2.4.0-pre3+zerocopy: weird messages

2.4.0-pre3+zerocopy: weird messages

[Petru Paler]

I get messages in syslog looking like:

Undo loss 192.147.174.183/59953 c2 l0 ss2/65535 p0
Undo loss 63.148.232.53/4423 c2 l0 ss2/2 p0
Undo loss 204.253.105.63/25 c2 l0 ss2/2 p0                                                

This is on a dual UltraSPARC box with a Happy Meal network
card. I don't think either Postfix or tinydns (the main load) are using
sendfile().

The machine is stable so far, but it's been up for only 15 minutes.

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Petru Paler, mailto:ppetru@ppetru.net
http://www.ppetru.net - ICQ: 41817235
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Re: 2.4.0-pre3+zerocopy: weird messages

[David S. Miller]

Petru Paler writes:
 > I get messages in syslog looking like:
 > 
 > Undo loss 192.147.174.183/59953 c2 l0 ss2/65535 p0
 > Undo loss 63.148.232.53/4423 c2 l0 ss2/2 p0
 > Undo loss 204.253.105.63/25 c2 l0 ss2/2 p0

These are normal, if they annoy you please change FASTRETRANS_DEBUG
back to "1" in include/net/tcp.h

This is just an increased debugging setting compared to Linus's
tree, the message you see is harmless.

Later,
David S. Miller
davem@redhat.com
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Re: 2.4.0-pre3+zerocopy: weird messages

[Petru Paler]

On Sun, Jan 14, 2001 at 02:33:26AM -0800, David S. Miller wrote:
> Petru Paler writes:
>  > I get messages in syslog looking like:
>  > 
>  > Undo loss 192.147.174.183/59953 c2 l0 ss2/65535 p0
>  > Undo loss 63.148.232.53/4423 c2 l0 ss2/2 p0
>  > Undo loss 204.253.105.63/25 c2 l0 ss2/2 p0
> 
> These are normal, if they annoy you please change FASTRETRANS_DEBUG
> back to "1" in include/net/tcp.h
> 
> This is just an increased debugging setting compared to Linus's
> tree, the message you see is harmless.

Ok. Should I keep reporting new syslog messages as they appear ? This
machine has lots of traffic, both TCP (SMTP) and UDP (DNS). Since the
last email I also got (minus the "Undo loss" ones, and I only included one
of each message types, as they repeat):

Undo partial loss 193.230.129.57/33659 c1 l5 ss2/3 p5

udp v4 hw csum failure.                                                                   

Disorder0 3 5 f0 s1 rr1                                                                   

Undo Hoe 203.162.5.28/25 c8 l1 ss5/65535 p8                                               

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Re: 2.4.0-pre3+zerocopy: weird messages

[David S. Miller]

Petru Paler writes:
 > Ok. Should I keep reporting new syslog messages as they appear ?

Not the "Undo ***" and "Disorder ***" ones".

But this one is curious:

 > udp v4 hw csum failure.                                                                   
Oh, I think I know why this happens.  Can you add this patch, and next
time the UDP bad csum message appears, tell me if it says "UDP packet
with bad csum was fragmented." in the next line of your syslog
messages?  Thanks.

Later,
David S. Miller
davem@redhat.com
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Re: 2.4.0-pre3+zerocopy: weird messages

[Petru Paler]

On Sun, Jan 14, 2001 at 02:58:54AM -0800, David S. Miller wrote:
> Petru Paler writes:
>  > Ok. Should I keep reporting new syslog messages as they appear ?
> 
> Not the "Undo ***" and "Disorder ***" ones".

Ok.

> But this one is curious:
> 
>  > udp v4 hw csum failure.                                                                   
> Oh, I think I know why this happens.  Can you add this patch, and next
> time the UDP bad csum message appears, tell me if it says "UDP packet
> with bad csum was fragmented." in the next line of your syslog
> messages?  Thanks.

Sure, but I also need the actual patch :)

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Petru Paler, mailto:ppetru@ppetru.net
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Re: 2.4.0-pre3+zerocopy: weird messages

[David S. Miller]

Petru Paler writes:
 > > Oh, I think I know why this happens.  Can you add this patch, and next
 > > time the UDP bad csum message appears, tell me if it says "UDP packet
 > > with bad csum was fragmented." in the next line of your syslog
 > > messages?  Thanks.
 > 
 > Sure, but I also need the actual patch :)

Duh, here it is :-)

--- net/ipv4/udp.c.~1~	Thu Jan 11 10:20:40 2001
+++ net/ipv4/udp.c	Sun Jan 14 02:58:07 2001
@@ -855,6 +855,8 @@
 		if (!udp_check(uh, ulen, saddr, daddr, skb->csum))
 			return 0;
 		NETDEBUG(printk(KERN_DEBUG "udp v4 hw csum failure.\n"));
+		if (skb_shinfo(skb)->frag_list != NULL)
+			printk(KERN_DEBUG "UDP packet with bad csum was fragmented.\n");
 		skb->ip_summed = CHECKSUM_NONE;
 	}
 	if (skb->ip_summed != CHECKSUM_UNNECESSARY)
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Re: 2.4.0-pre3+zerocopy: weird messages

[Petru Paler]

On Sun, Jan 14, 2001 at 03:32:40AM -0800, David S. Miller wrote:
> Petru Paler writes:
>  > > Oh, I think I know why this happens.  Can you add this patch, and next
>  > > time the UDP bad csum message appears, tell me if it says "UDP packet
>  > > with bad csum was fragmented." in the next line of your syslog
>  > > messages?  Thanks.

Jan 14 06:54:08 grey kernel: Undo loss 193.230.129.57/34342 c2 l0 ss2/2 p0
Jan 14 06:56:40 grey kernel: udp v4 hw csum failure.
Jan 14 06:57:05 grey kernel: Undo partial loss 193.230.129.57/34342 c1 l5 ss2/3 p5        

So no "UDP packet with bad csum was fragmented" line. This is the first
one though, will let you know if the fragmented thing occurs.

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Petru Paler, mailto:ppetru@ppetru.net
http://www.ppetru.net - ICQ: 41817235
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Re: 2.4.0-pre3+zerocopy: weird messages

[Petru Paler]

On Sun, Jan 14, 2001 at 02:10:03PM +0200, Petru Paler wrote:
> On Sun, Jan 14, 2001 at 03:32:40AM -0800, David S. Miller wrote:
> > Petru Paler writes:
> >  > > Oh, I think I know why this happens.  Can you add this patch, and next
> >  > > time the UDP bad csum message appears, tell me if it says "UDP packet
> >  > > with bad csum was fragmented." in the next line of your syslog
> >  > > messages?  Thanks.
> 
> Jan 14 06:54:08 grey kernel: Undo loss 193.230.129.57/34342 c2 l0 ss2/2 p0
> Jan 14 06:56:40 grey kernel: udp v4 hw csum failure.
> Jan 14 06:57:05 grey kernel: Undo partial loss 193.230.129.57/34342 c1 l5 ss2/3 p5        
> 
> So no "UDP packet with bad csum was fragmented" line. This is the first
> one though, will let you know if the fragmented thing occurs.

Got more "udp v4 hw csum failure" messages but still no "UDP packet with bad csum was fragmented".

--
Petru Paler, mailto:ppetru@ppetru.net
http://www.ppetru.net - ICQ: 41817235
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Re: 2.4.0-pre3+zerocopy: weird messages

[David S. Miller]

Petru Paler writes:
 > Got more "udp v4 hw csum failure" messages but still no "UDP packet
 > with bad csum was fragmented".

OK, last experiment :-)  Add this patch, and watch to see if
the UDP "InErrors" field in /proc/net/snmp has a non-zero value after
letting it run for a while.  Thanks.

--- drivers/net/sunhme.c.~1~	Wed Dec 13 10:31:46 2000
+++ drivers/net/sunhme.c	Sun Jan 14 05:19:09 2001
@@ -2109,11 +2109,11 @@
 
 			skb = copy_skb;
 		}
-
+#if 0
 		/* This card is _fucking_ hot... */
 		skb->csum = (csum ^ 0xffff);
 		skb->ip_summed = CHECKSUM_HW;
-
+#endif
 		RXD(("len=%d csum=%4x]", len, csum));
 		skb->protocol = eth_type_trans(skb, dev);
 		netif_rx(skb);
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Re: 2.4.0-pre3+zerocopy: weird messages

[Petru Paler]

On Sun, Jan 14, 2001 at 05:21:33AM -0800, David S. Miller wrote:
> Petru Paler writes:
>  > Got more "udp v4 hw csum failure" messages but still no "UDP packet
>  > with bad csum was fragmented".
> 
> OK, last experiment :-)  Add this patch, and watch to see if
> the UDP "InErrors" field in /proc/net/snmp has a non-zero value after
> letting it run for a while.  Thanks.

Ok, will do.

In the mean time, the box locked up hard. The last message in syslog
was:

Jan 14 10:14:45 grey kernel: Undo loss 194.67.160.18/3103 c2 l0 ss2/65535 p0              

I'm not sure when it died, and I also could not check the console (the
server is on the other side of the planet for me :).

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Petru Paler, mailto:ppetru@ppetru.net
http://www.ppetru.net - ICQ: 41817235
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Re: 2.4.0-pre3+zerocopy: weird messages

[Petru Paler]

On Sun, Jan 14, 2001 at 05:21:33AM -0800, David S. Miller wrote:
> Petru Paler writes:
>  > Got more "udp v4 hw csum failure" messages but still no "UDP packet
>  > with bad csum was fragmented".
> 
> OK, last experiment :-)  Add this patch, and watch to see if
> the UDP "InErrors" field in /proc/net/snmp has a non-zero value after
> letting it run for a while.  Thanks.

Ok, here it is:

grey:/proc/net# uptime
 12:14am  up 11:01,  1 user,  load average: 0.45, 0.47, 0.41
grey:/proc/net# cat snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails FragOKs FragFails FragCreates
Ip: 2 64 8340770 0 0 0 0 8 8290517 1359445 6 0 0 0 0 0 0 0 0
Icmp: InMsgs InErrors InDestUnreachs InTimeExcds InParmProbs InSrcQuenchs InRedirects InEchos InEchoReps InTimestamps InTimestampReps InAddrMasks InAddrMaskReps OutMsgs OutErrors OutDestUnreachs OutTimeExcds OutParmProbs OutSrcQuenchs OutRedirects OutEchos OutEchoReps OutTimestamps OutTimestampReps OutAddrMasks OutAddrMaskReps
Icmp: 7370 446 3846 772 0 39 0 2708 0 0 0 0 0 9661 0 6953 0 0 0 0 0 2708 0 0 0 0
Tcp: RtoAlgorithm RtoMin RtoMax MaxConn ActiveOpens PassiveOpens AttemptFails EstabResets CurrEstab InSegs OutSegs RetransSegs InErrs OutRsts
Tcp: 0 0 0 0 16025 0 128 0 20 825925 921717 44521 189 28300
Udp: InDatagrams NoPorts InErrors OutDatagrams
Udp: 7500511 6953 30 428614

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Petru Paler, mailto:ppetru@ppetru.net
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