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kern/49017: vfork does not suspend all threads

>Number:         49017
>Category:       kern
>Synopsis:       vfork does not suspend all threads
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jul 18 17:10:00 +0000 2014
>Originator:     Christos Zoulas
>Release:        NetBSD 6.99.47
        You've been vforked!
System: NetBSD 6.99.47 NetBSD 6.99.47 (QUASAR) #2: Fri Jul 18 
08:23:06 EDT 2014 
Architecture: x86_64
Machine: amd64
vfork is supposed to suspend the parent while the child is preparing for
exec. The parent is resumed after the child exec's or exits. This is done
so that the memory image shared between the parent and the child is not
changed by the parent while it is preparing to exec.
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>

#define NTHREAD 2

void *
worker(void *arg) {
        size_t *i = arg;
        for (size_t j = 0;; j++) {
                printf("[%d] %zu %zu\n", getpid(), *i, j);

main(int argc, char *argv[])
        pthread_t t[NTHREAD];

        for (size_t i = 0; i < NTHREAD; i++)
                pthread_create(&t[i], NULL, worker, &i);

        switch (vfork()) {
        case -1:
                err(1, "vfork");
        case 0:
        return 0;


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