From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Ross Zwisler <zwisler@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Petr Mladek <pmladek@suse.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jan Kara <jack@suse.cz>, Tejun Heo <tj@kernel.org>,
Calvin Owens <calvinowens@fb.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
Peter Hurley <peter@hurleysoftware.com>,
LKML <linux-kernel@vger.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCHv7 6/8] printk: use printk_safe buffers in printk
Date: Thu, 2 Feb 2017 10:59:37 +0900 [thread overview]
Message-ID: <20170202015937.GA1954@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <CAOxpaSWz_mJNQFj1NCfmaZU_tzAw34SN9CfH+55o8J+WEkcmxA@mail.gmail.com>
Hello Ross,
I was offline for a week for personal reasons.
On (01/31/17 10:27), Ross Zwisler wrote:
[..]
> [ 13.090634] ======================================================
> [ 13.090634] [ INFO: possible circular locking dependency detected ]
> [ 13.090635] 4.10.0-rc5-mm1-00313-g5c0c3d7-dirty #10 Not tainted
> [ 13.090635] -------------------------------------------------------
> [ 13.090635] systemd/1 is trying to acquire lock:
> [ 13.090636] ((console_sem).lock){-.....}, at: [<ffffffff81110194>]
> down_trylock+0x14/0x40
> [ 13.090637]
> [ 13.090637] but task is already holding lock:
> [ 13.090637] (&rq->lock){-.-.-.}, at: [<ffffffff810e6116>]
> task_rq_lock+0x56/0xd0
> [ 13.090638]
> [ 13.090639] which lock already depends on the new lock.
> [ 13.090639]
> [ 13.090639]
> [ 13.090640] the existing dependency chain (in reverse order) is:
> [ 13.090640] c
> [ 13.090640] -> #2 (&rq->lock){-.-.-.}:
> [ 13.090641] [<ffffffff8111727d>] lock_acquire+0xfd/0x200
> [ 13.090642] [<ffffffff81ca3171>] _raw_spin_lock+0x41/0x80
> [ 13.090642] [<ffffffff810fa38a>] task_fork_fair+0x3a/0x100
> [ 13.090642] [<ffffffff810ea80d>] sched_fork+0x10d/0x2c0
> [ 13.090643] [<ffffffff810b05df>] copy_process.part.30+0x69f/0x2190
> [ 13.090643] [<ffffffff810b22c6>] _do_fork+0xf6/0x700
> [ 13.090643] [<ffffffff810b28f9>] kernel_thread+0x29/0x30
> [ 13.090644] [<ffffffff81c91572>] rest_init+0x22/0x140
> [ 13.090644] [<ffffffff8280b051>] start_kernel+0x461/0x482
> [ 13.090644] [<ffffffff8280a2d6>] x86_64_start_reservations+0x2a/0x2c
> [ 13.090645] [<ffffffff8280a424>] x86_64_start_kernel+0x14c/0x16f
> [ 13.090645] [<ffffffff810001c4>] verify_cpu+0x0/0xfc
> [ 13.090645]
> [ 13.090645] -> #1 (&p->pi_lock){-.-.-.}:
> [ 13.090647] [<ffffffff8111727d>] lock_acquire+0xfd/0x200
> [ 13.090647] [<ffffffff81ca3f79>] _raw_spin_lock_irqsave+0x59/0x93
> [ 13.090647] [<ffffffff810e943f>] try_to_wake_up+0x3f/0x530
> [ 13.090648] [<ffffffff810e9945>] wake_up_process+0x15/0x20
> [ 13.090648] [<ffffffff81c9fc4c>] __up.isra.0+0x4c/0x50
> [ 13.090648] [<ffffffff81110256>] up+0x46/0x50
> [ 13.090649] [<ffffffff81128a55>] __up_console_sem+0x45/0x80
> [ 13.090649] [<ffffffff81129baf>] console_unlock+0x29f/0x5e0
> [ 13.090649] [<ffffffff8112a1c0>] vprintk_emit+0x2d0/0x3a0
> [ 13.090650] [<ffffffff8112a429>] vprintk_default+0x29/0x50
> [ 13.090650] [<ffffffff8112b445>] vprintk_func+0x25/0x80
> [ 13.090650] [<ffffffff81205c6d>] printk+0x52/0x6e
> [ 13.090651] [<ffffffff81185bdc>] kauditd_hold_skb+0x9c/0xa0
> [ 13.090651] [<ffffffff8118601b>] kauditd_thread+0x23b/0x520
> [ 13.090651] [<ffffffff810dbb6f>] kthread+0x10f/0x150
> [ 13.090652] [<ffffffff81ca42c1>] ret_from_fork+0x31/0x40
> [ 13.090652]
> [ 13.090652] -> #0 ((console_sem).lock){-.....}:
> [ 13.090653] [<ffffffff81116c85>] __lock_acquire+0x10e5/0x1270
> [ 13.090653] [<ffffffff8111727d>] lock_acquire+0xfd/0x200
> [ 13.090654] [<ffffffff81ca3f79>] _raw_spin_lock_irqsave+0x59/0x93
> [ 13.090654] [<ffffffff81110194>] down_trylock+0x14/0x40
> [ 13.090654] [<ffffffff81128b7c>] __down_trylock_console_sem+0x3c/0xc0
> [ 13.090655] [<ffffffff81128c16>] console_trylock+0x16/0x90
> [ 13.090655] [<ffffffff8112a1b7>] vprintk_emit+0x2c7/0x3a0
> [ 13.090655] [<ffffffff8112a429>] vprintk_default+0x29/0x50
> [ 13.090656] [<ffffffff8112b445>] vprintk_func+0x25/0x80
> [ 13.090656] [<ffffffff81205c6d>] printk+0x52/0x6e
> [ 13.090656] [<ffffffff810b3329>] __warn+0x39/0xf0
> [ 13.090657] [<ffffffff810b343f>] warn_slowpath_fmt+0x5f/0x80
> [ 13.090657] [<ffffffff810f550b>] update_load_avg+0x85b/0xb80
> [ 13.090657] [<ffffffff810f58bf>] detach_task_cfs_rq+0x3f/0x210
> [ 13.090658] [<ffffffff810f8e34>] task_change_group_fair+0x24/0x100
> [ 13.090658] [<ffffffff810e46ef>] sched_change_group+0x5f/0x110
> [ 13.090658] [<ffffffff810efd03>] sched_move_task+0x53/0x160
> [ 13.090659] [<ffffffff810efe46>] cpu_cgroup_attach+0x36/0x70
> [ 13.090659] [<ffffffff81172aa0>] cgroup_migrate_execute+0x230/0x3f0
> [ 13.090659] [<ffffffff81172d2e>] cgroup_migrate+0xce/0x140
> [ 13.090660] [<ffffffff8117301f>] cgroup_attach_task+0x27f/0x3e0
> [ 13.090660] [<ffffffff81175b7e>] __cgroup_procs_write+0x30e/0x510
> [ 13.090661] [<ffffffff81175d94>] cgroup_procs_write+0x14/0x20
> [ 13.090661] [<ffffffff811700e4>] cgroup_file_write+0x44/0x1e0
> [ 13.090661] [<ffffffff8135a92c>] kernfs_fop_write+0x13c/0x1c0
> [ 13.090662] [<ffffffff812b8e07>] __vfs_write+0x37/0x160
> [ 13.090662] [<ffffffff812ba8ab>] vfs_write+0xcb/0x1f0
> [ 13.090662] [<ffffffff812bbe38>] SyS_write+0x58/0xc0
> [ 13.090663] [<ffffffff81ca4041>] entry_SYSCALL_64_fastpath+0x1f/0xc2
... so it looks like a printk() from the scheduler; I don't think it's
related to printk_safe(). and to make it worse, printk is not in safe mode
when sched_move_task()->update_load_avg() calls it... so the system is
free to deadlock. we need printk_deferred() patch here.
I may be wrong, I just saw the message -- so this is a rather quick reply.
does the patch below fix the problem for you?
https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?h=sched/core&id=1b1d62254df0fe42a711eb71948f915918987790
-ss
next prev parent reply other threads:[~2017-02-02 1:59 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-27 14:16 [PATCHv7 0/8] printk: use printk_safe to handle printk() recursive calls Sergey Senozhatsky
2016-12-27 14:16 ` [PATCHv7 1/8] printk: use vprintk_func in vprintk() Sergey Senozhatsky
2016-12-27 14:16 ` [PATCHv7 2/8] printk: rename nmi.c and exported api Sergey Senozhatsky
2017-01-04 13:07 ` Petr Mladek
2017-02-01 15:48 ` Steven Rostedt
2017-02-01 15:50 ` Steven Rostedt
2017-02-23 7:50 ` Geert Uytterhoeven
2017-02-23 8:02 ` Sergey Senozhatsky
2017-02-23 9:23 ` Geert Uytterhoeven
2016-12-27 14:16 ` [PATCHv7 3/8] printk: introduce per-cpu safe_print seq buffer Sergey Senozhatsky
2017-01-04 13:31 ` Petr Mladek
2017-01-05 1:01 ` Sergey Senozhatsky
2017-02-01 15:52 ` Steven Rostedt
2016-12-27 14:16 ` [PATCHv7 4/8] printk: always use deferred printk when flush printk_safe lines Sergey Senozhatsky
2017-02-01 16:06 ` Steven Rostedt
2017-02-02 6:05 ` Sergey Senozhatsky
2017-02-02 15:37 ` Petr Mladek
2017-02-02 15:52 ` Petr Mladek
2017-02-03 2:04 ` Sergey Senozhatsky
2017-02-03 11:18 ` Petr Mladek
2017-02-06 1:48 ` Sergey Senozhatsky
2017-02-06 2:08 ` Sergey Senozhatsky
2017-02-06 12:16 ` Petr Mladek
2017-02-06 13:27 ` Steven Rostedt
2017-02-06 16:42 ` Sergey Senozhatsky
2017-02-06 16:55 ` Steven Rostedt
2016-12-27 14:16 ` [PATCHv7 5/8] printk: report lost messages in printk safe/nmi contexts Sergey Senozhatsky
2017-01-04 14:46 ` Petr Mladek
2017-01-05 1:01 ` Sergey Senozhatsky
2017-02-01 16:37 ` Steven Rostedt
2017-02-02 2:02 ` Sergey Senozhatsky
2017-02-02 14:34 ` Steven Rostedt
2017-02-02 16:13 ` Petr Mladek
2017-02-03 1:57 ` Sergey Senozhatsky
2017-02-03 3:13 ` Steven Rostedt
2016-12-27 14:16 ` [PATCHv7 6/8] printk: use printk_safe buffers in printk Sergey Senozhatsky
2017-01-31 17:27 ` Ross Zwisler
2017-02-01 9:06 ` Jan Kara
2017-02-01 9:37 ` Peter Zijlstra
2017-02-01 15:39 ` Petr Mladek
2017-02-01 16:15 ` Peter Zijlstra
2017-02-01 16:41 ` Steven Rostedt
2017-02-02 2:11 ` Sergey Senozhatsky
2017-02-02 9:07 ` Peter Zijlstra
2017-02-02 10:03 ` Sergey Senozhatsky
2017-02-02 15:20 ` Petr Mladek
2017-02-03 2:45 ` Sergey Senozhatsky
2017-02-02 1:59 ` Sergey Senozhatsky [this message]
2017-02-01 17:04 ` Steven Rostedt
2017-02-02 2:13 ` Sergey Senozhatsky
2016-12-27 14:16 ` [PATCHv7 7/8] printk: remove zap_locks() function Sergey Senozhatsky
2016-12-27 14:16 ` [PATCHv7 8/8] printk: convert the rest to printk-safe Sergey Senozhatsky
2017-01-04 16:28 ` Petr Mladek
2017-01-05 1:00 ` Sergey Senozhatsky
2017-01-05 16:58 ` [PATCHv7 0/8] printk: use printk_safe to handle printk() recursive calls Petr Mladek
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