Add selftest specific to madvise collapse context that tests
MADV_COLLAPSE is "successful" if a hugepage-aligned/sized region is
already pmd-mapped.
This test also verifies that MADV_COLLAPSE can collapse memory into THPs
even in "madvise" THP mode and the memory isn't marked VM_HUGEPAGE.
Signed-off-by: Zach O'Keefe <zokeefe@xxxxxxxxxx>
---
tools/testing/selftests/vm/khugepaged.c | 31 +++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/tools/testing/selftests/vm/khugepaged.c b/tools/testing/selftests/vm/khugepaged.c
index 5207930b34a4..eeea84b0cd35 100644
--- a/tools/testing/selftests/vm/khugepaged.c
+++ b/tools/testing/selftests/vm/khugepaged.c
@@ -918,6 +918,36 @@ static void collapse_max_ptes_shared(struct collapse_context *c)
munmap(p, hpage_pmd_size);
}
+static void madvise_collapse_existing_thps(void)
+{
+ void *p;
+ int err;
+
+ p = alloc_mapping();
+ fill_memory(p, 0, hpage_pmd_size);
+
+ printf("Collapse fully populated PTE table...");
+ /*
+ * Note that we don't set MADV_HUGEPAGE here, which
+ * also tests that VM_HUGEPAGE isn't required for
+ * MADV_COLLAPSE in "madvise" mode.
+ */
+ err = madvise(p, hpage_pmd_size, MADV_COLLAPSE);
+ if (err == 0 && check_huge(p)) {
+ success("OK");
+ printf("Re-collapse PMD-mapped hugepage");
+ err = madvise(p, hpage_pmd_size, MADV_COLLAPSE);
+ if (err == 0 && check_huge(p))
+ success("OK");
+ else
+ fail("Fail");
+ } else {
+ fail("Fail");
+ }
+ validate_memory(p, 0, hpage_pmd_size);
+ munmap(p, hpage_pmd_size);
+}
+
static void madvise_collapse(const char *msg, char *p, bool expect)
{
int ret;
@@ -1050,6 +1080,7 @@ int main(void)
collapse_fork(&c);
collapse_fork_compound(&c);
collapse_max_ptes_shared(&c);
+ madvise_collapse_existing_thps();
restore_settings(0);
}
--
2.36.1.255.ge46751e96f-goog
