// SPDX-License-Identifier: GPL-2.0
|
#include <stdio.h>
|
#include <sys/mman.h>
|
#include <unistd.h>
|
|
#include "utils.h"
|
|
/* This must match the huge page & THP size */
|
#define SIZE (16 * 1024 * 1024)
|
|
static int test_body(void)
|
{
|
void *addr;
|
char *p;
|
|
addr = (void *)0xa0000000;
|
|
p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
|
MAP_HUGETLB | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
|
if (p != MAP_FAILED) {
|
/*
|
* Typically the mmap will fail because no huge pages are
|
* allocated on the system. But if there are huge pages
|
* allocated the mmap will succeed. That's fine too, we just
|
* munmap here before continuing. munmap() length of
|
* MAP_HUGETLB memory must be hugepage aligned.
|
*/
|
if (munmap(addr, SIZE)) {
|
perror("munmap");
|
return 1;
|
}
|
}
|
|
p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
|
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
|
if (p == MAP_FAILED) {
|
printf("Mapping failed @ %p\n", addr);
|
perror("mmap");
|
return 1;
|
}
|
|
/*
|
* Either a user or kernel access is sufficient to trigger the bug.
|
* A kernel access is easier to spot & debug, as it will trigger the
|
* softlockup or RCU stall detectors, and when the system is kicked
|
* into xmon we get a backtrace in the kernel.
|
*
|
* A good option is:
|
* getcwd(p, SIZE);
|
*
|
* For the purposes of this testcase it's preferable to spin in
|
* userspace, so the harness can kill us if we get stuck. That way we
|
* see a test failure rather than a dead system.
|
*/
|
*p = 0xf;
|
|
munmap(addr, SIZE);
|
|
return 0;
|
}
|
|
static int test_main(void)
|
{
|
int i;
|
|
/* 10,000 because it's a "bunch", and completes reasonably quickly */
|
for (i = 0; i < 10000; i++)
|
if (test_body())
|
return 1;
|
|
return 0;
|
}
|
|
int main(void)
|
{
|
return test_harness(test_main, "hugetlb_vs_thp");
|
}
|
