diff --git a/tools/testing/selftests/mm/gup_longterm.c b/tools/testing/selftests/mm/gup_longterm.c
index 03271442aae5..21595b20bbc3 100644
--- a/tools/testing/selftests/mm/gup_longterm.c
+++ b/tools/testing/selftests/mm/gup_longterm.c
@@ -97,11 +97,7 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
 
 	if (ftruncate(fd, size)) {
 		if (errno == ENOENT) {
-			/*
-			 * This can happen if the file has been unlinked and the
-			 * filesystem doesn't support truncating unlinked files.
-			 */
-			ksft_test_result_skip("ftruncate() failed with ENOENT\n");
+			skip_test_dodgy_fs("ftruncate()");
 		} else {
 			ksft_test_result_fail("ftruncate() failed (%s)\n", strerror(errno));
 		}
diff --git a/tools/testing/selftests/mm/map_populate.c b/tools/testing/selftests/mm/map_populate.c
index 433e54fb634f..9df2636c829b 100644
--- a/tools/testing/selftests/mm/map_populate.c
+++ b/tools/testing/selftests/mm/map_populate.c
@@ -18,6 +18,8 @@
 #include <unistd.h>
 #include "../kselftest.h"
 
+#include "vm_util.h"
+
 #define MMAP_SZ		4096
 
 #define BUG_ON(condition, description)						\
@@ -88,11 +90,7 @@ int main(int argc, char **argv)
 
 	ret = ftruncate(fileno(ftmp), MMAP_SZ);
 	if (ret < 0 && errno == ENOENT) {
-		/*
-		 * This probably means tmpfile() made a file on a filesystem
-		 * that doesn't handle temporary files the way we want.
-		 */
-		ksft_exit_skip("ftruncate(fileno(tmpfile())) gave ENOENT, weird filesystem?\n");
+		skip_test_dodgy_fs("ftruncate()");
 	}
 	BUG_ON(ret, "ftruncate()");
 
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 0e629586556b..6effafdc4d8a 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -5,6 +5,7 @@
 #include <err.h>
 #include <strings.h> /* ffsl() */
 #include <unistd.h> /* _SC_PAGESIZE */
+#include "../kselftest.h"
 
 #define BIT_ULL(nr)                   (1ULL << (nr))
 #define PM_SOFT_DIRTY                 BIT_ULL(55)
@@ -32,6 +33,23 @@ static inline unsigned int pshift(void)
 	return __page_shift;
 }
 
+/*
+ * Plan 9 FS has bugs (at least on QEMU) where certain operations fail with
+ * ENOENT on unlinked files. See
+ * https://gitlab.com/qemu-project/qemu/-/issues/103 for some info about such
+ * bugs. There are rumours of NFS implementations with similar bugs.
+ *
+ * Ideally, tests should just detect filesystems known to have such issues and
+ * bail early. But 9pfs has the additional "feature" that it causes fstatfs to
+ * pass through the f_type field from the host filesystem. To avoid having to
+ * scrape /proc/mounts or some other hackery, tests can call this function when
+ * it seems such a bug might have been encountered.
+ */
+static inline void skip_test_dodgy_fs(const char *op_name)
+{
+	ksft_test_result_skip("%s failed with ENOENT. Filesystem might be buggy (9pfs?)\n", op_name);
+}
+
 uint64_t pagemap_get_entry(int fd, char *start);
 bool pagemap_is_softdirty(int fd, char *start);
 bool pagemap_is_swapped(int fd, char *start);