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
9 #include "vm_util.h"
10 #include "../kselftest.h"
11
12 #define MMAP_SIZE (1 << 21)
13 #define INLOOP_ITER 100
14
15 char *huge_ptr;
16
17 /* Touch the memory while it is being madvised() */
18 void *touch(void *unused)
19 {
20 char *ptr = (char *)huge_ptr;
21
22 for (int i = 0; i < INLOOP_ITER; i++)
23 ptr[0] = '.';
24
25 return NULL;
26 }
27
28 void *madv(void *unused)
29 {
30 usleep(rand() % 10);
31
32 for (int i = 0; i < INLOOP_ITER; i++)
33 madvise(huge_ptr, MMAP_SIZE, MADV_DONTNEED);
34
35 return NULL;
36 }
37
38 int main(void)
39 {
40 unsigned long free_hugepages;
41 pthread_t thread1, thread2;
42 /*
43 * On kernel 6.4, we are able to reproduce the problem with ~1000
44 * interactions
45 */
46 int max = 10000;
47
48 srand(getpid());
49
50 free_hugepages = get_free_hugepages();
51 if (free_hugepages != 1) {
52 ksft_exit_skip("This test needs one and only one page to execute. Got %lu\n",
53 free_hugepages);
54 }
55
56 while (max--) {
57 huge_ptr = mmap(NULL, MMAP_SIZE, PROT_READ | PROT_WRITE,
58 MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
59 -1, 0);
60
61 if ((unsigned long)huge_ptr == -1)
62 ksft_exit_skip("Failed to allocated huge page\n");
63
64 pthread_create(&thread1, NULL, madv, NULL);
65 pthread_create(&thread2, NULL, touch, NULL);
66
67 pthread_join(thread1, NULL);
68 pthread_join(thread2, NULL);
69 munmap(huge_ptr, MMAP_SIZE);
70 }
71
72 return KSFT_PASS;
73 }
74
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