/run/shm is the general replacement for /dev/shm in newer distros

mysql-test/mysql-test-run.pl

@@ -1462,7 +1462,7 @@ sub command_line_setup {
     # Search through list of locations that are known
     # to be "fast disks" to find a suitable location
     # Use --mem=<dir> as first location to look.
-    my @tmpfs_locations= ($opt_mem, "/dev/shm", "/tmp");
+    my @tmpfs_locations= ($opt_mem,"/run/shm", "/dev/shm", "/tmp");
 
     foreach my $fs (@tmpfs_locations)
     {
@@ -6367,7 +6367,7 @@ Options to control directories to use
   mem                   Run testsuite in "memory" using tmpfs or ramdisk
                         Attempts to find a suitable location
                         using a builtin list of standard locations
-                        for tmpfs (/dev/shm)
+                        for tmpfs (/run/shm, /dev/shm, /tmp)
                         The option can also be set using environment
                         variable MTR_MEM=[DIR]
   clean-vardir          Clean vardir if tests were successful and if