selftests/vm: cleanup hugetlb file after mremap test

The hugepage-mremap test will create a file in a hugetlb filesystem.  In
a default 'run_vmtests' run, the file will contain all the hugetlb
pages.  After the test, the file remains and there are no free hugetlb
pages for subsequent tests.  This causes those hugetlb tests to fail.

Change hugepage-mremap to take the name of the hugetlb file as an
argument.  Unlink the file within the test, and just to be sure remove
the file in the run_vmtests script.

Link: https://lkml.kernel.org/r/20220201033459.156944-1-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/vm/hugepage-mremap.c

@@ -3,9 +3,10 @@
  * hugepage-mremap:
  *
  * Example of remapping huge page memory in a user application using the
- * mremap system call.  Code assumes a hugetlbfs filesystem is mounted
- * at './huge'.  The amount of memory used by this test is decided by a command
- * line argument in MBs. If missing, the default amount is 10MB.
+ * mremap system call.  The path to a file in a hugetlbfs filesystem must
+ * be passed as the last argument to this test.  The amount of memory used
+ * by this test in MBs can optionally be passed as an argument.  If no memory
+ * amount is passed, the default amount is 10MB.
  *
  * To make sure the test triggers pmd sharing and goes through the 'unshare'
  * path in the mremap code use 1GB (1024) or more.
@@ -25,7 +26,6 @@
 #define DEFAULT_LENGTH_MB 10UL
 #define MB_TO_BYTES(x) (x * 1024 * 1024)
 
-#define FILE_NAME "huge/hugepagefile"
 #define PROTECTION (PROT_READ | PROT_WRITE | PROT_EXEC)
 #define FLAGS (MAP_SHARED | MAP_ANONYMOUS)
 
@@ -107,17 +107,26 @@ static void register_region_with_uffd(char *addr, size_t len)
 
 int main(int argc, char *argv[])
 {
+	size_t length;
+
+	if (argc != 2 && argc != 3) {
+		printf("Usage: %s [length_in_MB] <hugetlb_file>\n", argv[0]);
+		exit(1);
+	}
+
 	/* Read memory length as the first arg if valid, otherwise fallback to
-	 * the default length. Any additional args are ignored.
+	 * the default length.
 	 */
-	size_t length = argc > 1 ? (size_t)atoi(argv[1]) : 0UL;
+	if (argc == 3)
+		length = argc > 2 ? (size_t)atoi(argv[1]) : 0UL;
 
 	length = length > 0 ? length : DEFAULT_LENGTH_MB;
 	length = MB_TO_BYTES(length);
 
 	int ret = 0;
 
-	int fd = open(FILE_NAME, O_CREAT | O_RDWR, 0755);
+	/* last arg is the hugetlb file name */
+	int fd = open(argv[argc-1], O_CREAT | O_RDWR, 0755);
 
 	if (fd < 0) {
 		perror("Open failed");
@@ -169,5 +178,8 @@ int main(int argc, char *argv[])
 
 	munmap(addr, length);
 
+	close(fd);
+	unlink(argv[argc-1]);
+
 	return ret;
 }

tools/testing/selftests/vm/run_vmtests.sh

@@ -111,13 +111,14 @@ fi
 echo "-----------------------"
 echo "running hugepage-mremap"
 echo "-----------------------"
-./hugepage-mremap 256
+./hugepage-mremap $mnt/huge_mremap
 if [ $? -ne 0 ]; then
 	echo "[FAIL]"
 	exitcode=1
 else
 	echo "[PASS]"
 fi
+rm -f $mnt/huge_mremap
 
 echo "NOTE: The above hugetlb tests provide minimal coverage.  Use"
 echo "      https://github.com/libhugetlbfs/libhugetlbfs.git for"