Re: [GIT PULL rcu/urgent] Fix two more 4.3 regressions

[Sedat Dilek]

On Sun, Sep 27, 2015 at 5:58 PM, Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> On Sun, Sep 27, 2015 at 5:55 PM, Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
>> On Sun, Sep 27, 2015 at 5:49 PM, Paul E. McKenney
>> <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>>> On Sun, Sep 27, 2015 at 09:37:05AM +0200, Sedat Dilek wrote:
>>>> On Sun, Sep 27, 2015 at 9:32 AM, Paul E. McKenney
>>>> <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>>>> > On Sun, Sep 27, 2015 at 08:28:39AM +0200, Sedat Dilek wrote:
>>>> >> Hi,
>>>> >>
>>>> >> as I have observed here some lockdep issues (one could be solved in
>>>> >> netdev) I wanted to try this patchset.
>>>> >>
>>>> >> Unfortunately, you cannot pull from...
>>>> >>
>>>> >> "These changes are available in the git repository at:
>>>> >>
>>>> >>   git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo
>>>> >>
>>>> >> for you to fetch changes up to 19a5ecde086a6a5287978b12ae948fa691b197b7:
>>>> >>
>>>> >>   rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex
>>>> >> (2015-09-20 21:01:22 -0700)
>>>> >>
>>>> >> ----------------------------------------------------------------
>>>> >> Oleg Nesterov (1):
>>>> >>       rcu: Change _wait_rcu_gp() to work around GCC bug 67055
>>>> >>
>>>> >> Paul E. McKenney (1):
>>>> >>       rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex
>>>> >>
>>>> >>  include/linux/rcupdate.h | 11 +++++------
>>>> >>  kernel/rcu/tree.c        |  5 +++++
>>>> >>  2 files changed, 10 insertions(+), 6 deletions(-)"
>>>> >>
>>>> >> So, I have stolen them from linux-next.git.
>>>> >>
>>>> >> Please look at this, Thanks.
>>>> >
>>>> > Does it work better now?  (Forgot to actually push the new name...)
>>>>
>>>> Hi Paul,
>>>>
>>>> now for-mingo Git branch has this two fixes.
>>>
>>> Whew!!!  Apologies for the hassle!
>>>
>>>> I just booted into my new kernel with the "stolen" rcu.fixes from -next.
>>>>
>>>> For the lockdep problems I will do a CONFIG_DEBUG_LOCKDEP=y to see if
>>>> I get some more infos on the workqueue trouble.
>>>>
>>>> [   23.874836] BUG: sleeping function called from invalid context at
>>>> kernel/workqueue.c:2678
>>>> [   23.874902] in_atomic(): 0, irqs_disabled(): 1, pid: 1411, name: acpid
>>>
>>> Did you get a stack trace?  There are quite a few potential callers of
>>> start_flush_work() via flush_work().
>>>
>>
>> Hi Paul :-),
>>
>> Here is the stack trace.
>>
>> [   23.045871] BUG: sleeping function called from invalid context at
>> kernel/workqueue.c:2678
>> [   23.045982] in_atomic(): 0, irqs_disabled(): 1, pid: 1399, name: acpid
>> [   23.046064] 3 locks held by acpid/1399:
>> [   23.046066]  #0:  (&evdev->mutex){+.+...}, at: [<ffffffff8174ac7c>]
>> evdev_release+0xbc/0xf0
>> [   23.046081]  #1:  (&dev->mutex#2){+.+...}, at: [<ffffffff81742397>]
>> input_close_device+0x27/0x70
>> [   23.046093]  #2:  (hid_open_mut){+.+...}, at: [<ffffffffa0056388>]
>> usbhid_close+0x28/0xb0 [usbhid]
>> [   23.046106] irq event stamp: 3306
>> [   23.046109] hardirqs last  enabled at (3305): [<ffffffff8192ae32>]
>> _raw_spin_unlock_irq+0x32/0x60
>> [   23.046115] hardirqs last disabled at (3306): [<ffffffff81121017>]
>> del_timer_sync+0x37/0x110
>> [   23.046122] softirqs last  enabled at (2704): [<ffffffff818b12c9>]
>> local_bh_enable+0x9/0x20
>> [   23.046128] softirqs last disabled at (2702): [<ffffffff818b12a9>]
>> local_bh_disable+0x9/0x20
>> [   23.046136] CPU: 2 PID: 1399 Comm: acpid Not tainted
>> 4.3.0-rc3-3-llvmlinux-amd64 #1
>> [   23.046139] Hardware name: SAMSUNG ELECTRONICS CO., LTD.
>> 530U3BI/530U4BI/530U4BH/530U3BI/530U4BI/530U4BH, BIOS 13XK 03/28/2013
>> [   23.046143]  ffff8800d36ee948 0000000000000092 0000000000000000
>> ffff8800bbacfae8
>> [   23.046151]  ffffffff8149adad ffff8800bbacfb18 ffffffff810cd1ea
>> ffffffff81c56f0a
>> [   23.046158]  ffff8800c22dc400 0000000000000000 0000000000000a76
>> ffff8800bbacfb58
>> [   23.046165] Call Trace:
>> [   23.046172]  [<ffffffff8149adad>] dump_stack+0x7d/0xa0
>> [   23.046177]  [<ffffffff810cd1ea>] ___might_sleep+0x28a/0x2a0
>> [   23.046182]  [<ffffffff810cceef>] __might_sleep+0x4f/0xc0
>> [   23.046187]  [<ffffffff810afbff>] start_flush_work+0x2f/0x290
>> [   23.046192]  [<ffffffff810afbac>] flush_work+0x5c/0x80
>> [   23.046195]  [<ffffffff810afb6a>] ? flush_work+0x1a/0x80
>> [   23.046202]  [<ffffffff810eed0d>] ? trace_hardirqs_off+0xd/0x10
>> [   23.046206]  [<ffffffff810aecc8>] ? try_to_grab_pending+0x48/0x360
>> [   23.046211]  [<ffffffff8192ac53>] ? _raw_spin_lock_irqsave+0x73/0x80
>> [   23.046216]  [<ffffffff810afff9>] __cancel_work_timer+0x179/0x260
>> [   23.046221]  [<ffffffff8192add2>] ? _raw_spin_unlock_irqrestore+0x52/0x80
>> [   23.046226]  [<ffffffff81120fcd>] ? try_to_del_timer_sync+0xad/0xc0
>> [   23.046230]  [<ffffffff810afe78>] cancel_work_sync+0x18/0x20
>> [   23.046237]  [<ffffffffa00563d5>] usbhid_close+0x75/0xb0 [usbhid]
>> [   23.046245]  [<ffffffffa00394d1>] hidinput_close+0x31/0x40 [hid]
>> [   23.046251]  [<ffffffffa00394a0>] ? hidinput_open+0x40/0x40 [hid]
>> [   23.046256]  [<ffffffff817423b8>] input_close_device+0x48/0x70
>> [   23.046261]  [<ffffffff8174ac96>] evdev_release+0xd6/0xf0
>> [   23.046267]  [<ffffffff812728c7>] __fput+0x107/0x240
>> [   23.046271]  [<ffffffff81272756>] ____fput+0x16/0x20
>> [   23.046276]  [<ffffffff810b945c>] task_work_run+0x6c/0xe0
>> [   23.046282]  [<ffffffff81003aa7>] prepare_exit_to_usermode+0x117/0x120
>> [   23.046287]  [<ffffffff81003ce1>] syscall_return_slowpath+0x231/0x2a0
>> [   23.046292]  [<ffffffff8126efa5>] ? filp_close+0x65/0x90
>> [   23.046298]  [<ffffffff810ef1c9>] ? trace_hardirqs_on_caller+0x19/0x290
>> [   23.046303]  [<ffffffff81003017>] ? trace_hardirqs_on_thunk+0x17/0x19
>> [   23.046308]  [<ffffffff8192bb62>] int_ret_from_sys_call+0x25/0x9f
>>
>> Can you give help on how to "debug" this?
>>
>> I switched from full-dynticks to simple cpu-accounting which did not help.
>> But this was only a suspicion as Jiri pointed to the possibility
>> del_timer_sync() could have get some mis-optimization.
>>
>> So, more empty head here.
>>
>
> Forgot to attach dmesg-log and my kernel-config.
> Sorry about that.
>

Time for a pause!

Forgot to attach disassembled kernel/workqueue.o.

- Sedat -

Attachment: kernel-workqueue_o.txt.gz
Description: GNU Zip compressed data