74 lines · c
1// SPDX-License-Identifier: GPL-2.02#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 10014 15char *huge_ptr;16 17/* Touch the memory while it is being madvised() */18void *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 28void *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 38int 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 ~100044 * interactions45 */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