ovs-vswitchd: Call mlockall() from the daemon, not the parent or monitor.

mlockall(2) says:

       Memory  locks  are not inherited by a child created via fork(2) and are
       automatically removed  (unlocked)  during  an  execve(2)  or  when  the
       process terminates.

which means that --mlockall was ineffective in combination with --detach
or --monitor or both.  Both are used in the most common production
configuration of Open vSwitch, so this means that --mlockall has never been
effective in production.

Signed-off-by: Ben Pfaff <blp@nicira.com>

diff --git a/vswitchd/ovs-vswitchd.c b/vswitchd/ovs-vswitchd.c
index 8ef3b10..6062a40 100644 (file)
--- a/vswitchd/ovs-vswitchd.c
+++ b/vswitchd/ovs-vswitchd.c
@@ -55,6 +55,10 @@
 
 VLOG_DEFINE_THIS_MODULE(vswitchd);
 
+/* --mlockall: If set, locks all process memory into physical RAM, preventing
+ * the kernel from paging any of its memory to disk. */
+static bool want_mlockall;
+
 static unixctl_cb_func ovs_vswitchd_exit;
 
 static char *parse_options(int argc, char *argv[], char **unixctl_path);
@@ -81,6 +85,16 @@ main(int argc, char *argv[])
 
     daemonize_start();
 
+    if (want_mlockall) {
+#ifdef HAVE_MLOCKALL
+        if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
+            VLOG_ERR("mlockall failed: %s", strerror(errno));
+        }
+#else
+        VLOG_ERR("mlockall not supported on this system");
+#endif
+    }
+
     retval = unixctl_server_create(unixctl_path, &unixctl);
     if (retval) {
         exit(EXIT_FAILURE);
@@ -175,13 +189,7 @@ parse_options(int argc, char *argv[], char **unixctl_pathp)
             exit(EXIT_SUCCESS);
 
         case OPT_MLOCKALL:
-#ifdef HAVE_MLOCKALL
-            if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
-                VLOG_ERR("mlockall failed: %s", strerror(errno));
-            }
-#else
-            VLOG_ERR("mlockall not supported on this system");
-#endif
+            want_mlockall = true;
             break;
 
         case OPT_UNIXCTL: