Re: What is "recvmsg bug: copied 870A11AD seq 0"? (2.2.19)

From: Bernd Jendrissek (berndj@prism.co.za)
Date: Mon Oct 14 2002 - 09:11:41 EST


On Mon, Oct 14, 2002 at 11:16:05PM +1000, James Morris wrote:
> On Mon, 14 Oct 2002, Bernd Jendrissek wrote:
>
> > Hello all
> >
> > What does it mean if the last 9 items in dmesg from a 2.2.19 kernel say
> > "recvmsg bug: copied 870A11AD seq 0"? Same sequence number each time.
> >
> > A kernel (known) bug? Some bogus TCP segments?
>
> It's been reported a few times, but I'm not sure if it's been resolved.
>
> Can you please post the version of the compiler which compiled the kernel,
> what kind of hardware you're running on, and if it's a stock kernel or has
> vendor/other patches applied.

$ cat /proc/version
Linux version 2.2.19 (berndj@penguin.wetton.prism.co.za) (gcc version egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)) #2 Wed Aug 1 13:51:15 SAST 2001

$ lspci
00:00.0 Host bridge: Intel Corporation 440BX/ZX - 82443BX/ZX Host bridge (rev 03)
00:01.0 PCI bridge: Intel Corporation 440BX/ZX - 82443BX/ZX AGP bridge (rev 03)
00:07.0 ISA bridge: Intel Corporation 82371AB PIIX4 ISA (rev 02)
00:07.1 IDE interface: Intel Corporation 82371AB PIIX4 IDE (rev 01)
00:07.2 USB Controller: Intel Corporation 82371AB PIIX4 USB (rev 01)
00:07.3 Bridge: Intel Corporation 82371AB PIIX4 ACPI (rev 02)
00:08.0 VGA compatible controller: S3 Inc. ViRGE/DX or /GX (rev 01)

$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 6
model name : Celeron (Mendocino)
stepping : 0
cpu MHz : 334.094
cache size : 128 KB
fdiv_bug : no
hlt_bug : no
sep_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr
bogomips : 666.82

Network card, hmm, some ne2k type ISA card. The phrase "8390" also springs
to mind.

$ less /var/log/dmesg
...
ne.c:v1.10 9/23/94 Donald Becker (becker@cesdis.gsfc.nasa.gov)
NE*000 ethercard probe at 0x300: 00 00 e8 2f b9 ca
eth0: NE2000 found at 0x300, using IRQ 5.
...

Stock kernel. No patches. Unfortunately I've lost .config

BTW ipv6 module is loaded, for extra coolness points. Not that I use it! :)

I can provide a dissassembly of tcp_recvmsg; please quote "c0162daf" - that
is where the inews's were all sleeping.

Hmm, curiouser and curiouser. I haven't booted the (this) machine since
77 days ago; and now dmesg shows another couple of messages:

recvmsg bug: copied 870A11AD seq 0
recvmsg bug: copied 870A11AD seq 0
tcp_close: socket already locked!

Same "copied" sequence number! Pity the kernel doesn't timestamp its
messages. Why doesn't syslog catch these messages into /var/log/messages?

I'll leave the machine running (unless it gets *very* weird) so we can peek
its memory. Is it too late to copy /proc/kcore now?

Hah! I bet this has *something* to do with the whole spiel:
$ netstat -nt |grep human-brain
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 6 0 127.0.0.1:3287 127.0.0.1:119 CLOSE

When I su to root and add netstat's -p option, this socket doesn't have an
owner process. And I use rtin, not some pthread-monster, so it's not that.

[I'd greatly appreciate Cc'ed replies]

-- 
berndfoobar@users.sourceforge.net is probably better to bookmark than any
employer-specific email address I may have appearing in the headers.
  Vanity page: http://www.tsct.co.za/~berndj/
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