Re: [uml-devel] actually useful backtrace from a CPU-chewing hang

[Nix <nix@esperi.org.uk>]

On 25 Apr 2008, nix@esperi.org.uk told this:

> I suspect this can go wrong anywhere, but it happens to have been a
> CBQ-triggered gettimeofday() while sending an arp that did it. (My ADSL
> router pretty much bombs the poor damn machine with ARP packets all the
> time.)

Woo, it's happening a lot tonight.

The CBQ/ARP problem recurred, and also this:

(gdb) bt
#0  0xb7f87410 in __kernel_vsyscall ()
#1  0x45f27b36 in gettimeofday () from /lib/libc.so.6
#2  0x08065417 in os_nsecs () at arch/um/os-Linux/time.c:79
#3  0x080590fc in itimer_read () at arch/um/kernel/time.c:77
#4  0x08084a5f in update_wall_time () at include/linux/clocksource.h:167
#5  0x08077ba1 in do_timer (ticks=1) at kernel/timer.c:929
#6  0x08086350 in tick_periodic (cpu=0) at kernel/time/tick-common.c:66
#7  0x08086382 in tick_handle_periodic (dev=0x821d384) at kernel/time/tick-common.c:82
#8  0x080590ed in um_timer (irq=0, dev=0x0) at arch/um/kernel/time.c:70
#9  0x0808d42f in handle_IRQ_event (irq=0, action=0xdc49480) at kernel/irq/handle.c:140
#10 0x0808d4ad in __do_IRQ (irq=0) at kernel/irq/handle.c:236
#11 0x080576f8 in do_IRQ (irq=0, regs=0x8217ec4) at arch/um/kernel/irq.c:335
#12 0x080590a0 in timer_handler (sig=26, regs=0x8217ec4) at arch/um/kernel/time.c:28
#13 0x08064c84 in real_alarm_handler (sc=0x0) at arch/um/os-Linux/signal.c:93
#14 0x08064cac in alarm_handler (sig=26, sc=0x0) at arch/um/os-Linux/signal.c:108
#15 0x080654a0 in deliver_alarm () at arch/um/os-Linux/time.c:117
#16 0x08065640 in idle_sleep (nsecs=<value optimized out>) at arch/um/os-Linux/time.c:181
#17 0x080580d4 in default_idle () at arch/um/kernel/process.c:248
#18 0x080580fe in cpu_idle () at arch/um/kernel/process.c:256
#19 0x081afdee in rest_init () at init/main.c:453
#20 0x0804953b in start_kernel () at init/main.c:650
#21 0x0804a7e1 in start_kernel_proc (unused=0x0) at arch/um/kernel/skas/process.c:46
#22 0x08064261 in run_kernel_thread (fn=0x804a7b5 <start_kernel_proc>, arg=0x0, jmp_ptr=0x821d184) at arch/um/os-Linux/process.c:267
#23 0x08057ee0 in new_thread_handler () at arch/um/kernel/process.c:151
#24 0x00000000 in ?? ()

It looks to me like os_nsecs()/gettimeofday()/et al are the only really
important parts of this backtrace.

-- 
`If you are having a "ua luea luea le ua le" kind of day, I can only
 assume that you are doing no work due [to] incapacitating nausea caused 
 by numerous lazy demons.' --- Frossie

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