1 // SPDX-License-Identifier: GPL-2.0
8 /* This must match the huge page & THP size */
9 #define SIZE (16 * 1024 * 1024)
11 static int test_body(void)
16 addr = (void *)0xa0000000;
18 p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
19 MAP_HUGETLB | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
20 if (p != MAP_FAILED) {
22 * Typically the mmap will fail because no huge pages are
23 * allocated on the system. But if there are huge pages
24 * allocated the mmap will succeed. That's fine too, we just
25 * munmap here before continuing. munmap() length of
26 * MAP_HUGETLB memory must be hugepage aligned.
28 if (munmap(addr, SIZE)) {
34 p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
35 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
36 if (p == MAP_FAILED) {
37 printf("Mapping failed @ %p\n", addr);
43 * Either a user or kernel access is sufficient to trigger the bug.
44 * A kernel access is easier to spot & debug, as it will trigger the
45 * softlockup or RCU stall detectors, and when the system is kicked
46 * into xmon we get a backtrace in the kernel.
51 * For the purposes of this testcase it's preferable to spin in
52 * userspace, so the harness can kill us if we get stuck. That way we
53 * see a test failure rather than a dead system.
62 static int test_main(void)
66 /* 10,000 because it's a "bunch", and completes reasonably quickly */
67 for (i = 0; i < 10000; i++)
76 return test_harness(test_main, "hugetlb_vs_thp");