From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751862AbeDFP7K (ORCPT ); Fri, 6 Apr 2018 11:59:10 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:36607 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751027AbeDFP7I (ORCPT ); Fri, 6 Apr 2018 11:59:08 -0400 X-Google-Smtp-Source: AIpwx49YIdnNfgYYmAjKK7B2thpMWN32ZOJWc+QvXC4nX4m0ihOoc23k3WiBsgcvbHa3uuAnjaZ61g== Date: Fri, 6 Apr 2018 08:59:05 -0700 From: Omar Sandoval To: Peter Zijlstra Cc: Tetsuo Handa , viro@zeniv.linux.org.uk, osandov@fb.com, dvyukov@google.com, bot+abdba5bc6de135d7622f00756da97998425b6de5@syzkaller.appspotmail.com, axboe@kernel.dk, tom.leiming@gmail.com, hare@suse.de, shli@fb.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, mingo@redhat.com, linux-fsdevel@vger.kernel.org, knikanth@suse.de Subject: Re: INFO: task hung in lo_ioctl Message-ID: <20180406155905.GA11697@vader> References: <94eb2c0810d04f5a46055ffc71aa@google.com> <6012a726-069a-13a5-9c8d-6a11730d8414@I-love.SAKURA.ne.jp> <468f7418-a02d-79cc-3d94-91bbe146567e@I-love.SAKURA.ne.jp> <20180406121411.GJ4082@hirez.programming.kicks-ass.net> <201804062255.HEJ82361.FJOFHVtSLOMOQF@I-love.SAKURA.ne.jp> <20180406154343.GK4082@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180406154343.GK4082@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 06, 2018 at 05:43:43PM +0200, Peter Zijlstra wrote: > On Fri, Apr 06, 2018 at 10:55:03PM +0900, Tetsuo Handa wrote: > > Peter Zijlstra wrote: > > > On Fri, Apr 06, 2018 at 09:04:18PM +0900, Tetsuo Handa wrote: > > > > + /* Temporary hack for handling lock imbalance. */ > > > > + if (__mutex_owner(&lo->lo_ctl_mutex) == current) > > > > + mutex_unlock(&lo->lo_ctl_mutex); > > > > > > ARGGH.. you didn't read the comment we put on that? > > > > > > > Commit 5b52330bbfe63b33 ("audit: fix auditd/kernel connection state tracking") > > is using __mutex_owner(). ;-) > > That got removed and the warning added. Seems easy enough to fix without resorting to __mutex_owner() (untested): diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 264abaaff662..cee258d12a1e 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1300,12 +1300,13 @@ loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { static int loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { struct loop_info64 info64; - int err = 0; + int err; - if (!arg) - err = -EINVAL; - if (!err) - err = loop_get_status(lo, &info64); + if (!arg) { + mutex_unlock(&lo->lo_ctl_mutex); + return -EINVAL; + } + err = loop_get_status(lo, &info64); if (!err && copy_to_user(arg, &info64, sizeof(info64))) err = -EFAULT; I'll test it and send it up when I get into the office.