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 18 int 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 if (alloc == MAP_FAILED) { 30 if ((errno == EOPNOTSUPP) || (errno == EINVAL)) { 31 ksft_test_result_skip("MAP_DROPPABLE not supported\n"); 32 exit(KSFT_SKIP); 33 } 34 ksft_test_result_fail("mmap error: %s\n", strerror(errno)); 35 exit(KSFT_FAIL); 36 } 37 memset(alloc, 'A', alloc_size); 38 for (size_t i = 0; i < alloc_size; i += page_size) 39 assert(*(uint8_t *)(alloc + i)); 40 41 child = fork(); 42 assert(child >= 0); 43 if (!child) { 44 for (;;) 45 *(char *)malloc(page_size) = 'B'; 46 } 47 48 for (bool done = false; !done;) { 49 for (size_t i = 0; i < alloc_size; i += page_size) { 50 if (!*(uint8_t *)(alloc + i)) { 51 done = true; 52 break; 53 } 54 } 55 } 56 kill(child, SIGTERM); 57 58 ksft_test_result_pass("MAP_DROPPABLE: PASS\n"); 59 exit(KSFT_PASS); 60 } 61