[CFT] SIFTR - Statistical Information For TCP Research: Uncle Lawrence needs YOU!

Fabian Keil freebsd-listen at fabiankeil.de
Sat Jun 19 17:58:12 UTC 2010

Lawrence Stewart <lstewart at freebsd.org> wrote:

> On 06/13/10 18:12, Lawrence Stewart wrote:

> > The time has come to solicit some external testing for my SIFTR tool.
> > I'm hoping to commit it within a week or so unless problems are discovered.

> > I'm interested in all feedback and reports of success/failure, along
> > with details of the architecture tested and number of CPUs if you would
> > be so kind.

I got the following hand-transcribed panic maybe a second after
sysctl net.inet.siftr.enabled=1

Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
current process = 12 (swi4: clock)
[ thread pid 12 tid 100006 ]
Stopped at	siftr_chkpkt+0xd0:	addq	$0x1,0x8(%r14)
db> where
Tracing pid 12 tid 100006 td 0xffffff00034037e0
siftr_chkpt() at siftr_chkpkt+0xd0
pfil_run_hooks() at pfil_run_hooks+0xb4
ip_output() at ip_output+0x382
tcp_output() tcp_output+0xa41
tcp_timer_rexmt() at tcp_timer_rexmt+0x251
softclock() at softclock+0x291
intr_event_execute_handlers() at intr_event_execute_handlers+0x66
ithread_loop at ithread_loop+0x8e
fork_exit() at fork_exit+0x112
fork_trampoline() at fork_trampoline+0xe
--- trap 0, rip = 0, rsp = 0xffffff800003ad30, rbp = 0 ---

This is from the third attempt, the second time I got a different
backtrace that also contained some *_iwn_* functions, the first
time I had X running, so I didn't get anything. Unfortunately
at that point the system seems to be too busted to dump core.

I'm using:
FreeBSD 9.0-CURRENT #99 r+b768fe1: Sat Jun 19 15:01:37 CEST 2010
    fk at r500.local:/usr/obj/usr/src/sys/ZOEY amd64
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Core(TM)2 Duo CPU     T5870  @ 2.00GHz (1995.01-MHz K8-class CPU)
  Origin = "GenuineIntel"  Id = 0x6fd  Family = 6  Model = f  Stepping = 13
  AMD Features=0x20100800<SYSCALL,NX,LM>
  AMD Features2=0x1<LAHF>
  TSC: P-state invariant
real memory  = 2147483648 (2048 MB)
avail memory = 1976610816 (1885 MB)
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
FreeBSD/SMP: 1 package(s) x 2 core(s)
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP): APIC ID:  1
ioapic0: Changing APIC ID to 1
ioapic0 <Version 2.0> irqs 0-23 on motherboard

I'm not using vanilla sources, but none of the modifications
should matter here.

I have powerd running and did not yet try without it.

The system has bge0 and iwn0, but bge0 is mainly down.

pf is compiled into the kernel, siftr is loaded as a module.

The panic seems to occur without logging a single packet first:
fk at r500 ~ $cat /var/log/siftr.log 
enable_time_secs=1276966161     enable_time_usecs=945080        siftrver=1.2.3  hz=100  tcp_rtt_scale=32        sysname=FreeBSD sysver=900014   ipmode=4
enable_time_secs=1276966586     enable_time_usecs=314023        siftrver=1.2.3  hz=100  tcp_rtt_scale=32        sysname=FreeBSD sysver=900014   ipmode=4

I get the impression that this is reproducible, but only tried
three times (the last time with everything mounted read-only).

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