Date: 08 May 2001 23:18:23 +0200 From: Dag-Erling Smorgrav <des@ofug.org> To: tlambert2@mindspring.com Cc: Dennis Glatting <dennis.glatting@software-munitions.com>, Kris Kennaway <kris@obsecurity.org>, freebsd-stable@frebsd.org, freebsd-current@FreeBSD.ORG Subject: Re: pgm to kill 4.3 via vm Message-ID: <xzp8zk7k09s.fsf@flood.ping.uio.no> In-Reply-To: <3AF81B16.7EC1F3DE@mindspring.com> References: <20010507074503.Y24943-100000@btw.plaintalk.bellevue.wa.us> <xzpy9s9mbyl.fsf@flood.ping.uio.no> <3AF81B16.7EC1F3DE@mindspring.com>
next in thread | previous in thread | raw e-mail | index | archive | help
[-- Attachment #1 --]
Good question. It does some non-trivial stuff besides allocating:
buffered I/O and fork()/exec()'ing sync(1).
> Your suggested replacement test might be fun to run, but I
> think it wouldn't lock up 4.3...
Nope. But the attached - much nastier - program did trash my -CURRENT
box when run as root in an xterm. What happened was that the X server
faulted and died, rendering the console unusable; the serial console
filled up with getswapspace() errors, so the only recourse was a break
to DDB followed by 'call boot', which managed to sync all filesystems
except the root, but failed to actually reboot the machine.
I would *love* to have a DDB equivalent to 'kill -9', so I could drop
to the DDB prompt, check ps, kill a process or two, and drop back out
of DDB. It would have saved me a reboot and a longish fsck in this
case.
A second try, on the text console and as a regular user, got to 643 MB
before it, top(1) and an xterm were killed. This is a 5.0-CURRENT
system with 192 MB RAM and 512 MB swap, so 643 MB is pretty close to
max capacity.
DES
--
Dag-Erling Smorgrav - des@ofug.org
[-- Attachment #2 --]
#include <sys/types.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <unistd.h>
#define CHUNKSIZE 1048576
#define CHUNKS 4096
int
main(int argc, char *argv[])
{
int i, j, n, ps;
char *p;
n = (argc > 1) ? atoi(argv[1]) : CHUNKS;
ps = getpagesize();
for (i = 0; i < n; ++i) {
if ((p = mmap(NULL, CHUNKSIZE, PROT_WRITE, MAP_ANON, -1, 0)) == NULL) {
write(1, "\n:(\n", 4);
exit(1);
}
write(1, ".", 1);
for (j = 0; j < CHUNKSIZE; j += ps)
p[j] = 1;
}
write(1, "\n:)\n", 4);
read(0, p, 1);
exit(0);
}
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?xzp8zk7k09s.fsf>