From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1163161AbdDWSh2 (ORCPT <rfc822;w@1wt.eu>);
        Sun, 23 Apr 2017 14:37:28 -0400
Received: from mail-wm0-f67.google.com ([74.125.82.67]:32996 "EHLO
        mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1754677AbdDWShS (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Sun, 23 Apr 2017 14:37:18 -0400
From: Nicolai Stange <nicstange@gmail.com>
To: kernel test robot <xiaolong.ye@intel.com>
Cc: Nicolai Stange <nicstange@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Johannes Berg <johannes@sipsolutions.net>,
        "Paul E.McKenney" <paulmck@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, lkp@01.org
Subject: Re: [lkp-robot] [debugfs]  f3e7155d08: BUG:unable_to_handle_kernel
References: <20170418022358.GD1143@yexl-desktop>
Date: Sun, 23 Apr 2017 20:37:14 +0200
In-Reply-To: <20170418022358.GD1143@yexl-desktop> (kernel test robot's message
        of "Tue, 18 Apr 2017 10:23:58 +0800")
Message-ID: <871ssj3r8l.fsf@gmail.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v3NIbXlM023465

Hi Xiaolong,

I'm encountering some difficulties running the reproducer, see below.
Any help is very welcome!


On Tue, Apr 18 2017, kernel test robot wrote:

> [   45.772683] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
<snip>
> [   45.772697] IP: __debugfs_remove+0x5c/0xc0
> [   45.772743] Call Trace:
> [   45.772750]  debugfs_remove_recursive+0xd4/0x1e0
> [   45.772758]  rpc_clnt_debugfs_unregister+0x19/0x30
> [   45.772762]  rpc_client_register+0x18a/0x1c0
> [   45.772765]  rpc_new_client+0x1de/0x2e0
> [   45.772768]  rpc_create_xprt+0x58/0x170
> [   45.772769]  rpc_create+0xea/0x1c0
> [   45.772776]  nfs_create_rpc_client+0xe8/0x130
> [   45.772814]  nfs4_init_client+0x7e/0x290 [nfsv4]
> [   45.772820]  ? __radix_tree_replace+0x8a/0x140
> [   45.772823]  ? radix_tree_iter_tag_clear+0x1c/0x20
> [   45.772827]  ? __rpc_init_priority_wait_queue+0x81/0xb0
> [   45.772830]  ? rpc_init_wait_queue+0x13/0x20
> [   45.772847]  ? nfs4_alloc_client+0x1d2/0x1e0 [nfsv4]
<snip>
> [ 45.772985] Code: 8b 7c 24 30 48 89 de e8 f3 28 e6 ff 48 89 df e8 3b
> 22 e5 ff 4c 8b 63 78 48 c7 c2 20 d7 3b 82 48 c7 c6 e0 9f c9 81 49 8d
> 7c 24 18 <41> c7 44 24 10 00 00 00 00 4d 8d 6c 24 10 e8 a1 b6 cc ff 49
> 8d

Ok, that's

	41 c7 44 24 10 00 00 	movl   $0x0,0x10(%r12)

which is probably the init_completion() in __debugfs_remove_file():

	fsd = dentry->d_fsdata;
	init_completion(&fsd->active_users_drained);

This would mean that fsd == NULL and this can happen only if the dentry
in question isn't a regular file but a symlink or whatever. So, an
additional d_is_reg() is needed here. I'll fix this in the next
iteration once I got the reproducer working.


> To reproduce:
>
>         git clone https://github.com/01org/lkp-tests.git
>         cd lkp-tests
>         bin/lkp qemu -k <bzImage> job-script  # job-script is attached in this email
>

This gives

  make: Entering directory '/home/nic/lkp-tests/bin/event'
  gcc    -c -o wakeup.o wakeup.c
  gcc   -o wakeup wakeup.o
  rm -f wakeup.o
  strip wakeup
  make: Leaving directory '/home/nic/lkp-tests/bin/event'
  cpio: root:lkp: invalid group
  cpio: root:lkp: invalid group
  cpio: root:lkp: invalid group
  gzip: /home/nic/.lkp/cache/lkp-x86_64.cpio: No such file or directory
  mv: cannot stat ‘/home/nic/.lkp/cache/lkp-x86_64.cpio.gz’: No such file or directory
  mv: cannot stat ‘/home/nic/.lkp/cache/lkp-x86_64.cgz’: No such file or directory
  result_root: /home/nic/.lkp//result/boot/1/vm-lkp-nex04-8G/debian-x86_64-2016-08-31.cgz/x86_64-rhel-7.2/gcc-6/f3e7155d085591ab58f0993ce633fea58c082b35/3
  downloading initrds ...
  /usr/bin/wget -q --local-encoding=UTF-8 --retry-connrefused --waitretry 1000 --tries 1000 https://github.com/0day-ci/lkp-qemu/raw/master/osimage/debian/debian-x86_64-2016-08-31.cgz -N -P /home/nic/.lkp/cache/osimage/debian
  /usr/bin/wget -q --local-encoding=UTF-8 --retry-connrefused --waitretry 1000 --tries 1000 https://github.com/0day-ci/lkp-qemu/raw/master/osimage/deps/debian-x86_64-2016-08-31.cgz/lkp_2017-04-01.cgz -N -P /home/nic/.lkp/cache/osimage/deps/debian-x86_64-2016-08-31.cgz
  Failed to download osimage/deps/debian-x86_64-2016-08-31.cgz/lkp_2017-04-01.cgz

Manual download of that very last lkp_2017-04-01.cgz file results in a 404
error. Please let me know if you need more details.


Thank you!

Nicolai

From mboxrd@z Thu Jan  1 00:00:00 1970
Content-Type: multipart/mixed; boundary="===============6617984969303826728=="
MIME-Version: 1.0
From: Nicolai Stange <nicstange@gmail.com>
To: lkp@lists.01.org
Subject: Re: [lkp-robot] [debugfs] f3e7155d08: BUG:unable_to_handle_kernel
Date: Sun, 23 Apr 2017 20:37:14 +0200
Message-ID: <871ssj3r8l.fsf@gmail.com>
In-Reply-To: <20170418022358.GD1143@yexl-desktop>
List-Id: <oe-lkp.lists.linux.dev>

--===============6617984969303826728==
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable

Hi Xiaolong,

I'm encountering some difficulties running the reproducer, see below.
Any help is very welcome!


On Tue, Apr 18 2017, kernel test robot wrote:

> [   45.772683] BUG: unable to handle kernel NULL pointer dereference at 0=
000000000000010
<snip>
> [   45.772697] IP: __debugfs_remove+0x5c/0xc0
> [   45.772743] Call Trace:
> [   45.772750]  debugfs_remove_recursive+0xd4/0x1e0
> [   45.772758]  rpc_clnt_debugfs_unregister+0x19/0x30
> [   45.772762]  rpc_client_register+0x18a/0x1c0
> [   45.772765]  rpc_new_client+0x1de/0x2e0
> [   45.772768]  rpc_create_xprt+0x58/0x170
> [   45.772769]  rpc_create+0xea/0x1c0
> [   45.772776]  nfs_create_rpc_client+0xe8/0x130
> [   45.772814]  nfs4_init_client+0x7e/0x290 [nfsv4]
> [   45.772820]  ? __radix_tree_replace+0x8a/0x140
> [   45.772823]  ? radix_tree_iter_tag_clear+0x1c/0x20
> [   45.772827]  ? __rpc_init_priority_wait_queue+0x81/0xb0
> [   45.772830]  ? rpc_init_wait_queue+0x13/0x20
> [   45.772847]  ? nfs4_alloc_client+0x1d2/0x1e0 [nfsv4]
<snip>
> [ 45.772985] Code: 8b 7c 24 30 48 89 de e8 f3 28 e6 ff 48 89 df e8 3b
> 22 e5 ff 4c 8b 63 78 48 c7 c2 20 d7 3b 82 48 c7 c6 e0 9f c9 81 49 8d
> 7c 24 18 <41> c7 44 24 10 00 00 00 00 4d 8d 6c 24 10 e8 a1 b6 cc ff 49
> 8d

Ok, that's

	41 c7 44 24 10 00 00 	movl   $0x0,0x10(%r12)

which is probably the init_completion() in __debugfs_remove_file():

	fsd =3D dentry->d_fsdata;
	init_completion(&fsd->active_users_drained);

This would mean that fsd =3D=3D NULL and this can happen only if the dentry
in question isn't a regular file but a symlink or whatever. So, an
additional d_is_reg() is needed here. I'll fix this in the next
iteration once I got the reproducer working.


> To reproduce:
>
>         git clone https://github.com/01org/lkp-tests.git
>         cd lkp-tests
>         bin/lkp qemu -k <bzImage> job-script  # job-script is attached in=
 this email
>

This gives

  make: Entering directory '/home/nic/lkp-tests/bin/event'
  gcc    -c -o wakeup.o wakeup.c
  gcc   -o wakeup wakeup.o
  rm -f wakeup.o
  strip wakeup
  make: Leaving directory '/home/nic/lkp-tests/bin/event'
  cpio: root:lkp: invalid group
  cpio: root:lkp: invalid group
  cpio: root:lkp: invalid group
  gzip: /home/nic/.lkp/cache/lkp-x86_64.cpio: No such file or directory
  mv: cannot stat =E2=80=98/home/nic/.lkp/cache/lkp-x86_64.cpio.gz=E2=80=99=
: No such file or directory
  mv: cannot stat =E2=80=98/home/nic/.lkp/cache/lkp-x86_64.cgz=E2=80=99: No=
 such file or directory
  result_root: /home/nic/.lkp//result/boot/1/vm-lkp-nex04-8G/debian-x86_64-=
2016-08-31.cgz/x86_64-rhel-7.2/gcc-6/f3e7155d085591ab58f0993ce633fea58c082b=
35/3
  downloading initrds ...
  /usr/bin/wget -q --local-encoding=3DUTF-8 --retry-connrefused --waitretry=
 1000 --tries 1000 https://github.com/0day-ci/lkp-qemu/raw/master/osimage/d=
ebian/debian-x86_64-2016-08-31.cgz -N -P /home/nic/.lkp/cache/osimage/debian
  /usr/bin/wget -q --local-encoding=3DUTF-8 --retry-connrefused --waitretry=
 1000 --tries 1000 https://github.com/0day-ci/lkp-qemu/raw/master/osimage/d=
eps/debian-x86_64-2016-08-31.cgz/lkp_2017-04-01.cgz -N -P /home/nic/.lkp/ca=
che/osimage/deps/debian-x86_64-2016-08-31.cgz
  Failed to download osimage/deps/debian-x86_64-2016-08-31.cgz/lkp_2017-04-=
01.cgz

Manual download of that very last lkp_2017-04-01.cgz file results in a 404
error. Please let me know if you need more details.


Thank you!

Nicolai

--===============6617984969303826728==--