linux-kernel - Re: Urgent: BUG: PPP ioctl Transport endpoint is not connected

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Message-ID: <20201209164013.GA21199@linux.home>
Date:   Wed, 9 Dec 2020 17:40:13 +0100
From:   Guillaume Nault <gnault@...hat.com>
To:     Martin Zaharinov <micron10@...il.com>
Cc:     "linux-kernel@...r kernel. org" <linux-kernel@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org
Subject: Re: Urgent: BUG: PPP ioctl Transport endpoint is not connected

On Wed, Dec 09, 2020 at 04:47:52PM +0200, Martin Zaharinov wrote:
> Hi All
> 
> I have problem with latest kernel release 
> And the problem is base on this late problem :
> 
> 
> https://www.mail-archive.com/search?l=netdev@vger.kernel.org&q=subject:%22Re%5C%3A+ppp%5C%2Fpppoe%2C+still+panic+4.15.3+in+ppp_push%22&o=newest&f=1
> 
> I have same problem in kernel 5.6 > now I use kernel 5.9.13 and have same problem.
> 
> 
> In kernel 5.9.13 now don’t have any crashes in dimes but in one moment accel service stop with defunct and in log have many of this line :
> 
> 
> 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
> 
> In one moment connected user bump double or triple and after that service defunct and need wait to drop all session to start .
> 
> 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.
> 
> Problem is come after kernel 4.15 > and not have solution to this moment.

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?

> Please help to find the problem.
> 
> Last time in link I see is make changes in ppp_generic.c 
> 
> 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 = -ENOTCONN;
>                 goto outl;
>         }
>         spin_unlock_bh(&pch->downl);
> 
> 
> But this fix only to don’t display error and freeze system 
> The problem is stay and is to big.

Do you use accel-ppp's unit-cache option? Does the problem go away if
you stop using it?

> 
> Please help to fix.
> 
> 
>