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

From: Sedat Dilek
Date: Sun Sep 27 2015 - 13:24:27 EST

On Sun, Sep 27, 2015 at 6:42 PM, Paul E. McKenney
<paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> On Sun, Sep 27, 2015 at 05:55:43PM +0200, Sedat Dilek 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 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.
>
> I am not familiar with the "hardirqs last enabled" debug output, but
> I am guessing that hardirqs are disabled because the "last disabled"
> number is greater than the "last enabled" number. So if I understand
> correctly, something somewhere up the call stack has irqs disabled,
> but is calling a function that needs them enabled.
>
> A quick look at usbhid_close() shows no problem, but then again, I am
> looking at the v4.2 version rather than whatever you are testing.
> But v4.3-rc2 looks the same.
>
> Looks like you are already in contact with Jiri, which is good.
>
> Another thing to try would be to insert might_sleep() calls, after
> usbhid_close(), since it enables irqs explicitly, but before the call
> to flush_work(). Jiri's comment can be interpreted as a suggestion
> to insert a might_sleep() in try_to_del_timer_sync(), though
> __cancel_work_timer() wouldn't be a bad place to try as well,
> just before its call to flush_work().

With...

--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1026,6 +1026,8 @@ int try_to_del_timer_sync(struct timer_list *timer)
unsigned long flags;
int ret = -1;

+ might_sleep();
+
debug_assert_init(timer);

base = lock_timer_base(timer, &flags);

...I get now...

[ 53.104411] BUG: sleeping function called from invalid context at
kernel/time/timer.c:1029
[ 53.104417] in_atomic(): 0, irqs_disabled(): 1, pid: 2100, name: fusermount
[ 53.104419] 1 lock held by fusermount/2100:
[ 53.104420] #0: (&type->s_umount_key#33){+.+...}, at:
[<ffffffff812746ab>] deactivate_super+0x5b/0x70
[ 53.104432] irq event stamp: 3734
[ 53.104433] hardirqs last enabled at (3733): [<ffffffff810aefb8>]
mod_delayed_work_on+0x78/0xa0
[ 53.104438] hardirqs last disabled at (3734): [<ffffffff810b045f>]
flush_delayed_work+0x1f/0x70
[ 53.104441] softirqs last enabled at (3730): [<ffffffff81204997>]
wb_shutdown+0x47/0xb0
[ 53.104444] softirqs last disabled at (3728): [<ffffffff81204976>]
wb_shutdown+0x26/0xb0
[ 53.104449] CPU: 3 PID: 2100 Comm: fusermount Not tainted
4.3.0-rc3-4-llvmlinux-amd64 #2
[ 53.104451] Hardware name: SAMSUNG ELECTRONICS CO., LTD.
530U3BI/530U4BI/530U4BH/530U3BI/530U4BI/530U4BH, BIOS 13XK 03/28/2013
[ 53.104453] 000000000000000a 0000000000000096 0000000000000000
ffff8800af39bb28
[ 53.104457] ffffffff8149cadd ffff8800af39bb58 ffffffff810cd5aa
ffffffff81c5f2e8
[ 53.104461] ffff8800c5785940 0000000000000000 0000000000000405
ffff8800af39bb98
[ 53.104465] Call Trace:
[ 53.104470] [<ffffffff8149cadd>] dump_stack+0x7d/0xa0
[ 53.104473] [<ffffffff810cd5aa>] ___might_sleep+0x28a/0x2a0
[ 53.104475] [<ffffffff810cd2af>] __might_sleep+0x4f/0xc0
[ 53.104480] [<ffffffff81122055>] try_to_del_timer_sync+0x25/0xe0
[ 53.104483] [<ffffffff81122204>] del_timer_sync+0xf4/0x110
[ 53.104486] [<ffffffff8112214b>] ? del_timer_sync+0x3b/0x110
[ 53.104497] [<ffffffff810b0468>] flush_delayed_work+0x28/0x70
[ 53.104499] [<ffffffff812049cb>] wb_shutdown+0x7b/0xb0
[ 53.104501] [<ffffffff812046fd>] bdi_destroy+0x7d/0x2d0
[ 53.104505] [<ffffffff810efe2d>] ? trace_hardirqs_on+0xd/0x10
[ 53.104509] [<ffffffff813b7b08>] fuse_put_super+0xf8/0x140
[ 53.104511] [<ffffffff813b7a10>] ? fuse_evict_inode+0x80/0x80
[ 53.104513] [<ffffffff81274778>] generic_shutdown_super+0x68/0x120
[ 53.104515] [<ffffffff81275a80>] kill_anon_super+0x20/0x70
[ 53.104518] [<ffffffff813b6fcd>] fuse_kill_sb_anon+0x4d/0x60
[ 53.104520] [<ffffffff812745dd>] deactivate_locked_super+0x4d/0xc0
[ 53.104522] [<ffffffff812746b3>] deactivate_super+0x63/0x70
[ 53.104525] [<ffffffff8129fa02>] cleanup_mnt+0xb2/0x140
[ 53.104528] [<ffffffff8129f93a>] __cleanup_mnt+0x1a/0x30
[ 53.104531] [<ffffffff810b97bc>] task_work_run+0x6c/0xe0
[ 53.104534] [<ffffffff81003b8a>] prepare_exit_to_usermode+0x13a/0x140
[ 53.104537] [<ffffffff81003e11>] syscall_return_slowpath+0x281/0x2f0
[ 53.104540] [<ffffffff8129c121>] ? SyS_umount+0x341/0x620
[ 53.104542] [<ffffffff810f02d9>] ? trace_hardirqs_on_caller+0x19/0x290
[ 53.104545] [<ffffffff81003017>] ? trace_hardirqs_on_thunk+0x17/0x19
[ 53.104550] [<ffffffff8192da22>] int_ret_from_sys_call+0x25/0x9f

A problem in fuse?

- Sedat -

>
> Thanx, Paul
>
>> - Sedat -
>>
>> >> $ grep LOCKDEP /boot/config-4.3.0-rc2-438.1-llvmlinux-amd64
>> >> CONFIG_LOCKDEP_SUPPORT=y
>> >> CONFIG_LOCKDEP=y
>> >> # CONFIG_DEBUG_LOCKDEP is not set
>> >>
>> >> So, CLANG is a bit different compiler :-).
>> >
>> > True enough. Good to have more than one, though.
>> >
>> > Thanx, Paul
>> >
>> >> Thanks for taking care.
>> >>
>> >> Regards,
>> >> - Sedat -
>> >>
>> >> >>
>> >> >> [1] http://marc.info/?l=linux-kernel&m=144332758307978&w=2
>> >> >> [2] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/patch/?id=66e8c57da6bf6b847a48a5a6fda59512f733ed78
>> >> >> [3] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/patch/?id=19a5ecde086a6a5287978b12ae948fa691b197b7
>> >> >>
>> >> >
>> >>
>> >
>>
>
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