kern/84952: "panic: sbappendstream 1" while using net/mpd

[Jimmy Olgeni]

>Number:         84952
>Category:       kern
>Synopsis:       "panic: sbappendstream 1" while using net/mpd
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Aug 15 14:20:08 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Jimmy Olgeni
>Release:        FreeBSD 6.0-BETA2 i386
>Organization:
>Environment:
System: FreeBSD olgeni.olgeni 6.0-BETA2 FreeBSD 6.0-BETA2 #2: Sat Aug 13 22:03:12 CEST 2005 olgeni at olgeni.olgeni:/usr/obj/usr/src/sys/GENERIC i386
>Description:

While downloading data on a net/mpd GRE link, the following panic will occur:

#0  doadump () at pcpu.h:165
165	pcpu.h: No such file or directory.
	in pcpu.h
(kgdb) bt
#0  doadump () at pcpu.h:165
#1  0xc0631ea8 in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:397
#2  0xc06321bd in panic (fmt=0xc085d9c7 "sbappendstream 1")
    at /usr/src/sys/kern/kern_shutdown.c:553
#3  0xc066e296 in sbappendstream_locked (sb=0xc27f2050, m=0xc222b600)
    at /usr/src/sys/kern/uipc_socket2.c:741
#4  0xc06c8880 in tcp_input (m=0xc222b600, off0=20)
    at /usr/src/sys/netinet/tcp_input.c:1280
#5  0xc06c1c91 in ip_input (m=0xc222b600)
    at /usr/src/sys/netinet/ip_input.c:776
#6  0xc06a0cd6 in netisr_processqueue (ni=0xc096f7b8)
    at /usr/src/sys/net/netisr.c:235
#7  0xc06a0eba in swi_net (dummy=0x0) at /usr/src/sys/net/netisr.c:348
#8  0xc061f9b8 in ithread_loop (arg=0xc1e33480)
    at /usr/src/sys/kern/kern_intr.c:545
#9  0xc061edec in fork_exit (callout=0xc061f89c <ithread_loop>, 
    arg=0xc1e33480, frame=0xd58d3d38) at /usr/src/sys/kern/kern_fork.c:789
#10 0xc07dc2dc in fork_trampoline () at /usr/src/sys/i386/i386/exception.s:208

A similar panic ("sbdrop") occurs on recent RELENG_5.

>How-To-Repeat:

Running any verbose command over a ssh link ("find /") will panic the client side.

>Fix:

Using ppp over tcp between the same hosts does not trigger the panic.
>Release-Note:
>Audit-Trail:
>Unformatted: