Re: The Deadly `ping -f'

Taneli Vahakangas (taneli@firmament.fi)
Sun, 18 Apr 1999 12:23:37 +0300 (EEST)


Hello Greg, all,

On Sat, 17 Apr 1999, Greg Zornetzer wrote:

> On Sun, 18 Apr 1999, Taneli Vahakangas wrote:
> > The machine fell into the ever-interesting land of __delay, __udelay and
> > __global_cli (as witnessed with SysRq-P), and was not able to respond
> > outside pings. Unfortunately, SysRq-U (or -S) didn't work.
> I tried to reproduce this quickly on my machine: Uniprocessor with 3c509
> compiled into the kernel. I ran a flood ping (using Alexy Kuznetsov's
> fixed ping program) from my machine to 2 other machines on a personal lan,
> as well as a flood ping to the machine's own ethernet address, and a flood
> ping on loopback. The machine was totally stable (if a bit slow) - it's a
> P66.
>
> Anyway, maybe the problem is some SMP locking issue not present on UP.
> Could you try recompiling the kernel uniprocessor and run the exact same
> test (just be careful you remake all of the modules uniprocessor).

Yes, it is SMP indeed. A UP kernel+modules works allright, using either
3c509 or eexpress. A SMP kernel fails with both. The eexpress driver is
more interesting, though, it spits out these:

eth0: tx interrupt but no status

while doing "The Double Flood Ping" and afterwards all networking is
wedged, it only says:

eth0: i82586 reset timed out, kicking (5 times in a row)
eth0: i82586 not responding, giving up.

Then I said
# ifconfig down
# ifconfig up
and the machine locked up again. But as I said, UP kernel works pretty
well -- although it says "tx interrupt but no status" during ping -f, it
doesn't crash the machine.

Taneli <taneli@firmament.fi>

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