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Subject: Re: Urgent: BUG: PPP ioctl Transport endpoint is not connected
From:   Martin Zaharinov <micron10@gmail.com>
In-Reply-To: <20201209164013.GA21199@linux.home>
Date:   Wed, 9 Dec 2020 18:57:44 +0200
Cc:     "linux-kernel@vger kernel. org" <linux-kernel@vger.kernel.org>,
        Eric Dumazet <eric.dumazet@gmail.com>, netdev@vger.kernel.org
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 <20201209164013.GA21199@linux.home>
To:     Guillaume Nault <gnault@redhat.com>
Precedence: bulk

Hi Nault=20


> On 9 Dec 2020, at 18:40, Guillaume Nault <gnault@redhat.com> wrote:
>=20
> On Wed, Dec 09, 2020 at 04:47:52PM +0200, Martin Zaharinov wrote:
>> Hi All
>>=20
>> I have problem with latest kernel release=20
>> And the problem is base on this late problem :
>>=20
>>=20
>> =
https://www.mail-archive.com/search?l=3Dnetdev@vger.kernel.org&q=3Dsubject=
:%22Re%5C%3A+ppp%5C%2Fpppoe%2C+still+panic+4.15.3+in+ppp_push%22&o=3Dnewes=
t&f=3D1
>>=20
>> I have same problem in kernel 5.6 > now I use kernel 5.9.13 and have =
same problem.
>>=20
>>=20
>> In kernel 5.9.13 now don=E2=80=99t have any crashes in dimes but in =
one moment accel service stop with defunct and in log have many of this =
line :
>>=20
>>=20
>> error: vlan608: ioctl(PPPIOCCONNECT): Transport endpoint is not =
connected
>> error: vlan617: ioctl(PPPIOCCONNECT): Transport endpoint is not =
connected
>> error: vlan679: ioctl(PPPIOCCONNECT): Transport endpoint is not =
connected
>>=20
>> In one moment connected user bump double or triple and after that =
service defunct and need wait to drop all session to start .
>>=20
>> I talk with accel-ppp team and they said this is kernel related =
problem and to back to kernel 4.14 there is not this problem.
>>=20
>> Problem is come after kernel 4.15 > and not have solution to this =
moment.
>=20
> I'm sorry, I don't understand.
> Do you mean that v4.14 worked fine (no crash, no ioctl() error)?
> Did the problem start appearing in v4.15? Or did v4.15 work and the
> problem appeared in v4.16?

In Telegram group I talk with Sergey and Dimka and told my the problem =
is come after changes from 4.14 to 4.15=20
Sergey write this : "as I know, there was a similar issue in kernel 4.15 =
so maybe it is still not fixed=E2=80=9D

I don=E2=80=99t have options to test with this old kernel 4.14.xxx i =
don=E2=80=99t have support for them.


>=20
>> Please help to find the problem.
>>=20
>> Last time in link I see is make changes in ppp_generic.c=20
>>=20
>> ppp_lock(ppp);
>>        spin_lock_bh(&pch->downl);
>>        if (!pch->chan) {
>>                /* Don't connect unregistered channels */
>>                spin_unlock_bh(&pch->downl);
>>                ppp_unlock(ppp);
>>                ret =3D -ENOTCONN;
>>                goto outl;
>>        }
>>        spin_unlock_bh(&pch->downl);
>>=20
>>=20
>> But this fix only to don=E2=80=99t display error and freeze system=20
>> The problem is stay and is to big.
>=20
> Do you use accel-ppp's unit-cache option? Does the problem go away if
> you stop using it?
>=20

No I don=E2=80=99t use unit-cache , if I set unit-cache accel-ppp =
defunct same but user Is connect and disconnet more fast.

The problem is same with unit and without .=20
Only after this patch I don=E2=80=99t see error in dimes but this is not =
solution.
In network have customer what have power cut problem, when drop 600 user =
and back Is normal but in this moment kernel is locking and start to =
make this :=20
sessions:
  starting: 4235
  active: 3882
  finishing: 378

 The problem is starting session is not real user normal user in this =
server is ~4k customers .

I use pppd_compat .

Any idea ?

>>=20
>> Please help to fix.
Martin