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From: CAI Qian <caiqian@redhat.com>
To: tj <tj@kernel.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Dave Chinner <david@fromorbit.com>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>, Nick Piggin <npiggin@gmail.com>,
	linux-fsdevel@vger.kernel.org
Subject: Re: local DoS - systemd hang or timeout (WAS: Re: [RFC][CFT] splice_read reworked)
Date: Wed, 5 Oct 2016 10:09:39 -0400 (EDT)
Message-ID: <1238277728.610186.1475676579513.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20161004214219.GN4205@htj.duckdns.org>



----- Original Message -----
> From: "tj" <tj@kernel.org>
> To: "CAI Qian" <caiqian@redhat.com>
> Cc: "Al Viro" <viro@ZenIV.linux.org.uk>, "Linus Torvalds" <torvalds@linux-foundation.org>, "Dave Chinner"
> <david@fromorbit.com>, "linux-xfs" <linux-xfs@vger.kernel.org>, "Jens Axboe" <axboe@kernel.dk>, "Nick Piggin"
> <npiggin@gmail.com>, linux-fsdevel@vger.kernel.org
> Sent: Tuesday, October 4, 2016 5:42:19 PM
> Subject: Re: local DoS - systemd hang or timeout (WAS: Re: [RFC][CFT] splice_read reworked)
> 
> Hello, CAI.
> 
> On Tue, Oct 04, 2016 at 01:39:11PM -0400, CAI Qian wrote:
> ...
> > Not sure if related, but right after this lockdep happened and trinity
> > running by a
> > non-privileged user finished inside the container. The host's systemctl
> > command just
> > hang or timeout which renders the whole system unusable.
> > 
> > # systemctl status docker
> > Failed to get properties: Connection timed out
> > 
> > # systemctl reboot (hang)
> > 
> ...
> > [ 5535.893675] INFO: lockdep is turned off.
> > [ 5535.898085] INFO: task kworker/45:4:146035 blocked for more than 120
> > seconds.
> > [ 5535.906059]       Tainted: G        W       4.8.0-rc8-fornext+ #1
> > [ 5535.912865] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables
> > this message.
> > [ 5535.921613] kworker/45:4    D ffff880853e9b950 14048 146035      2
> > 0x00000080
> > [ 5535.929630] Workqueue: cgroup_destroy css_killed_work_fn
> > [ 5535.935582]  ffff880853e9b950 0000000000000000 0000000000000000
> > ffff88086c6da000
> > [ 5535.943882]  ffff88086c9e2000 ffff880853e9c000 ffff880853e9baa0
> > ffff88086c9e2000
> > [ 5535.952205]  ffff880853e9ba98 0000000000000001 ffff880853e9b968
> > ffffffff817cdaaf
> > [ 5535.960522] Call Trace:
> > [ 5535.963265]  [<ffffffff817cdaaf>] schedule+0x3f/0xa0
> > [ 5535.968817]  [<ffffffff817d33fb>] schedule_timeout+0x3db/0x6f0
> > [ 5535.975346]  [<ffffffff817cf055>] ? wait_for_completion+0x45/0x130
> > [ 5535.982256]  [<ffffffff817cf0d3>] wait_for_completion+0xc3/0x130
> > [ 5535.988972]  [<ffffffff810d1fd0>] ? wake_up_q+0x80/0x80
> > [ 5535.994804]  [<ffffffff8130de64>] drop_sysctl_table+0xc4/0xe0
> > [ 5536.001227]  [<ffffffff8130de17>] drop_sysctl_table+0x77/0xe0
> > [ 5536.007648]  [<ffffffff8130decd>] unregister_sysctl_table+0x4d/0xa0
> > [ 5536.014654]  [<ffffffff8130deff>] unregister_sysctl_table+0x7f/0xa0
> > [ 5536.021657]  [<ffffffff810f57f5>]
> > unregister_sched_domain_sysctl+0x15/0x40
> > [ 5536.029344]  [<ffffffff810d7704>] partition_sched_domains+0x44/0x450
> > [ 5536.036447]  [<ffffffff817d0761>] ? __mutex_unlock_slowpath+0x111/0x1f0
> > [ 5536.043844]  [<ffffffff81167684>] rebuild_sched_domains_locked+0x64/0xb0
> > [ 5536.051336]  [<ffffffff8116789d>] update_flag+0x11d/0x210
> > [ 5536.057373]  [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450
> > [ 5536.064186]  [<ffffffff81167acb>] ? cpuset_css_offline+0x1b/0x60
> > [ 5536.070899]  [<ffffffff810fce3d>] ? trace_hardirqs_on+0xd/0x10
> > [ 5536.077420]  [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450
> > [ 5536.084234]  [<ffffffff8115a9f5>] ? css_killed_work_fn+0x25/0x220
> > [ 5536.091049]  [<ffffffff81167ae5>] cpuset_css_offline+0x35/0x60
> > [ 5536.097571]  [<ffffffff8115aa2c>] css_killed_work_fn+0x5c/0x220
> > [ 5536.104207]  [<ffffffff810bc83f>] process_one_work+0x1df/0x710
> > [ 5536.110736]  [<ffffffff810bc7c0>] ? process_one_work+0x160/0x710
> > [ 5536.117461]  [<ffffffff810bce9b>] worker_thread+0x12b/0x4a0
> > [ 5536.123697]  [<ffffffff810bcd70>] ? process_one_work+0x710/0x710
> > [ 5536.130426]  [<ffffffff810c3f7e>] kthread+0xfe/0x120
> > [ 5536.135991]  [<ffffffff817d4baf>] ret_from_fork+0x1f/0x40
> > [ 5536.142041]  [<ffffffff810c3e80>] ? kthread_create_on_node+0x230/0x230
> 
> This one seems to be the offender.  cgroup is trying to offline a
> cpuset css, which takes place under cgroup_mutex.  The offlining ends
> up trying to drain active usages of a sysctl table which apprently is
> not happening.  Did something hang or crash while trying to generate
> sysctl content?
Hmm, I am not sure, since the trinity was running from an non-privileged
user which can only read content from /proc or /sys.
    CAI Qian

  reply index

Thread overview: 101+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20160908235521.GL2356@ZenIV.linux.org.uk>
     [not found] ` <20160909015324.GD30056@dastard>
     [not found]   ` <CA+55aFzohsUXj_3BeFNr2t50Wm=G+7toRDEz=Tk7VJqP3n1hXQ@mail.gmail.com>
     [not found]     ` <CA+55aFxrqCng2Qxasc9pyMrKUGFjo==fEaFT1vkH9Lncte3RgQ@mail.gmail.com>
     [not found]       ` <20160909023452.GO2356@ZenIV.linux.org.uk>
     [not found]         ` <CA+55aFwHQMjO4-vtfB9-ytc=o+DRo-HXVGckvXLboUxgpwb7_g@mail.gmail.com>
     [not found]           ` <20160909221945.GQ2356@ZenIV.linux.org.uk>
     [not found]             ` <CA+55aFzTOOB6oEVaaGD0N7Uznk-W9+ULPwzsxS_L_oZqGVSeLA@mail.gmail.com>
     [not found]               ` <20160914031648.GB2356@ZenIV.linux.org.uk>
     [not found]                 ` <20160914133925.2fba4629@roar.ozlabs.ibm.com>
2016-09-18  5:33                   ` xfs_file_splice_read: possible circular locking dependency detected Al Viro
2016-09-19  3:08                     ` Nicholas Piggin
2016-09-19  6:11                       ` Al Viro
2016-09-19  7:26                         ` Nicholas Piggin
     [not found]                 ` <CA+55aFznQaOWoSMNphgGJJWZ=8-odrc0DAUMzfGPQe+_N4UgNA@mail.gmail.com>
     [not found]                   ` <20160914042559.GC2356@ZenIV.linux.org.uk>
     [not found]                     ` <20160917082007.GA6489@ZenIV.linux.org.uk>
     [not found]                       ` <20160917190023.GA8039@ZenIV.linux.org.uk>
2016-09-18 19:31                         ` skb_splice_bits() and large chunks in pipe (was " Al Viro
2016-09-18 20:12                           ` Linus Torvalds
2016-09-18 22:31                             ` Al Viro
2016-09-19  0:18                               ` Linus Torvalds
2016-09-23 19:00                         ` [RFC][CFT] splice_read reworked Al Viro
2016-09-23 19:01                           ` [PATCH 01/11] fix memory leaks in tracing_buffers_splice_read() Al Viro
2016-09-23 19:02                           ` [PATCH 02/11] splice_to_pipe(): don't open-code wakeup_pipe_readers() Al Viro
2016-09-23 19:02                           ` [PATCH 03/11] splice: switch get_iovec_page_array() to iov_iter Al Viro
2016-09-23 19:03                           ` [PATCH 04/11] splice: lift pipe_lock out of splice_to_pipe() Al Viro
2016-09-23 19:45                             ` Linus Torvalds
2016-09-23 20:10                               ` Al Viro
2016-09-23 20:36                                 ` Linus Torvalds
2016-09-24  3:59                                   ` Al Viro
2016-09-24 17:29                                     ` Al Viro
2016-09-27 15:38                                       ` Nicholas Piggin
2016-09-27 15:53                                       ` Chuck Lever
2016-09-24  3:59                                   ` [PATCH 04/12] " Al Viro
2016-09-26 13:35                                     ` Miklos Szeredi
2016-09-27  4:14                                       ` Al Viro
2016-12-17 19:54                                     ` Andreas Schwab
2016-12-18 19:28                                       ` Linus Torvalds
2016-12-18 19:57                                         ` Andreas Schwab
2016-12-18 20:12                                         ` Al Viro
2016-12-18 20:30                                           ` Al Viro
2016-12-18 22:10                                             ` Linus Torvalds
2016-12-18 22:18                                               ` Al Viro
2016-12-18 22:22                                                 ` Linus Torvalds
2016-12-18 22:49                                               ` Andreas Schwab
2016-12-21 18:56                                               ` Andreas Schwab
2016-12-21 19:12                                                 ` Linus Torvalds
2016-09-24  4:00                                   ` [PATCH 06/12] new helper: add_to_pipe() Al Viro
2016-09-26 13:49                                     ` Miklos Szeredi
2016-09-24  4:01                                   ` [PATCH 10/12] new iov_iter flavour: pipe-backed Al Viro
2016-09-29 20:53                                     ` Miklos Szeredi
2016-09-29 22:50                                       ` Al Viro
2016-09-30  7:30                                         ` Miklos Szeredi
2016-10-03  3:34                                           ` [RFC] O_DIRECT vs EFAULT (was Re: [PATCH 10/12] new iov_iter flavour: pipe-backed) Al Viro
2016-10-03 17:07                                             ` Linus Torvalds
2016-10-03 18:54                                               ` Al Viro
2016-09-24  4:01                                   ` [PATCH 11/12] switch generic_file_splice_read() to use of ->read_iter() Al Viro
2016-09-24  4:02                                   ` [PATCH 12/12] switch default_file_splice_read() to use of pipe-backed iov_iter Al Viro
2016-09-23 19:03                           ` [PATCH 05/11] skb_splice_bits(): get rid of callback Al Viro
2016-09-23 19:04                           ` [PATCH 06/11] new helper: add_to_pipe() Al Viro
2016-09-23 19:04                           ` [PATCH 07/11] fuse_dev_splice_read(): switch to add_to_pipe() Al Viro
2016-09-23 19:06                           ` [PATCH 08/11] cifs: don't use memcpy() to copy struct iov_iter Al Viro
2016-09-23 19:08                           ` [PATCH 09/11] fuse_ioctl_copy_user(): don't open-code copy_page_{to,from}_iter() Al Viro
2016-09-26  9:31                             ` Miklos Szeredi
2016-09-23 19:09                           ` [PATCH 10/11] new iov_iter flavour: pipe-backed Al Viro
2016-09-23 19:10                           ` [PATCH 11/11] switch generic_file_splice_read() to use of ->read_iter() Al Viro
2016-09-30 13:32                           ` [RFC][CFT] splice_read reworked CAI Qian
2016-09-30 17:42                             ` CAI Qian
2016-09-30 18:33                               ` CAI Qian
2016-10-03  1:37                                 ` Al Viro
2016-10-03 17:49                                   ` CAI Qian
2016-10-04 17:39                                     ` local DoS - systemd hang or timeout (WAS: Re: [RFC][CFT] splice_read reworked) CAI Qian
2016-10-04 21:42                                       ` tj
2016-10-05 14:09                                         ` CAI Qian [this message]
2016-10-05 15:30                                           ` tj
2016-10-05 15:54                                             ` CAI Qian
2016-10-05 18:57                                               ` CAI Qian
2016-10-05 20:05                                                 ` Al Viro
2016-10-06 12:20                                                   ` CAI Qian
2016-10-06 12:25                                                     ` CAI Qian
2016-10-06 16:11                                                       ` CAI Qian
2016-10-06 17:00                                                         ` Linus Torvalds
2016-10-06 18:12                                                           ` CAI Qian
2016-10-07  9:57                                                           ` Dave Chinner
2016-10-07 15:25                                                             ` Linus Torvalds
2016-10-07  7:08                                                       ` Jan Kara
2016-10-07 14:43                                                         ` CAI Qian
2016-10-07 15:27                                                           ` CAI Qian
2016-10-07 18:56                                                             ` CAI Qian
2016-10-09 21:54                                                               ` Dave Chinner
2016-10-10 14:10                                                                 ` CAI Qian
2016-10-10 20:14                                                                   ` CAI Qian
2016-10-10 21:57                                                                   ` Dave Chinner
2016-10-12 19:50                                                                     ` [bisected] " CAI Qian
2016-10-12 20:59                                                                       ` Dave Chinner
2016-10-13 16:25                                                                         ` CAI Qian
2016-10-13 20:49                                                                           ` Dave Chinner
2016-10-13 20:56                                                                             ` CAI Qian
2016-10-09 21:51                                                           ` Dave Chinner
2016-10-21 15:38                                                         ` [4.9-rc1+] overlayfs lockdep CAI Qian
2016-10-24 12:57                                                           ` Miklos Szeredi
2016-10-07  9:27                                                     ` local DoS - systemd hang or timeout (WAS: Re: [RFC][CFT] splice_read reworked) Dave Chinner
2016-10-03  1:42                               ` [RFC][CFT] splice_read reworked Al Viro
2016-10-03 14:06                                 ` CAI Qian
2016-10-03 15:20                                   ` CAI Qian
2016-10-03 21:12                                     ` Dave Chinner
2016-10-04 13:57                                       ` CAI Qian
2016-10-03 20:32                                   ` CAI Qian
2016-10-03 20:35                                     ` Al Viro
2016-10-04 13:29                                       ` CAI Qian
2016-10-04 14:28                                         ` Al Viro
2016-10-04 16:21                                           ` CAI Qian
2016-10-04 20:12                                             ` Al Viro
2016-10-05 14:30                                               ` CAI Qian
2016-10-05 16:07                                                 ` Al Viro
2016-09-19  0:22 skb_splice_bits() and large chunks in pipe (was Re: xfs_file_splice_read: possible circular locking dependency detected Al Viro
2016-09-20  9:51 ` Herbert Xu

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