Re: kernel BUG at drivers/net/xen-netback/netback.c:540!

[Atom2 <ariel.atom2@web2web.at>]

Am 12.06.14 10:41, schrieb Ian Campbell:
> On Thu, 2014-06-12 at 01:05 +0200, Atom2 wrote:
>> Hi guys,
>> I just updated my kernel version for dom0 from 3.13.10 to 3.14.5 (both
>> gentoo hardened sources) when one of my virtual machines still running
>> on 3.13.10 suddenly froze. At that time I was about to update the kernel
>> for my domU when it froze. My XEN version is 4.3.2.
>
> Looks to be the same as
> http://lists.xen.org/archives/html/xen-devel/2014-06/msg01307.html
> for which Zoltan referred to:
> http://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/drivers/net/xen-netback?id=59ae9fc67007da8b5aea7b0a31c3607745cfbfee
>
Thanks Ian for your quick reply. The issue does indeed look similar on 
the face of it (alos given that I also do use an NFS mounted filesystem 
that was accessed at the time the problem occured). Unfortunately the 
patch seems to be for 3.15 only as it does not apply to my 3.14.5 
kernel. The error messages read as follows:

patching file drivers/net/xen-netback/netback.c
Hunk #1 succeeded at 164 (offset 1 line).
Hunk #2 succeeded at 177 (offset 1 line).
Hunk #3 succeeded at 188 (offset 1 line).
Hunk #4 succeeded at 197 (offset 1 line).
Hunk #5 succeeded at 233 (offset 1 line).
Hunk #6 succeeded at 272 (offset -1 lines).
Hunk #7 FAILED at 556.
Hunk #8 succeeded at 526 (offset -91 lines).
1 out of 8 hunks FAILED -- saving rejects to file 
drivers/net/xen-netback/netback.c.rej

Hunk #7 refers to the following piece of code in the patch:
@@ -541,12 +556,6 @@ static void xenvif_add_frag_responses(struct xenvif 
*vif, int status,
         }
  }

-struct xenvif_rx_cb {
-       int meta_slots_used;
-};
-
-#define XENVIF_RX_CB(skb) ((struct xenvif_rx_cb *)(skb)->cb)
-
  void xenvif_kick_thread(struct xenvif *vif)
  {
         wake_up(&vif->wq);


Now in my kernel sources after the function xenvif_add_frag_responses 
referred to by the patch there's neither a definition of a
struct xenvif_rx_cb { ...
nor a line reading
#define XENVIF_RX_CB ...
(both of which the patch tries to remove)

but rather the definition of a
struct skb_cb_overlay {
	int meta_slots_used;
};
(which obviously the patch does not expect to see there)

I guess I'd therefore need a slightly modified patch for the 3.14.5 
kernel sources to make it compile.

Many thanks in advance,
Atom2