Commit 1580cd50 authored by Dev Jain's avatar Dev Jain Committed by Andrew Morton
Browse files

selftests/mm/uffd-stress: stricten constraint on free hugepages needed before the test 

The test requires at least 2 * (bytes/page_size) hugetlb memory, since we
require identical number of hugepages for src and dst location.  Fix this.

Along with the above, as explained in patch "selftests/mm/uffd-stress:
Make test operate on less hugetlb memory", the racy nature of the test
requires that we have some extra number of hugepages left beyond what is
required.  Therefore, stricten this constraint.

Link: https://lkml.kernel.org/r/20250909061531.57272-3-dev.jain@arm.com


Fixes: 5a6aa60d ("selftests/mm: skip uffd hugetlb tests with insufficient hugepages")
Signed-off-by: default avatarDev Jain <dev.jain@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 060b6c72

tools/testing/selftests/mm/uffd-stress.c

+11 −6
Original line number Diff line number Diff line
@@ -448,12 +448,6 @@ int main(int argc, char **argv) 
	parse_test_type_arg(argv[1]);

	bytes = atol(argv[2]) * 1024 * 1024;



	if (test_type == TEST_HUGETLB &&

	   get_free_hugepages() < bytes / page_size) {

		printf("skip: Skipping userfaultfd... not enough hugepages\n");

		return KSFT_SKIP;

	}



	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);

	if (nr_cpus > 32) {

		/* Don't let calculation below go to zero. */
@@ -464,6 +458,17 @@ int main(int argc, char **argv) 
		nr_parallel = nr_cpus;

	}



	/*

	 * src and dst each require bytes / page_size number of hugepages.

	 * Ensure nr_parallel - 1 hugepages on top of that to account

	 * for racy extra reservation of hugepages.

	 */

	if (test_type == TEST_HUGETLB &&

	   get_free_hugepages() < 2 * (bytes / page_size) + nr_parallel - 1) {

		printf("skip: Skipping userfaultfd... not enough hugepages\n");

		return KSFT_SKIP;

	}



	nr_pages_per_cpu = bytes / page_size / nr_parallel;

	if (!nr_pages_per_cpu) {

		_err("pages_per_cpu = 0, cannot test (%lu / %lu / %lu)",