On Sun, Jan 20, 2013 at 1:06 AM, Sedat Dilek [off-list ref] wrote:

On Sun, Jan 20, 2013 at 12:44 AM, Sedat Dilek [off-list ref] wrote:

quoted

Hi,

I and some others hit a similiar problem in Linux-Next
(next-20130118), please see [1] and [2].

[3] has a interim analyze of my problems.

After suspecting the problem was caused by TTY-NEXT, it turned out to
be a JBD2 problem finally.
The freezer/pm_test was helpful to hit the issue (Thanks Rafael for the hint!).

So, the issue has two faces: TTY and JBD2.
[4] gives a list and URLs of the patches I had to apply to have a
clean system again.

After applying the two TTY patches (without Eric's JBD2-fix!) the
call-trace after freezer/pm_test looked 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

After applying Eric's patch [5], I could not hit the call-trace again.
NOTE: The patch is from December 2012 and is not shipped in latest Linux-Next.

The attached testcase script was helpful to force the call-trace.
I have run 50 loops of it w/o an issue!

Feel free to add a Reported-by/Tested-by.
( The issue kept me busy for the last days. )

Regards,
- Sedat -

[1] http://marc.info/?t=135283664600002&r=1&w=2
[2] http://marc.info/?t=135862023700004&r=1&w=2
[3] http://marc.info/?l=linux-kernel&m=135862010419101&w=2
[4] http://marc.info/?l=linux-next&m=135863550923093&w=2
[5] http://patchwork.ozlabs.org/patch/207237/

Hi all,

this is really ugly... I could cry!

GRRR, I have hit the original issue again while running my testcase script!

[  363.831226] PM: Syncing filesystems ... done.
[  363.988855] PM: Preparing system for mem sleep
[  369.032965] Freezing user space processes ... (elapsed 0.11 seconds) done.
[  369.145792] Freezing remaining freezable tasks ...
[  389.137643] Freezing of tasks failed after 20.01 seconds (1 tasks
refusing to freeze, wq_busy=0):
[  389.137760] jbd2/loop0-8    D ffffffff8180d780     0   295      2 0x00000000
[  389.137769]  ffff8801181dfb68 0000000000000046 ffff880117de5c80
0000000000000001
[  389.137778]  ffff880117de5c80 ffff8801181dffd8 ffff8801181dffd8
ffff8801181dffd8
[  389.137784]  ffffffff81c15440 ffff880117de5c80 ffff8801181dfb68
ffff88011fa14738
[  389.137791] Call Trace:
[  389.137810]  [<ffffffff811c6830>] ? __wait_on_buffer+0x30/0x30
[  389.137819]  [<ffffffff816b7479>] schedule+0x29/0x70
[  389.137825]  [<ffffffff816b754f>] io_schedule+0x8f/0xd0
[  389.137832]  [<ffffffff811c683e>] sleep_on_buffer+0xe/0x20
[  389.137842]  [<ffffffff816b5d4f>] __wait_on_bit+0x5f/0x90
[  389.137849]  [<ffffffff811c5ef1>] ? submit_bh+0x121/0x1e0
[  389.137856]  [<ffffffff811c6830>] ? __wait_on_buffer+0x30/0x30
[  389.137864]  [<ffffffff816b5dfc>] out_of_line_wait_on_bit+0x7c/0x90
[  389.137873]  [<ffffffff8107eb00>] ? autoremove_wake_function+0x40/0x40
[  389.137879]  [<ffffffff811c682e>] __wait_on_buffer+0x2e/0x30
[  389.137891]  [<ffffffff8128c02c>]
jbd2_journal_commit_transaction+0x18cc/0x1d60
[  389.137899]  [<ffffffff816b860e>] ? _raw_spin_lock_irqsave+0x2e/0x40
[  389.137908]  [<ffffffff81069fbf>] ? try_to_del_timer_sync+0x4f/0x70
[  389.137915]  [<ffffffff81290836>] kjournald2+0xd6/0x3e0
[  389.137921]  [<ffffffff8107eac0>] ? add_wait_queue+0x60/0x60
[  389.137926]  [<ffffffff81290760>] ? commit_timeout+0x10/0x10
[  389.137932]  [<ffffffff8107ded0>] kthread+0xc0/0xd0
[  389.137939]  [<ffffffff8107de10>] ? flush_kthread_worker+0xb0/0xb0
[  389.137946]  [<ffffffff816c0e2c>] ret_from_fork+0x7c/0xb0
[  389.137951]  [<ffffffff8107de10>] ? flush_kthread_worker+0xb0/0xb0
[  389.138017]
[  389.138021] Restarting kernel threads ... done.
[  389.138173] Restarting tasks ... done.
[  389.147980] video LNXVIDEO:00: Restoring backlight state

I suspect there are still issues in JBD2 (BTW I run here EXT4FS).

[  389.137643] Freezing of tasks failed after 20.01 seconds (1 tasks
refusing to freeze, wq_busy=0):
[  389.137760] jbd2/loop0-8    D ffffffff8180d780     0   295      2 0x00000000

Have a good night, /me -> watching TV!

- Sedat -

Man, what a NONSENSE I am telling...
The mentioned so-called fix is already in next-20130118, shame on me!

commit 7e2fb2d7e6a3094473f101ae33dd6431ae6d2ed1
"jbd: don't wake kjournald unnecessarily"

- Sedat -

[1] http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git;a=commitdiff;h=7e2fb2d7e6a3094473f101ae33dd6431ae6d2ed1