selftests/mm: drop sys/dev test in uffd-stress test

With the new uffd unit test covering the /dev/userfaultfd path and syscall
path of uffd initializations, we can safely drop the devnode test in the
old stress test.

One thing is to avoid duplication of running the stress test twice which is
an overkill to only test the /dev/ interface in run_vmtests.sh.

The other benefit is now all uffd tests (that uses userfaultfd_open) can
run automatically as long as any type of interface is enabled (either
syscall or dev), so it's more likely to succeed rather than fail due to
unprivilege.

With this patch lands, we can drop all the "mem_type:XXX" handlings too.

Link: https://lkml.kernel.org/r/20230412164525.329176-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/run_vmtests.sh

@@ -197,16 +197,13 @@ CATEGORY="gup_test" run_test ./gup_test -a
 CATEGORY="gup_test" run_test ./gup_test -ct -F 0x1 0 19 0x1000
 
 CATEGORY="userfaultfd" run_test ./uffd-unit-tests
-uffd_mods=("" ":dev")
 uffd_stress_bin=./uffd-stress
-for mod in "${uffd_mods[@]}"; do
-	CATEGORY="userfaultfd" run_test ${uffd_stress_bin} anon${mod} 20 16
-	# Hugetlb tests require source and destination huge pages. Pass in half
-	# the size ($half_ufd_size_MB), which is used for *each*.
-	CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb${mod} "$half_ufd_size_MB" 32
-	CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb_shared${mod} "$half_ufd_size_MB" 32
-	CATEGORY="userfaultfd" run_test ${uffd_stress_bin} shmem${mod} 20 16
-done
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} anon 20 16
+# Hugetlb tests require source and destination huge pages. Pass in half
+# the size ($half_ufd_size_MB), which is used for *each*.
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb "$half_ufd_size_MB" 32
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb_shared "$half_ufd_size_MB" 32
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} shmem 20 16
 
 #cleanup
 echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages

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

@@ -13,7 +13,7 @@ volatile bool test_uffdio_copy_eexist = true;
 unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size;
 char *area_src, *area_src_alias, *area_dst, *area_dst_alias, *area_remap;
 int uffd = -1, uffd_flags, finished, *pipefd, test_type;
-bool map_shared, test_dev_userfaultfd;
+bool map_shared;
 bool test_uffdio_wp = true;
 unsigned long long *count_verify;
 uffd_test_ops_t *uffd_test_ops;
@@ -236,10 +236,7 @@ int userfaultfd_open(uint64_t *features)
 {
 	struct uffdio_api uffdio_api;
 
-	if (test_dev_userfaultfd)
-		uffd = uffd_open_dev(UFFD_FLAGS);
-	else
-		uffd = uffd_open_sys(UFFD_FLAGS);
+	uffd = uffd_open(UFFD_FLAGS);
 	if (uffd < 0)
 		return -1;
 	uffd_flags = fcntl(uffd, F_GETFD, NULL);

tools/testing/selftests/mm/uffd-common.h

@@ -90,7 +90,7 @@ typedef struct uffd_test_ops uffd_test_ops_t;
 extern unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size;
 extern char *area_src, *area_src_alias, *area_dst, *area_dst_alias, *area_remap;
 extern int uffd, uffd_flags, finished, *pipefd, test_type;
-extern bool map_shared, test_dev_userfaultfd;
+extern bool map_shared;
 extern bool test_uffdio_wp;
 extern unsigned long long *count_verify;
 extern volatile bool test_uffdio_copy_eexist;

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

@@ -55,8 +55,6 @@ pthread_attr_t attr;
 const char *examples =
     "# Run anonymous memory test on 100MiB region with 99999 bounces:\n"
     "./userfaultfd anon 100 99999\n\n"
-    "# Run the same anonymous memory test, but using /dev/userfaultfd:\n"
-    "./userfaultfd anon:dev 100 99999\n\n"
     "# Run share memory test on 1GiB region with 99 bounces:\n"
     "./userfaultfd shmem 1000 99\n\n"
     "# Run hugetlb memory test on 256MiB region with 50 bounces:\n"
@@ -69,18 +67,9 @@ const char *examples =
 
 static void usage(void)
 {
-	fprintf(stderr, "\nUsage: ./userfaultfd <test type> <MiB> <bounces> "
-		"[hugetlbfs_file]\n\n");
+	fprintf(stderr, "\nUsage: ./userfaultfd <test type> <MiB> <bounces>\n\n");
 	fprintf(stderr, "Supported <test type>: anon, hugetlb, "
 		"hugetlb_shared, shmem\n\n");
-	fprintf(stderr, "'Test mods' can be joined to the test type string with a ':'. "
-		"Supported mods:\n");
-	fprintf(stderr, "\tsyscall - Use userfaultfd(2) (default)\n");
-	fprintf(stderr, "\tdev - Use /dev/userfaultfd instead of userfaultfd(2)\n");
-	fprintf(stderr, "\nExample test mod usage:\n");
-	fprintf(stderr, "# Run anonymous memory test with /dev/userfaultfd:\n");
-	fprintf(stderr, "./userfaultfd anon:dev 100 99999\n\n");
-
 	fprintf(stderr, "Examples:\n\n");
 	fprintf(stderr, "%s", examples);
 	exit(1);
@@ -400,21 +389,9 @@ static void set_test_type(const char *type)
 
 static void parse_test_type_arg(const char *raw_type)
 {
-	char *buf = strdup(raw_type);
 	uint64_t features = UFFD_API_FEATURES;
 
-	while (buf) {
-		const char *token = strsep(&buf, ":");
-
-		if (!test_type)
-			set_test_type(token);
-		else if (!strcmp(token, "dev"))
-			test_dev_userfaultfd = true;
-		else if (!strcmp(token, "syscall"))
-			test_dev_userfaultfd = false;
-		else
-			err("unrecognized test mod '%s'", token);
-	}
+	set_test_type(raw_type);
 
 	if (!test_type)
 		err("failed to parse test type argument: '%s'", raw_type);