From: "Kiryl Shutsemau (Meta)" <[email protected]> collapse_order_mixed_sources faults its region as order-2 folios and collapses them to the -o target, covering collapse of sources that are already large folios of an order below the target. But it only ever tests one source order, and order 2 sits below the contpte threshold on both arm64 page-size configs -- so a source-side contpte unfold is never exercised deterministically by this suite.
Let -s name the source order when combined with -o (it was rejected before): the mixed-source case then faults at order @anon_order instead of the fixed order 2, keeping order 2 as the default when -s is absent. -s stays constrained to a supported mTHP order strictly below the target; the other order-parameterized cases keep their order-0 sources (the source order is enabled locally, not globally), so -s under -o is a knob on the mixed-source case alone. This makes e.g. -s 5 -o 7 on arm64/64K collapse contpte-mapped sources into a larger mTHP, covering the source-unfold path directly. Assisted-by: Claude-Code:claude-opus-5 Signed-off-by: Kiryl Shutsemau (Meta) <[email protected]> --- tools/testing/selftests/mm/khugepaged.c | 42 +++++++++++++++++++------ 1 file changed, 32 insertions(+), 10 deletions(-) diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c index b074b005b62f..21a8fb24dc43 100644 --- a/tools/testing/selftests/mm/khugepaged.c +++ b/tools/testing/selftests/mm/khugepaged.c @@ -1363,28 +1363,32 @@ static void collapse_order_mixed_sources(struct collapse_context *c, struct mem_ops *ops) { struct thp_settings settings = *thp_current_settings(); + int source_order = anon_order ? anon_order : MIN_MTHP_ORDER; void *p; - if (anon_target_order <= MIN_MTHP_ORDER) { + /* Sources must be a supported mTHP order strictly below the target. */ + if (source_order >= anon_target_order || + !(thp_supported_orders() & (1UL << source_order))) { ksft_test_result_skip("%s: no source order below target\n", __func__); return; } - /* Fault the whole region as order-MIN_MTHP_ORDER folios. */ - settings.hugepages[MIN_MTHP_ORDER].enabled = THP_ALWAYS; + /* Fault the whole region as order-@source_order folios. */ + settings.hugepages[source_order].enabled = THP_ALWAYS; thp_push_settings(&settings); p = ops->setup_area(1); ops->fault(p, 0, hpage_pmd_size); thp_pop_settings(); - if (!is_range_backed_by_folio_orders(p, hpage_pmd_size, MIN_MTHP_ORDER, + if (!is_range_backed_by_folio_orders(p, hpage_pmd_size, source_order, pagemap_fd, kpageflags_fd)) ksft_exit_fail_msg("Region not backed by order-%d folios after fault\n", - MIN_MTHP_ORDER); + source_order); madvise(p, hpage_pmd_size, MADV_HUGEPAGE); - ksft_print_msg("Collapse region backed by smaller large folios..."); + ksft_print_msg("Collapse region backed by order-%d sources...", + source_order); if (!khugepaged_wait_full_pass()) fail("Timeout"); else if (range_collapsed(p, hpage_pmd_size)) @@ -1414,7 +1418,9 @@ static void usage(void) fprintf(stderr, "\t\t Defaults to 0. Use this size for anon or shmem allocations.\n"); fprintf(stderr, "\t\t-o: collapse target order for khugepaged:anon.\n"); fprintf(stderr, "\t\t Runs the order-parameterized collapse cases instead\n"); - fprintf(stderr, "\t\t of the PMD cases. Cannot be combined with -s.\n"); + fprintf(stderr, "\t\t of the PMD cases.\n"); + fprintf(stderr, "\t\t With -s, -s names the mTHP source order for the\n"); + fprintf(stderr, "\t\t mixed-source case (source order below the target).\n"); exit(1); } @@ -1438,7 +1444,15 @@ static void parse_test_type(int argc, char **argv) } } - if (anon_target_order && anon_order) + /* + * -s and -o compose: -s then names the mTHP source order for the + * mixed-source case, which needs a source strictly below the + * target (and at or above the smallest mTHP order). Alone, -s is + * the source order for the default PMD suite; alone, -o is the + * collapse target for the order-parameterized suite. + */ + if (anon_target_order && anon_order && + (anon_order < MIN_MTHP_ORDER || anon_order >= anon_target_order)) usage(); argv += optind; @@ -1573,9 +1587,17 @@ int main(int argc, char **argv) default_settings.khugepaged.max_ptes_shared = hpage_pmd_nr / 2; default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8; default_settings.hugepages[hpage_pmd_order].enabled = THP_INHERIT; - default_settings.hugepages[anon_order].enabled = THP_ALWAYS; default_settings.shmem_hugepages[hpage_pmd_order].enabled = SHMEM_INHERIT; - default_settings.shmem_hugepages[anon_order].enabled = SHMEM_ALWAYS; + /* + * Under -o the order-parameterized cases want order-0 sources by + * default; the mixed-source case enables its own (possibly -s + * selected) source order locally. Enabling it globally here would + * make every case fault that order. + */ + if (!anon_target_order) { + default_settings.hugepages[anon_order].enabled = THP_ALWAYS; + default_settings.shmem_hugepages[anon_order].enabled = SHMEM_ALWAYS; + } if (anon_target_order) { /* -- 2.54.0
