several interesting issues in there, but synchronize_rcu() > should be between zeroing ->mnt_ns and dropping the final refs. > I'm digging through that crap right now; at least one bug is dealt > with by #fixes, but there's more, unfortunately. No, it's not synchronize_rcu(). It's a bug dealt with in vfs.git #fixes, triggering the struct mount leak in mount_subtree(), which is used by btrfs. Immediately prior to vfat in their list... (oh, and AFAICS "more" in the above had been a mismerge in -next, so it might really be all there is to it) Folks, see if vfs.git #fixes solves that one. From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============3182150825679624323==" MIME-Version: 1.0 From: Al Viro To: lkp@lists.01.org Subject: Re: [LTP] 56cbb429d9: ltp.fs_fill.fail Date: Fri, 26 Jul 2019 01:00:32 +0100 Message-ID: <20190726000032.GK1131@ZenIV.linux.org.uk> In-Reply-To: <20190725180428.GH1131@ZenIV.linux.org.uk> List-Id: --===============3182150825679624323== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Thu, Jul 25, 2019 at 07:04:28PM +0100, Al Viro wrote: > On Thu, Jul 25, 2019 at 09:32:13AM -0700, Linus Torvalds wrote: > > On Thu, Jul 25, 2019 at 6:26 AM Cyril Hrubis wrote: > > > > > > This looks like mkfs.vfat got EBUSY after the loop device was > > > succesfully umounted. > > = > > Hmm. Smells like the RCU-delaying got triggered again. > > = > > We have that "synchronize_rcu_expedited()" in namespace_unlock(), > > which is so that everything should be done by the time we return to > > user space. > > = > > Al, maybe that RCU synchronization should be after the mntput()s? > = > There are several interesting issues in there, but synchronize_rcu() > should be between zeroing ->mnt_ns and dropping the final refs. > I'm digging through that crap right now; at least one bug is dealt > with by #fixes, but there's more, unfortunately. No, it's not synchronize_rcu(). It's a bug dealt with in vfs.git #fixes, triggering the struct mount leak in mount_subtree(), which is used by btrfs. Immediately prior to vfat in their list... (oh, and AFAICS "more" in the above had been a mismerge in -next, so it might really be all there is to it) Folks, see if vfs.git #fixes solves that one. --===============3182150825679624323==--