mmaptest.log

% uname -ap
NetBSD subq 9.99.69 NetBSD 9.99.69 (GENERIC.SUBQ) #37: Sun Jul  5 02:54:58 JST 2020  ryo@subq:/usr/src/sys/arch/amd64/compile/GENERIC.SUBQ amd64 x86_64

% cat mmaptest.c 
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>

char path_procmap[128];

static void
procmap(void)
{
	int fd;
	ssize_t r;
	char buf[1024 * 8];
	if (path_procmap[0] == '\0') {
		snprintf(path_procmap, sizeof(path_procmap), "/proc/%d/map", getpid());
	}
	fd = open(path_procmap, O_RDONLY);
	if (fd < 0)
		errx(1, "open: %s", path_procmap);
	printf("[%s]\n", path_procmap);
	do {
		r = read(fd, buf, sizeof(buf));
		if (r > 0)
			fwrite(buf, r, 1, stdout);
	} while (r == sizeof(buf));
	printf("\n");
	close(fd);
}

int
main()
{
	void *p, *result;
	int i;

	p = (void *)0x400000LL;

	for (;;) {
		procmap();

		printf("do mmap(%p,,,,,)\n", p);
		result = mmap(p, getpagesize(), PROT_NONE, MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS, 0xffffffff, 0);
		if (result == MAP_FAILED)
			err(1, "mmap");

		printf("mmap(%p,,,,,) -> %p\n\n", p, result);
	}

	return 0;
}

% cc mmaptest.c 

% ./a.out 
[/proc/3041/map]
0x400000 0x402000 r-x r-x COW NC 1 0 0
0x601000 0x602000 rw- rw- COW NNC 1 0 0
0x7f7ff6e00000 0x7f7ff6e10000 rw- rw- COW NNC 1 0 0
0x7f7ff6e10000 0x7f7ff6fb0000 rw- rw- COW NC 1 0 0
0x7f7ff6fb0000 0x7f7ff6fc0000 rw- rw- COW NNC 1 0 0
0x7f7ff6fc0000 0x7f7ff7200000 rw- rw- COW NC 1 0 0
0x7f7ff7200000 0x7f7ff7210000 rw- rw- COW NNC 1 0 0
0x7f7ff7210000 0x7f7ff7400000 rw- rw- COW NC 1 0 0
0x7f7ff7400000 0x7f7ff75d5000 r-x r-x COW NC 1 0 0
0x7f7ff75d5000 0x7f7ff77d4000 --- r-x COW NC 1 0 0
0x7f7ff77d4000 0x7f7ff77e0000 r-- rw- COW NNC 1 0 0
0x7f7ff77e0000 0x7f7ff77e6000 rw- rw- COW NNC 1 0 0
0x7f7ff77e6000 0x7f7ff7800000 rw- rw- COW NNC 1 0 0
0x7f7ff7800000 0x7f7ff78f0000 rw- rw- COW NC 1 0 0
0x7f7ff78f0000 0x7f7ff7900000 rw- rw- COW NNC 1 0 0
0x7f7ff7900000 0x7f7ff79f0000 rw- rw- COW NC 1 0 0
0x7f7ff79f0000 0x7f7ff7a08000 rw- rw- COW NNC 1 0 0
0x7f7ff7c00000 0x7f7ff7c0f000 r-x r-x COW NC 1 0 0
0x7f7ff7c0f000 0x7f7ff7e0f000 --- --- COW NC 1 0 0
0x7f7ff7e0f000 0x7f7ff7e10000 rw- rw- COW NNC 1 0 0
0x7f7ff7e10000 0x7f7ff7e11000 rw- rw- COW NNC 1 0 0
0x7f7ff7ee3000 0x7f7ff7eff000 rw- rw- COW NNC 1 0 0
0x7f7ff7eff000 0x7f7ff8fff000 --- --- COW NC 1 0 0
0x7f7ff8fff000 0x7f7fffff0000 rw- rw- COW NC 1 0 0
0x7f7fffff0000 0x7f7ffffff000 rw- rw- COW NNC 1 0 0

do mmap(0x400000,,,,,)
mmap(0x400000,,,,,) -> 0x3ff000

[/proc/3041/map]
0x3ff000 0x400000 --- --- COW NC 1 0 0
0x400000 0x402000 r-x r-x COW NC 1 0 0
0x601000 0x602000 rw- rw- COW NNC 1 0 0
0x7f7ff6e00000 0x7f7ff6e10000 rw- rw- COW NNC 1 0 0
0x7f7ff6e10000 0x7f7ff6fb0000 rw- rw- COW NC 1 0 0
0x7f7ff6fb0000 0x7f7ff6fc0000 rw- rw- COW NNC 1 0 0
0x7f7ff6fc0000 0x7f7ff7200000 rw- rw- COW NC 1 0 0
0x7f7ff7200000 0x7f7ff7210000 rw- rw- COW NNC 1 0 0
0x7f7ff7210000 0x7f7ff7400000 rw- rw- COW NC 1 0 0
0x7f7ff7400000 0x7f7ff75d5000 r-x r-x COW NC 1 0 0
0x7f7ff75d5000 0x7f7ff77d4000 --- r-x COW NC 1 0 0
0x7f7ff77d4000 0x7f7ff77e0000 r-- rw- COW NNC 1 0 0
0x7f7ff77e0000 0x7f7ff77e6000 rw- rw- COW NNC 1 0 0
0x7f7ff77e6000 0x7f7ff7800000 rw- rw- COW NNC 1 0 0
0x7f7ff7800000 0x7f7ff78f0000 rw- rw- COW NC 1 0 0
0x7f7ff78f0000 0x7f7ff7900000 rw- rw- COW NNC 1 0 0
0x7f7ff7900000 0x7f7ff79f0000 rw- rw- COW NC 1 0 0
0x7f7ff79f0000 0x7f7ff7a08000 rw- rw- COW NNC 1 0 0
0x7f7ff7c00000 0x7f7ff7c0f000 r-x r-x COW NC 1 0 0
0x7f7ff7c0f000 0x7f7ff7e0f000 --- --- COW NC 1 0 0
0x7f7ff7e0f000 0x7f7ff7e10000 rw- rw- COW NNC 1 0 0
0x7f7ff7e10000 0x7f7ff7e11000 rw- rw- COW NNC 1 0 0
0x7f7ff7ee3000 0x7f7ff7eff000 rw- rw- COW NNC 1 0 0
0x7f7ff7eff000 0x7f7ff8fff000 --- --- COW NC 1 0 0
0x7f7ff8fff000 0x7f7fffff0000 rw- rw- COW NC 1 0 0
0x7f7fffff0000 0x7f7ffffff000 rw- rw- COW NNC 1 0 0

do mmap(0x400000,,,,,)
a.out: mmap: Cannot allocate memory