netdev - Re: Urgent Bug report: PPPoE ioctl(PPPIOCCONNECT): Transport endpoint is not connected

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Date:   Tue, 7 Sep 2021 09:16:16 +0300
From:   Martin Zaharinov <micron10@...il.com>
To:     Guillaume Nault <gnault@...hat.com>
Cc:     Pali Rohár <pali@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: Urgent  Bug report: PPPoE ioctl(PPPIOCCONNECT): Transport
 endpoint is not connected

Hi 
Sorry for delay but not easy to catch moment .


See this is mpstatl 1 :

Linux 5.14.1 (demobng) 	09/07/21 	_x86_64_	(12 CPU)

11:12:16     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
11:12:17     all    0.17    0.00    6.66    0.00    0.00    4.13    0.00    0.00    0.00   89.05
11:12:18     all    0.25    0.00    8.36    0.00    0.00    4.88    0.00    0.00    0.00   86.51
11:12:19     all    0.26    0.00    9.62    0.00    0.00    3.91    0.00    0.00    0.00   86.21
11:12:20     all    0.85    0.00    6.00    0.00    0.00    4.31    0.00    0.00    0.00   88.84
11:12:21     all    0.08    0.00    4.45    0.00    0.00    4.79    0.00    0.00    0.00   90.67
11:12:22     all    0.17    0.00    9.50    0.00    0.00    4.58    0.00    0.00    0.00   85.75
11:12:23     all    0.00    0.00    6.92    0.00    0.00    2.48    0.00    0.00    0.00   90.61
11:12:24     all    0.17    0.00    5.45    0.00    0.00    4.27    0.00    0.00    0.00   90.11
11:12:25     all    0.25    0.00    5.38    0.00    0.00    4.79    0.00    0.00    0.00   89.58
11:12:26     all    0.60    0.00    1.45    0.00    0.00    2.65    0.00    0.00    0.00   95.30
11:12:27     all    0.42    0.00    6.91    0.00    0.00    4.47    0.00    0.00    0.00   88.20
11:12:28     all    0.00    0.00    6.75    0.00    0.00    4.18    0.00    0.00    0.00   89.07
11:12:29     all    0.17    0.00    3.52    0.00    0.00    5.11    0.00    0.00    0.00   91.20
11:12:30     all    1.45    0.00   10.14    0.00    0.00    3.49    0.00    0.00    0.00   84.92
11:12:31     all    0.09    0.00    5.11    0.00    0.00    4.77    0.00    0.00    0.00   90.03
11:12:32     all    0.25    0.00    3.11    0.00    0.00    4.46    0.00    0.00    0.00   92.17
Average:     all    0.32    0.00    6.21    0.00    0.00    4.21    0.00    0.00    0.00   89.26


I attache and one screenshot from perf top (Screenshot is send on preview mail)

And I see in lsmod 

pppoe                  20480  8198
pppox                  16384  1 pppoe
ppp_generic            45056  16364 pppox,pppoe
slhc                   16384  1 ppp_generic

To slow remove pppoe session .

And from log : 

[2021-09-07 11:01:11.129] vlan3020: ebdd1c5d8b5900f6: ioctl(PPPIOCCONNECT): Transport endpoint is not connected
[2021-09-07 11:01:53.621] vlan643: ebdd1c5d8b59014e: ioctl(PPPIOCCONNECT): Transport endpoint is not connected
[2021-09-07 11:02:00.359] vlan1616: ebdd1c5d8b590195: ioctl(PPPIOCCONNECT): Transport endpoint is not connected
[2021-09-07 11:02:05.859] vlan3020: ebdd1c5d8b5900d8: ioctl(PPPIOCCONNECT): Transport endpoint is not connected
[2021-09-07 11:02:08.258] vlan3005: ebdd1c5d8b590190: ioctl(PPPIOCCONNECT): Transport endpoint is not connected
[2021-09-07 11:02:13.820] vlan643: ebdd1c5d8b590152: ioctl(PPPIOCCONNECT): Transport endpoint is not connected
[2021-09-07 11:02:15.839] vlan727: ebdd1c5d8b590144: ioctl(PPPIOCCONNECT): Transport endpoint is not connected
[2021-09-07 11:02:20.139] vlan1693: ebdd1c5d8b59019f: ioctl(PPPIOCCONNECT): Transport endpoint is not connected

> On 11 Aug 2021, at 19:48, Guillaume Nault <gnault@...hat.com> wrote:
> 
> On Wed, Aug 11, 2021 at 02:10:32PM +0300, Martin Zaharinov wrote:
>> And one more that see.
>> 
>> Problem is come when accel start finishing sessions,
>> Now in server have 2k users and restart on one of vlans 3 Olt with 400 users and affect other vlans ,
>> And problem is start when start destroying dead sessions from vlan with 3 Olt and this affect all other vlans.
>> May be kernel destroy old session slow and entrained other users by locking other sessions.
>> is there a way to speed up the closing of stopped/dead sessions.
> 
> What are the CPU stats when that happen? Is it users space or kernel
> space that keeps it busy?
> 
> One easy way to check is to run "mpstat 1" for a few seconds when the
> problem occurs.
>