Date: Mon, 6 Mar 1995 20:31:32 -0500 From: starkhome!gene@sbstark.cs.sunysb.edu (Gene Stark) To: current@freebsd.org Subject: How to deadlock your -current system Message-ID: <199503070131.UAA00178@starkhome.cs.sunysb.edu>
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Here is a fairly reliable way to cause a deadlock on my 16MB system
running -current. I tried to make the size of the file comparable to
the size of my RAM. I don't know if other sizes cause the same problem.
- Gene
-------------
#include <stdio.h>
#include <unistd.h>
#include <sys/fcntl.h>
#include <sys/types.h>
#include <sys/mman.h>
#define PSIZE 4096
main()
{
char *name = "testfile";
off_t max = 4000*PSIZE;
char buf[PSIZE];
caddr_t addr;
int f;
if((f = open(name, O_CREAT | O_RDWR, 0644)) < 0) {
perror("Can't open test file");
exit(1);
}
if(lseek(f, max-PSIZE, SEEK_SET) < 0) {
perror("Seek failed");
exit(1);
}
if(write(f, buf, PSIZE) < 0) {
perror("Initial write failed");
exit(1);
}
if((addr = mmap(0, max, PROT_READ | PROT_WRITE, MAP_SHARED, f, 0))
== NULL) {
perror("mmap failed");
exit(1);
}
while(1) {
int r = random() % max - 1;
*(addr + r) = 0;
}
}
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