From 721d7c7fa31315fcb0483eb4400278bcc80cd9ad Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn@google.com>
Date: Wed, 21 Mar 2018 12:24:58 -0700
Subject: [PATCH] lmkd: only mlockall() if enabled

Move process initialization, mlockall() and sched_setscheduler() to
only occur if initialization succeeds and is enabled.  This
conserves mlock'd memory and a FIFO processing slot if (deprecated)
kernel lowmemorykiller is active.

Cleanup: Android coding standard compliance.

Test: lmkd_unit_test
Bug: 33808187
Bug: 72838192
Change-Id: I51af0235c8eca4ef958ef2d83a8071ff58b49d78
---
 lmkd/Android.bp |  2 +-
 lmkd/lmkd.c     | 43 ++++++++++++++++++++++++++-----------------
 2 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/lmkd/Android.bp b/lmkd/Android.bp
index d172755bd..2efda86cd 100644
--- a/lmkd/Android.bp
+++ b/lmkd/Android.bp
@@ -3,8 +3,8 @@ cc_binary {
 
     srcs: ["lmkd.c"],
     shared_libs: [
-        "liblog",
         "libcutils",
+        "liblog",
     ],
     local_include_dirs: ["include"],
     cflags: ["-Werror"],
diff --git a/lmkd/lmkd.c b/lmkd/lmkd.c
index 72f9f7b24..f7c90ec0b 100644
--- a/lmkd/lmkd.c
+++ b/lmkd/lmkd.c
@@ -29,8 +29,8 @@
 #include <sys/eventfd.h>
 #include <sys/mman.h>
 #include <sys/socket.h>
-#include <sys/types.h>
 #include <sys/sysinfo.h>
+#include <sys/types.h>
 #include <unistd.h>
 
 #include <cutils/properties.h>
@@ -77,7 +77,7 @@
 #define SYSTEM_ADJ (-900)
 
 /* default to old in-kernel interface if no memory pressure events */
-static int use_inkernel_interface = 1;
+static bool use_inkernel_interface = true;
 static bool has_inkernel_module;
 
 /* memory pressure levels */
@@ -326,8 +326,9 @@ static void cmd_procprio(LMKD_CTRL_PACKET packet) {
         return;
     }
 
-    if (use_inkernel_interface)
+    if (use_inkernel_interface) {
         return;
+    }
 
     if (params.oomadj >= 900) {
         soft_limit_mult = 0;
@@ -393,8 +394,9 @@ static void cmd_procprio(LMKD_CTRL_PACKET packet) {
 static void cmd_procremove(LMKD_CTRL_PACKET packet) {
     struct lmk_procremove params;
 
-    if (use_inkernel_interface)
+    if (use_inkernel_interface) {
         return;
+    }
 
     lmkd_pack_get_procremove(packet, &params);
     pid_remove(params.pid);
@@ -1205,21 +1207,28 @@ int main(int argc __unused, char **argv __unused) {
     kill_timeout_ms =
         (unsigned long)property_get_int32("ro.lmk.kill_timeout_ms", 0);
 
-    // MCL_ONFAULT pins pages as they fault instead of loading
-    // everything immediately all at once. (Which would be bad,
-    // because as of this writing, we have a lot of mapped pages we
-    // never use.) Old kernels will see MCL_ONFAULT and fail with
-    // EINVAL; we ignore this failure.
-    //
-    // N.B. read the man page for mlockall. MCL_CURRENT | MCL_ONFAULT
-    // pins ⊆ MCL_CURRENT, converging to just MCL_CURRENT as we fault
-    // in pages.
-    if (mlockall(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT) && errno != EINVAL)
-        ALOGW("mlockall failed: errno=%d", errno);
+    if (!init()) {
+        if (!use_inkernel_interface) {
+            /*
+             * MCL_ONFAULT pins pages as they fault instead of loading
+             * everything immediately all at once. (Which would be bad,
+             * because as of this writing, we have a lot of mapped pages we
+             * never use.) Old kernels will see MCL_ONFAULT and fail with
+             * EINVAL; we ignore this failure.
+             *
+             * N.B. read the man page for mlockall. MCL_CURRENT | MCL_ONFAULT
+             * pins ⊆ MCL_CURRENT, converging to just MCL_CURRENT as we fault
+             * in pages.
+             */
+            if (mlockall(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT) && (errno != EINVAL)) {
+                ALOGW("mlockall failed %s", strerror(errno));
+            }
+
+            sched_setscheduler(0, SCHED_FIFO, &param);
+        }
 
-    sched_setscheduler(0, SCHED_FIFO, &param);
-    if (!init())
         mainloop();
+    }
 
     ALOGI("exiting");
     return 0;