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// SPDX-License-Identifier: GPL-2.0
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#include "vm_util.h"
#include "../kselftest.h"
#define MMAP_SIZE (1 << 21)
#define INLOOP_ITER 100
char *huge_ptr;
/* Touch the memory while it is being madvised() */
void *touch(void *unused)
{
char *ptr = (char *)huge_ptr;
for (int i = 0; i < INLOOP_ITER; i++)
ptr[0] = '.';
return NULL;
}
void *madv(void *unused)
{
usleep(rand() % 10);
for (int i = 0; i < INLOOP_ITER; i++)
madvise(huge_ptr, MMAP_SIZE, MADV_DONTNEED);
return NULL;
}
int main(void)
{
unsigned long free_hugepages;
pthread_t thread1, thread2;
/*
* On kernel 6.4, we are able to reproduce the problem with ~1000
* interactions
*/
int max = 10000;
srand(getpid());
free_hugepages = get_free_hugepages();
if (free_hugepages != 1) {
ksft_exit_skip("This test needs one and only one page to execute. Got %lu\n",
free_hugepages);
}
while (max--) {
huge_ptr = mmap(NULL, MMAP_SIZE, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
-1, 0);
if ((unsigned long)huge_ptr == -1)
ksft_exit_skip("Failed to allocated huge page\n");
pthread_create(&thread1, NULL, madv, NULL);
pthread_create(&thread2, NULL, touch, NULL);
pthread_join(thread1, NULL);
pthread_join(thread2, NULL);
munmap(huge_ptr, MMAP_SIZE);
}
return KSFT_PASS;
}
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