I found that running the following program as an unprivileged user on
Linux/IA-64 could hang the system.

#include <unistd.h>
#include <sys/mman.h>

int main(int argc, char **argv)
{
        munmap( (void *) 0x2000000000000000L, 0x2000000000000000L - 1); 
}

The attached patch fixes the problem. We recommend that distributions 
pick this up as soon as possible, because of the nature of the problem.

    -Arun