[Intel-wired-lan] Linux 4.12+ memory leak on router with i40e NICs

[Anders K. Pedersen | Cohaesio]

On ons, 2017-10-04 at 08:32 -0700, Alexander Duyck wrote:
> On Wed, Oct 4, 2017 at 5:56 AM, Anders K. Pedersen | Cohaesio
> <akp at cohaesio.com> wrote:
> > Hello,
> > 
> > After updating one of our Linux based routers to kernel 4.13 it
> > began
> > leaking memory quite fast (about 1 GB every half hour). To narrow
> > we
> > tried various kernel versions and found that 4.11.12 is okay, while
> > 4.12 also leaks, so we did a bisection between 4.11 and 4.12.
> > 
> > The first bisection ended at
> > "[6964e53f55837b0c49ed60d36656d2e0ee4fc27b] i40e: fix handling of
> > HW
> > ATR eviction", which fixes some flag handling that was broken by
> > 47994c119a36 "i40e: remove hw_disabled_flags in favor of using
> > separate
> > flag bits", so I did a second bisection, where I added 6964e53f5583
> > "i40e: fix handling of HW ATR eviction" to the steps that had
> > 47994c119a36 "i40e: remove hw_disabled_flags in favor of using
> > separate
> > flag bits" in them.
> > 
> > The second bisection ended at
> > "[0e626ff7ccbfc43c6cc4aeea611c40b899682382] i40e: Fix support for
> > flow
> > director programming status", where I don't see any obvious
> > problems,
> > so I'm hoping for some assistance.
> > 
> > The router is a PowerEdge R730 server (Haswell based) with three
> > Intel
> > NICs (all using the i40e driver):
> > 
> > X710 quad port 10 GbE SFP+: eth0 eth1 eth2 eth3
> > X710 quad port 10 GbE SFP+: eth4 eth5 eth6 eth7
> > XL710 dual port 40 GbE QSFP+: eth8 eth9
> > 
> > The NICs are aggregated with LACP with the team driver:
> > 
> > team0: eth9 (40 GbE selected primary), and eth3, eth7 (10 GbE non-
> > selected backups)
> > team1: eth0, eth1, eth4, eth5 (all 10 GbE selected)
> > 
> > team0 is used for internal networks and has one untagged and four
> > tagged VLAN interfaces, while team1 has an external uplink
> > connection
> > without any VLANs.
> > 
> > The router runs an eBGP session on team1 to one of our uplinks, and
> > iBGP via team0 to our other border routers. It also runs OSPF on
> > the
> > internal VLANs on team0. One thing I've noticed is that when OSPF
> > is
> > not announcing a default gateway to the internal networks, so there
> > is
> > almost no traffic coming in on team0 and out on team1, but still
> > plenty
> > of traffic coming in on team1 and out via team0, there's no memory
> > leak
> > (or at least it is so small that we haven't detected it). But as
> > soon
> > as we configure OSPF to announce a default gateway to the internal
> > VLANs, so we get traffic from team0 to team1 the leaking begins.
> > Stopping the OSPF default gateway announcement again also stops the
> > leaking, but does not release already leaked memory.
> > 
> > So this leads to me suspect that the leaking is related to RX on
> > team0
> > (where XL710 eth9 is normally the only active interface) or TX on
> > team1
> > (X710 eth0, eth1, eth4, eth5). The first bad commit is related to
> > RX
> > cleaning, which suggests RX on team0. Since we're only seeing the
> > leak
> > for our outbound traffic, I suspect either a difference between the
> > X710 vs. XL710 NICs, or that the inbound traffic is for relatively
> > few
> > destination addresses (only our own systems) while the outbound
> > traffic
> > is for many different addresses on the internet. But I'm just
> > guessing
> > here.
> > 
> > I've tried kmemleak, but it only found a few kB of suspected memory
> > leaks (several of which disappeared again after a while).
> > 
> > Below I've included more details - git bisect logs, ethtool -i,
> > dmesg,
> > Kernel .config, and various memory related /proc files. Any help or
> > suggestions would be much appreciated, and please let me know if
> > more
> > information is needed or there's something I should try.
> > 
> > Regards,
> > Anders K. Pedersen
> > 
> 
> Hi Anders,
> 
> I think I see the problem and should have a patch submitted shortly
> to
> address it. From what I can tell it looks like the issue is that we
> weren't properly recycling the pages associated with descriptors that
> contained an Rx programming status. For now the workaround would be
> to
> try disabling ATR via the "ethtool --set-priv-flags" command. I
> should
> have a patch out in the next hour or so that you can try testing to
> verify if it addresses the issue.
> 
> Thanks.
> 
> - Alex

Thanks Alex,

I will test the patch in our next service window on Tuesday morning.

Regards,
Anders