Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4 */
5
6#include <assert.h>
7#include <stdbool.h>
8#include <stdint.h>
9#include <stdio.h>
10#include <stdlib.h>
11#include <unistd.h>
12#include <signal.h>
13#include <sys/mman.h>
14#include <linux/mman.h>
15
16#include "../kselftest.h"
17
18int main(int argc, char *argv[])
19{
20 size_t alloc_size = 134217728;
21 size_t page_size = getpagesize();
22 void *alloc;
23 pid_t child;
24
25 ksft_print_header();
26 ksft_set_plan(1);
27
28 alloc = mmap(0, alloc_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
29 assert(alloc != MAP_FAILED);
30 memset(alloc, 'A', alloc_size);
31 for (size_t i = 0; i < alloc_size; i += page_size)
32 assert(*(uint8_t *)(alloc + i));
33
34 child = fork();
35 assert(child >= 0);
36 if (!child) {
37 for (;;)
38 *(char *)malloc(page_size) = 'B';
39 }
40
41 for (bool done = false; !done;) {
42 for (size_t i = 0; i < alloc_size; i += page_size) {
43 if (!*(uint8_t *)(alloc + i)) {
44 done = true;
45 break;
46 }
47 }
48 }
49 kill(child, SIGTERM);
50
51 ksft_test_result_pass("MAP_DROPPABLE: PASS\n");
52 exit(KSFT_PASS);
53}