From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754786Ab0IAKvS (ORCPT ); Wed, 1 Sep 2010 06:51:18 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:57391 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752155Ab0IAKvP (ORCPT ); Wed, 1 Sep 2010 06:51:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=i13kS2nb8KFu0b+9VaNl+z2F576NCuUpH9747HdPf83XQ8bv9fS7o9C6r0Sh+oBCNK svboQ4KpDcl68UU9YA+fxiS2pCYCw130/5fmmdBsBibSUsBJaeE/RP4QzHXxkop0rQ58 SY7ZM6/ZR9AwAYcuQ+Xy3X8i+sDoqkgDzLW2w= Subject: Re: [Bug #16626] Machine hangs with EIP at skb_copy_and_csum_dev From: Eric Dumazet To: Jarek Poplawski , Plamen Petrov , Herbert Xu Cc: "Rafael J. Wysocki" , Kernel Testers List , Maciej Rutecki , "David S. Miller" , Linux Kernel Mailing List , netdev@vger.kernel.org In-Reply-To: <20100831192659.GA3093@del.dom.local> References: <4LwrqITm-eJ.A.r8G.eFueMB@chimera> <4AUWBNzTkbD.A.ey.cGueMB@chimera> <20100831192659.GA3093@del.dom.local> Content-Type: text/plain; charset="UTF-8" Date: Wed, 01 Sep 2010 12:50:51 +0200 Message-ID: <1283338251.2556.124.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Signed-off-by: Eric Dumazet CC: Jarek Poplawski --- patch against linux-2.6 current tree net/core/skbuff.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) 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; + skb_reset_mac_header(nskb); skb_set_network_header(nskb, skb->mac_len); nskb->transport_header = (nskb->network_header + @@ -2702,8 +2706,8 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) } else if (skb_gro_len(p) != pinfo->gso_size) return -E2BIG; - headroom = skb_headroom(p); - nskb = netdev_alloc_skb(p->dev, headroom + skb_gro_offset(p)); + headroom = NET_SKB_PAD + NET_IP_ALIGN; + nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC); if (unlikely(!nskb)) return -ENOMEM;