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Message-ID: <CA+icZUUs8jihz6rt2DRL5BixoVVjEbtO0fkQKs0UOUTV07KNJw@mail.gmail.com>
Date: Sat, 19 Jan 2013 23:10:47 +0100
From: Sedat Dilek <sedat.dilek@...il.com>
To: linux-next <linux-next@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Linux PM List <linux-pm@...ts.linux-foundation.org>,
linux-serial@...r.kernel.org,
linux-fsdevel <linux-fsdevel@...r.kernel.org>, x86@...nel.org,
"Rafael J. Wysocki" <rjw@...k.pl>, Ilya Zykov <ilya@...x.ru>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.cz>, "Theodore Ts'o" <tytso@....edu>,
Thomas Gleixner <tglx@...utronix.de>,
Paul McKenney <paul.mckenney@...aro.org>,
Paul McKenney <paulmck@...ux.vnet.ibm.com>,
Jan Kara <jack@...e.cz>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Eric Sandeen <sandeen@...hat.com>
Subject: Re: [next-20130118] Analyzing a call-trace reproducible with
pm_test/freezer [ X86|RCU|TTY|EXT4FS|JBD2|PM related? ]
On Sat, Jan 19, 2013 at 10:26 PM, Sedat Dilek <sedat.dilek@...il.com> wrote:
> On Sat, Jan 19, 2013 at 9:48 PM, Sedat Dilek <sedat.dilek@...il.com> wrote:
>> On Sat, Jan 19, 2013 at 7:28 PM, Sedat Dilek <sedat.dilek@...il.com> wrote:
>>> Hi,
>>>
>>> I am still stepping in the dark how track this problem down.
>>> If you have useful (debug) help, you are welcome.
>>>
>>> Regards,
>>> - Sedat -
>>>
>>> ##### ANALYZING CALL-TRACES SEEN IN LINUX-NEXT-20130118 #####
>>>
>>> ##### INTRO
>>>
>>> ### MY LINUX-SYSTEM
>>>
>>> I am running here Ubuntu/precise AMD64 in a WUBI environment.
>>> The system was formatted with EXT4-FS.
>>>
>>> ### MY LINUX-KERNEL
>>>
>>> My own built Linux-Next (next-20130118) kernel includes some additional patches,
>>> especially a TTY-NEXT fix from Ilya Zykov.
>>>
>>> See also attached kernel-config file, dmesg and lspci outputs.
>>>
>>> ### SOME USEFUL KERNEL DEBUG OPTIONS
>>>
>>> CONFIG_PM_DEBUG=y
>>> CONFIG_EXT4_DEBUG=y
>>> CONFIG_JBD2_DEBUG=y
>>>
>>>
>>> ##### [A] ANALYZING LAST REBOOT
>>>
>>> ### [A.1] MESSAGES
>>>
>>> # Messages #1: DBUS related?
>>> nm-dispatcher.action: Could not get the system bus. Make sure the
>>> message bus daemon is running! Message: Failed to connect to socket
>>> /var/run/dbus/system_bus_socket: No such file or directory
>>>
>>> # Messages #2: RCU_SCHED related?
>>> INFO: rcu_sched detected stalls on CPUs/tasks: { 2 3} (detected by 1,
>>> t=15004 jiffies, g=70928, c=70927, q=15)
>>> INFO: task kworker/0:1:37 blocked for more than 120 seconds. "echo 0 >
>>> /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>>
>>> ### [A.2] ANALYZING DBUS PROBLEM
>>>
>>> # ll /var/run/dbus/system_bus_socket*
>>> srwxrwxrwx 1 root root 0 Jan 19 17:08 /var/run/dbus/system_bus_socket=
>>>
>>> # ll /var/run/dbus/
>>> insgesamt 4
>>> drwxr-xr-x 2 messagebus messagebus 80 Jan 19 17:08 ./
>>> drwxr-xr-x 22 root root 800 Jan 19 17:11 ../
>>> -rw-r--r-- 1 root root 4 Jan 19 17:08 pid
>>> srwxrwxrwx 1 root root 0 Jan 19 17:08 system_bus_socket=
>>>
>>> # cat /var/run/dbus/pid
>>> 862
>>>
>>> # ps axu | grep -v grep | grep 862
>>> 102 862 0.2 0.0 25492 2332 ? Ss 17:08 0:01
>>> dbus-daemon --system --fork --activation=upstart
>>>
>>> # pidof dbus-daemon
>>> 1921 862
>>>
>>> ### [A.3] ANALYZING RCU_SCHED PROBLEM
>>>
>>> # cat /proc/sys/kernel/hung_task_timeout_secs
>>> 120
>>>
>>>
>>> ##### [B] TESTCASE DESCRIPTION
>>>
>>> ### [B.1] TESTCASE #1: Do a "normal" suspend and resume
>>>
>>> Select "suspend" (DE: "Bereitschaft") from system's menue within Ubuntu/unity.
>>>
>>> ### [B.2] TESTCASE #2: Run pm_test/freezer (PREREQ: CONFIG_PM_DEBUG=y)
>>>
>>> HELP: <http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=Documentation/power/basic-pm-debugging.txt#l184>
>>>
>>> # cat /sys/power/pm_test
>>> [none] core processors platform devices freezer
>>>
>>> # echo "freezer" > /sys/power/pm_test
>>> # cat /sys/power/pm_test
>>> none core processors platform devices [freezer]
>>>
>>> # echo mem > /sys/power/state && sleep 1 <--- LOOP until you see a call-trace
>>>
>>> ### [B.3] TESTCASE #3: Change "hung_task_timeout_secs" before running
>>> pm_test/freezer
>>>
>>> # cat /proc/sys/kernel/hung_task_timeout_secs
>>> 120
>>>
>>> # echo 0 > /proc/sys/kernel/hung_task_timeout_secs
>>> # cat /proc/sys/kernel/hung_task_timeout_secs
>>> 0
>>>
>>>
>>> ##### [C] THE CALL-TRACE
>>>
>>> ### [C.1] TRY TO FORCE THE CALL-TRACE
>>>
>>> The call-trace is not ***always*** reproducible!
>>> Even with "0" for "hung_task_timeout_secs" it is seen (see testcase #3)!
>>>
>>> The call-trace ***always*** happened when the output "-su: echo: write
>>> error: Device or resource busy" was seen!
>>> Unsure, how to intpret it!
>>> What means "-su"?
>>> Write-error to which device?
>>> Which resource is busy?
>>>
>>> # LC_ALL=C echo mem > /sys/power/state && sleep 1
>>> -su: echo: write error: Device or resource busy <--- THIS OUTPUT!
>>>
>>> [ /var/log/kern.log ]
>>>
>>> n 19 18:00:02 fambox kernel: [ 3065.559184] PM: Syncing filesystems ... done.
>>> Jan 19 18:00:02 fambox kernel: [ 3065.768458] PM: Preparing system for mem sleep
>>> Jan 19 18:00:14 fambox kernel: [ 3072.733178] Freezing user space
>>> processes ... (elapsed 0.01 seconds) done.
>>> Jan 19 18:00:14 fambox kernel: [ 3072.749284] Freezing remaining
>>> freezable tasks ... (elapsed 0.01 seconds) done.
>>> Jan 19 18:00:14 fambox kernel: [ 3072.765274] suspend debug: Waiting
>>> for 5 seconds.
>>> Jan 19 18:00:14 fambox kernel: [ 3077.722222] PM: Finishing wakeup.
>>> Jan 19 18:00:14 fambox kernel: [ 3077.722224] Restarting tasks ... done.
>>> Jan 19 18:00:14 fambox kernel: [ 3077.726719] video LNXVIDEO:00:
>>> Restoring backlight state
>>> Jan 19 18:00:18 fambox kernel: [ 3081.596512] PM: Syncing filesystems ... done.
>>> Jan 19 18:00:18 fambox kernel: [ 3081.750235] PM: Preparing system for mem sleep
>>> Jan 19 18:00:45 fambox kernel: [ 3087.738204] Freezing user space
>>> processes ... (elapsed 0.04 seconds) done.
>>> Jan 19 18:00:45 fambox kernel: [ 3087.786660] Freezing remaining
>>> freezable tasks ...
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788540] Freezing of tasks failed
>>> after 20.01 seconds (1 tasks refusing to freeze, wq_busy=0):
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788664] jbd2/loop0-8 D
>>> ffffffff8180d780 0 299 2 0x00000000
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788673] ffff88011822db68
>>> 0000000000000046 ffff88011822db08 ffffffff81044c29
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788682] ffff880117c6dc80
>>> ffff88011822dfd8 ffff88011822dfd8 ffff88011822dfd8
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788689] ffffffff81c15440
>>> ffff880117c6dc80 ffff88011822db68 ffff88011fa14738
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788696] Call Trace:
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788715] [<ffffffff81044c29>] ?
>>> default_spin_lock_flags+0x9/0x10
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788726] [<ffffffff811c6830>] ?
>>> __wait_on_buffer+0x30/0x30
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788735] [<ffffffff816b7449>]
>>> schedule+0x29/0x70
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788741] [<ffffffff816b751f>]
>>> io_schedule+0x8f/0xd0
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788748] [<ffffffff811c683e>]
>>> sleep_on_buffer+0xe/0x20
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788758] [<ffffffff816b5d1f>]
>>> __wait_on_bit+0x5f/0x90
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788765] [<ffffffff811c5ef1>] ?
>>> submit_bh+0x121/0x1e0
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788771] [<ffffffff811c6830>] ?
>>> __wait_on_buffer+0x30/0x30
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788779] [<ffffffff816b5dcc>]
>>> out_of_line_wait_on_bit+0x7c/0x90
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788787] [<ffffffff8107eb00>] ?
>>> autoremove_wake_function+0x40/0x40
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788794] [<ffffffff811c682e>]
>>> __wait_on_buffer+0x2e/0x30
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788805] [<ffffffff8128c02c>]
>>> jbd2_journal_commit_transaction+0x18cc/0x1d60
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788814] [<ffffffff816b85de>] ?
>>> _raw_spin_lock_irqsave+0x2e/0x40
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788823] [<ffffffff81069fbf>] ?
>>> try_to_del_timer_sync+0x4f/0x70
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788830] [<ffffffff81290836>]
>>> kjournald2+0xd6/0x3e0
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788835] [<ffffffff8107eac0>] ?
>>> add_wait_queue+0x60/0x60
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788841] [<ffffffff81290760>] ?
>>> commit_timeout+0x10/0x10
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788846] [<ffffffff8107ded0>]
>>> kthread+0xc0/0xd0
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788852] [<ffffffff8107de10>] ?
>>> flush_kthread_worker+0xb0/0xb0
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788859] [<ffffffff816c0dec>]
>>> ret_from_fork+0x7c/0xb0
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788865] [<ffffffff8107de10>] ?
>>> flush_kthread_worker+0xb0/0xb0
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788929]
>>> Jan 19 18:00:45 fambox kernel: [ 3107.788932] Restarting kernel
>>> threads ... done.
>>> Jan 19 18:00:45 fambox kernel: [ 3107.789086] Restarting tasks ... done.
>>> Jan 19 18:00:45 fambox kernel: [ 3107.802117] video LNXVIDEO:00:
>>> Restoring backlight state
>>>
>>> ### [C.2] CHECKING DBUS AND RCU_SCHED STATUS POST-MORTEM
>>>
>>> # ll /var/run/dbus/
>>> insgesamt 4
>>> drwxr-xr-x 2 messagebus messagebus 80 Jan 19 17:08 ./
>>> drwxr-xr-x 22 root root 800 Jan 19 17:11 ../
>>> -rw-r--r-- 1 root root 4 Jan 19 17:08 pid
>>> srwxrwxrwx 1 root root 0 Jan 19 17:08 system_bus_socket=
>>>
>>> # cat /var/run/dbus/pid
>>> 862
>>>
>>> root@...box:~# ps axu | grep -v grep | grep 862
>>> 102 862 0.0 0.0 25492 2332 ? Ss 17:08 0:01
>>> dbus-daemon --system --fork --activation=upstart
>>> wearefam 1931 0.0 0.5 862752 20116 ? Sl 17:09 0:02
>>> /usr/lib/gnome-settings-daemon/gnome-settings-daemon
>>>
>>> # pidof dbus-daemon
>>> 1921 862
>>>
>>> # cat /proc/sys/kernel/hung_task_timeout_secs
>>> 0
>>>
>>>
>>> ##### [D] INTERIM SUMMARY
>>>
>>> 1. The issue is reproducible!
>>> 2. The issue ***can*** be forced by running pm_test/freezer!
>>>
>>> Again, the root cause is not very clear to me!
>>>
>>> Recent TTY-NEXT changes?
>>> Problems in EXT4-FS/JBD2?
>>> Problems in X86/RCU?
>>>
>>> Ask the experts :-)!
>>>
>>>
>>> -dileks // 19-Jan-2013
>>
>> I have a applied another pending patch ("tty: Add driver unthrottle in
>> ioctl(...,TCFLSH,..).") from tty-next.
>>
>> Now, the call-trace looks like this:
>>
>> [ 433.527986] PM: Syncing filesystems ... done.
>> [ 433.843761] PM: Preparing system for mem sleep
>> [ 436.306002] Freezing user space processes ...
>> [ 456.304956] Freezing of tasks failed after 20.01 seconds (1 tasks
>> refusing to freeze, wq_busy=0):
>> [ 456.305060] Cache I/O D ffffffff8180d780 0 2132 1 0x00000004
>> [ 456.305065] ffff88007b9dfe18 0000000000000046 ffff88007b9dfdc8
>> 0000000300000001
>> [ 456.305069] ffff880097e21720 ffff88007b9dffd8 ffff88007b9dffd8
>> ffff88007b9dffd8
>> [ 456.305072] ffff880119b32e40 ffff880097e21720 ffff88007b9dfe28
>> ffff880118077800
>> [ 456.305076] Call Trace:
>> [ 456.305085] [<ffffffff816b7469>] schedule+0x29/0x70
>> [ 456.305089] [<ffffffff8129067d>] jbd2_log_wait_commit+0xcd/0x1a0
>> [ 456.305094] [<ffffffff8107eac0>] ? add_wait_queue+0x60/0x60
>> [ 456.305098] [<ffffffff812307a5>] ext4_sync_file+0x205/0x380
>> [ 456.305103] [<ffffffff811c43ad>] do_fsync+0x5d/0x90
>> [ 456.305108] [<ffffffff8119442b>] ? sys_write+0x6b/0xa0
>> [ 456.305111] [<ffffffff811c4790>] sys_fsync+0x10/0x20
>> [ 456.305114] [<ffffffff816c0edd>] system_call_fastpath+0x1a/0x1f
>> [ 456.305122]
>> [ 456.305124] Restarting tasks ... done.
>> [ 456.315056] video LNXVIDEO:00: Restoring backlight state
>>
>> JBD2/EX4FS problem?
>>
>> - Sedat -
>>
>> [1] http://git.kernel.org/?p=linux/kernel/git/gregkh/tty.git;a=patch;h=a1bf9584429d61b7096f93ae09325e1ba538e9e8
>
> [ CC Eric Sandeen ]
>
> Looks like the patch " jbd2: don't wake kjournald unnecessarily" from
> Eric helps here.
> Still trying to reproduce the issue... but looks good so far!
>
> - Sedat -
>
> [1] http://patchwork.ozlabs.org/patch/207237/
As Rafael suggested me I have run my testcase 50 times and have seen
any call-traces in my logs!
>>>>> SNIP <<<<<
#!/bin/bash
export LANG=C
export LC_ALL=C
COUNTER=0
echo 0 > /proc/sys/kernel/hung_task_timeout_secs
echo "freezer" > /sys/power/pm_test
while [ $COUNTER -lt 50 ]; do
echo [ pm_test/freezer: Run $COUNTER ]
echo mem > /sys/power/state && sleep 1
echo [ pm_test/freezer: OK $COUNTER ]
let COUNTER=COUNTER+1
done
>>>>> SNAP <<<<<
- Sedat -
[1] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=Documentation/power/basic-pm-debugging.txt
[2] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=Documentation/power/freezing-of-tasks.txt
Download attachment "dmesg_freezer-pm-test.diff" of type "application/octet-stream" (49408 bytes)
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