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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 <setjmp.h>
#include <signal.h>
#include "vm_util.h"
#include "../kselftest.h"
#define INLOOP_ITER 100
static char *huge_ptr;
static size_t huge_page_size;
static sigjmp_buf sigbuf;
static bool sigbus_triggered;
static void signal_handler(int signal)
{
if (signal == SIGBUS) {
sigbus_triggered = true;
siglongjmp(sigbuf, 1);
}
}
/* Touch the memory while it is being madvised() */
void *touch(void *unused)
{
char *ptr = (char *)huge_ptr;
if (sigsetjmp(sigbuf, 1))
return NULL;
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, huge_page_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;
int err;
ksft_print_header();
ksft_set_plan(1);
srand(getpid());
if (signal(SIGBUS, signal_handler) == SIG_ERR)
ksft_exit_skip("Could not register signal handler.");
huge_page_size = default_huge_page_size();
if (!huge_page_size)
ksft_exit_skip("Could not detect default hugetlb page size.");
ksft_print_msg("[INFO] detected default hugetlb page size: %zu KiB\n",
huge_page_size / 1024);
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, huge_page_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, huge_page_size);
}
ksft_test_result(!sigbus_triggered, "SIGBUS behavior\n");
err = ksft_get_fail_cnt();
if (err)
ksft_exit_fail_msg("%d out of %d tests failed\n",
err, ksft_test_num());
ksft_exit_pass();
}
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