From owner-freebsd-hackers  Wed Aug 11  9:49: 2 1999
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Date: Wed, 11 Aug 1999 20:48:08 +0400 (MSD)
From: Oleg Derevenetz <oleg@oleg.sani-c.vrn.ru>
Message-Id: <199908111648.UAA01527@oleg.sani-c.vrn.ru>
To: freebsd-hackers@freebsd.org
Subject: mmap bug
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG


This small program, running as 'mmap', not 'mmap -u', can hang my machine. 
Is this a known bug in FreeBSD's kernel, or it is my fantasy ? 
Thank you for answer.

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
  
main(int argc, char *argv[])
{
     int fd;
     int i;
     int len=1024*1024*10;  /*ie 10Mbytes*/
     caddr_t addr;
     char ttt[80];
     int bunlink = 0;
 
     if ( argc > 1 && strcmp(argv[1], "-u") == 0 ) {
       bunlink = 1;
     }
     printf("unlink files? %s\n", bunlink ? "YES" : "NO");
   
     for (i=0;;i++)
     {
     sprintf (ttt,"%d",i);
     printf("mmaping %ld byte region on file %s\n", len, ttt);
     fd=open(ttt,O_CREAT|O_RDWR,0666);
     if (fd<0)
     {
        printf("mmap error %ld",errno);
        exit(1);
     }
     memset(addr,'x',len);
     if ( munmap(addr, len) != 0 ) {
       fprintf(stderr, "munmap failed\n");
       exit(EXIT_FAILURE);
     }
     close(fd);
     if ( bunlink ) unlink(ttt);
     }
}


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