Date: Fri, 10 Jan 2014 10:21:14 +0900 From: Yonghyeon PYUN <pyunyh@gmail.com> To: Alexandre Martins <alexandre.martins@netasq.com> Cc: jfv@freebsd.org, freebsd-current@freebsd.org, fabien.thomas@netasq.com, damien.deville@netasq.com Subject: Re: FreeBSD 10-RC4: Got crash in igb driver Message-ID: <20140110012114.GA3103@michelle.cdnetworks.com> In-Reply-To: <48005124.ny58tnLn4d@pc-alex> References: <48005124.ny58tnLn4d@pc-alex>
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On Thu, Jan 09, 2014 at 04:06:09PM +0100, Alexandre Martins wrote: > Dear, > > I experience some troubles with the igb device driver on FreeBSD 10-RC4. > > The kernel make a pagefault in the igb_tx_ctx_setup function when accessing to > a IPv6 header. > > The network configuration is the following: > - box acting as an IPv6 router > - one interface with an IPv6 (igb0) > - another interface with a vlan, and IPv6 on it (vlan0 on igb1) > > Vlan Hardware tagging is set on both interfaces. > > The packet that cause the crash come from igb0 and go to vlan0. > > After investigation, i see that the mbuf is split in two. The first one carry > the ethernet header, the second, the IPv6 header and data payload. > > The split is due to the "m_copy" done in ip6_forward, that make the mbuf not > writable and the "M_PREPEND" in ether_output that insert the new mbuf before > the original one. > > The kernel crashes only if the newly allocated mbuf is at the end of a memory > page, and no page is available after this one. So, it's extremly rare. > > I inserted a "KASSERT" into the function (see attached patch) to check this > behavior, and it raises on every IPv6 forwarded packet to the vlan. The > problem disapear if i remove hardware tagging. > > In the commit 256200, i see that pullups has been removed. May it be related ? > I think I introduced the header parsing code to meet controller requirement in em(4) and Jack borrowed that code in the past but it seems it was removed in r256200. It seems igb_tx_ctx_setup() assumes it can access ethernet/IP/TCP/UDP headers in the first mbuf of the chain. This looks wrong to me. > Can you confirm the problem ? > Probably Jack can tell more about change made in r256200. It's not easy for me to verify correctness of igb(4) at this moment. > Best regards > > -- > Alexandre Martins > NETASQ -- We secure IT
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