On Wed, Sep 01, 2010 at 12:50:51PM +0200, Eric Dumazet wrote: > Plamen, could you test following patch ? > > I reproduced problem on a dev machine and following patch cured it. > > Thanks > > [PATCH] gro: fix different skb headrooms > > packets entering GRO might have different headrooms, even for a given > flow (because of implementation details in drivers, like copybreak). > We cant force drivers to deliver packets with a fixed headroom. > > 1) fix skb_segment() > > skb_segment() makes the false assumption headrooms of fragments are same > than the head. When CHECKSUM_PARTIAL is used, this can give csum_start > errors, and crash later in skb_copy_and_csum_dev() > > 2) allocate a minimal skb for head of frag_list > > skb_gro_receive() uses netdev_alloc_skb(headroom + skb_gro_offset(p)) to > allocate a fresh skb. This adds NET_SKB_PAD to a padding already > provided by netdevice, depending on various things, like copybreak. > > Use alloc_skb() to allocate an exact padding, to reduce cache line > needs: > NET_SKB_PAD + NET_IP_ALIGN > > bugzilla : https://bugzilla.kernel.org/show_bug.cgi?id=16626 > > Many thanks to Plamen Petrov, testing many debugging patches ! > With help of Jarek Poplawski. > > Reported-by: Plamen Petrov <pvp-lsts@xxxxxxxxxxxxxx> > Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx> > CC: Jarek Poplawski <jarkao2@xxxxxxxxx> Thanks for diagnosing and fixing this! > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 3a2513f..26396ff 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -2573,6 +2573,10 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features) > __copy_skb_header(nskb, skb); > nskb->mac_len = skb->mac_len; > > + /* nskb and skb might have different headroom */ > + if (nskb->ip_summed == CHECKSUM_PARTIAL) > + nskb->csum_start += skb_headroom(nskb) - headroom; This test is redundant since we require CHECKSUM_PARTIAL for GSO packets. Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
