1 // SPDX-License-Identifier: GPL-2.0
2 #include <pthread.h>
3 #include <stdio.h>
4 #include <stdlib.h>
5 #include <sys/mman.h>
6 #include <sys/types.h>
7 #include <unistd.h>
8 #include <setjmp.h>
9 #include <signal.h>
10
11 #include "vm_util.h"
12 #include "../kselftest.h"
13
14 #define INLOOP_ITER 100
15
16 static char *huge_ptr;
17 static size_t huge_page_size;
18
19 static sigjmp_buf sigbuf;
20 static bool sigbus_triggered;
21
signal_handler(int signal)22 static void signal_handler(int signal)
23 {
24 if (signal == SIGBUS) {
25 sigbus_triggered = true;
26 siglongjmp(sigbuf, 1);
27 }
28 }
29
30 /* Touch the memory while it is being madvised() */
touch(void * unused)31 void *touch(void *unused)
32 {
33 char *ptr = (char *)huge_ptr;
34
35 if (sigsetjmp(sigbuf, 1))
36 return NULL;
37
38 for (int i = 0; i < INLOOP_ITER; i++)
39 ptr[0] = '.';
40
41 return NULL;
42 }
43
madv(void * unused)44 void *madv(void *unused)
45 {
46 usleep(rand() % 10);
47
48 for (int i = 0; i < INLOOP_ITER; i++)
49 madvise(huge_ptr, huge_page_size, MADV_DONTNEED);
50
51 return NULL;
52 }
53
main(void)54 int main(void)
55 {
56 unsigned long free_hugepages;
57 pthread_t thread1, thread2;
58 /*
59 * On kernel 6.4, we are able to reproduce the problem with ~1000
60 * interactions
61 */
62 int max = 10000;
63 int err;
64
65 ksft_print_header();
66 ksft_set_plan(1);
67
68 srand(getpid());
69
70 if (signal(SIGBUS, signal_handler) == SIG_ERR)
71 ksft_exit_skip("Could not register signal handler.");
72
73 huge_page_size = default_huge_page_size();
74 if (!huge_page_size)
75 ksft_exit_skip("Could not detect default hugetlb page size.");
76
77 ksft_print_msg("[INFO] detected default hugetlb page size: %zu KiB\n",
78 huge_page_size / 1024);
79
80 free_hugepages = get_free_hugepages();
81 if (free_hugepages != 1) {
82 ksft_exit_skip("This test needs one and only one page to execute. Got %lu\n",
83 free_hugepages);
84 }
85
86 while (max--) {
87 huge_ptr = mmap(NULL, huge_page_size, PROT_READ | PROT_WRITE,
88 MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
89 -1, 0);
90
91 if ((unsigned long)huge_ptr == -1)
92 ksft_exit_skip("Failed to allocated huge page\n");
93
94 pthread_create(&thread1, NULL, madv, NULL);
95 pthread_create(&thread2, NULL, touch, NULL);
96
97 pthread_join(thread1, NULL);
98 pthread_join(thread2, NULL);
99 munmap(huge_ptr, huge_page_size);
100 }
101
102 ksft_test_result(!sigbus_triggered, "SIGBUS behavior\n");
103
104 err = ksft_get_fail_cnt();
105 if (err)
106 ksft_exit_fail_msg("%d out of %d tests failed\n",
107 err, ksft_test_num());
108 ksft_exit_pass();
109 }
110