[vbox-dev] build issues of 5.0.22

[Hans-Peter Jansen]

Dear Frank,

thanks for the immediate response. Much appreciated.

On Montag, 27. Juni 2016 17:06:44 Frank Mehnert wrote:
> Peter,
> 
> On Monday 27 June 2016 16:35:26 Hans-Peter Jansen wrote:
> > 
> > I wonder, how this could creep into the distribution, but it could also be
> > related to the openSUSE build, that I based my build upon (but the applied
> > patches doesn't appear to be guilty, AFAICS).
> 
> your patch for adding '-e' to the $(SED) command is not required here
> but it's IMO more correct so I will add it to the repository.

Fine.
 
> The openSUSE patch is not necessary. Since 2.6.31 there is no need to update
> trans_start as it is done by dev_hard_start_xmit by calling the
> txq_trans_update upon device xmit callback exit.

Thanks for the explanation.
 
> > The reason to build this package myself is due to suffering from an issue
> > 
> > with 5.0.18 and a bridged nic setup, that is flooding my logs with:
> > 	VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
> > 	
> >     Last message 'VBoxNetFlt: Failed t' repeated 196 times, suppressed by
> > 
> > syslog-ng
> > 
> > That's produced from a w2k8R2 VM on a Linux 4.2.25 host. The VM seems to
> > suffer under high host load. Let's see, how 5.0.22 behaves in this
> > respect.
> > In case, this rings a bell for you, let me know.
> 
> Sorry, doesn't ring a bell.

Unfortunately, 5.0.22 doesn't fix this issue.

To give you an idea, more than 6500 packets were dropped in about two minutes:

Jun 27 23:48:05 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:46:55 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 3350 times, suppressed by syslog-ng 
Jun 27 23:48:35 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:47:25 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 1318 times, suppressed by syslog-ng 
Jun 27 23:49:05 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:47:55 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 589 times, suppressed by syslog-ng 
Jun 27 23:49:35 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:48:02 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 5 times, suppressed by syslog-ng 
Jun 27 23:49:41 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:48:32 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 622 times, suppressed by syslog-ng 
Jun 27 23:50:12 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:48:39 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 140 times, suppressed by syslog-ng 
Jun 27 23:50:18 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:49:08 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 377 times, suppressed by syslog-ng 
Jun 27 23:50:47 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:49:38 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 1291 times, suppressed by syslog-ng 
Jun 27 23:51:18 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:50:08 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 29 times, suppressed by syslog-ng 
Jun 27 23:51:49 server kernel: VBoxNetFlt: Failed to allocate packet buffer, dropping the packet.
Jun 27 23:50:10 server kernel: Last message 'VBoxNetFlt: Failed t' repeated 5 times, suppressed by syslog-ng

Hmm, reading the source reveals, that this code path is only exercised, if 
VBOXNETFLT_SG_SUPPORT is not defined. Bears the questions, why does skb_copy fails
this often and/or is VBoxNetFlt-linux.c able to deal with fragmented packets, which
would avoid this copying (other than making vbox VLAN support dysfunctional).

Pete