commit 2018bf03f9fd96aa0326d74f23abdbaa3d4ee143
author Suren Baghdasaryan <surenb@google.com> Wed Dec 18 09:52:42 2019 -0800
committer Suren Baghdasaryan <surenb@google.com> Thu Jan 02 13:36:34 2020 -0800
tree 6fd16205a305b31a8a5b60c6f7eb23c6df1d7b68
parent 5a049f5cf22d2eb5c7c4974fbf282427cb418ece

Prevent double-counting of kernel stack size in dumpsys reports

When kernel is configured with CONFIG_VMAP_STACK=y kernel stacks are mapped
into process space and therefore already accounted as part of the value
returned by ReadVmallocInfo and reported under MEMINFO_VM_ALLOC_USED
category. Introduce isVmapStack function to check if kernel is configured
with that option and if so do not exclude kernel stack size in the
calculation of memory used by kernel.

Bug: 146088882
Test: dumpsys meminfo with CONFIG_VMAP_STACK enabled and disabled
Change-Id: I9230bbf0ab05524cf52ded35171fd9ec3da16fa0
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

core/java/android/os/Debug.java

diff --git a/core/java/android/os/Debug.java b/core/java/android/os/Debug.java
index 422761c..d7ed055 100644
--- a/core/java/android/os/Debug.java
+++ b/core/java/android/os/Debug.java
@@ -2526,4 +2526,12 @@
      * @hide
      */
     public static native long getIonMappedSizeKb();
+
+    /**
+     * Return whether virtually-mapped kernel stacks are enabled (CONFIG_VMAP_STACK).
+     * Note: caller needs config_gz read sepolicy permission
+     *
+     * @hide
+     */
+    public static native boolean isVmapStack();
 }

core/java/com/android/internal/util/MemInfoReader.java

diff --git a/core/java/com/android/internal/util/MemInfoReader.java b/core/java/com/android/internal/util/MemInfoReader.java
index 362bc92..580c2fa 100644
--- a/core/java/com/android/internal/util/MemInfoReader.java
+++ b/core/java/com/android/internal/util/MemInfoReader.java
@@ -107,9 +107,12 @@
      * Amount of RAM that is in use by the kernel for actual allocations.
      */
     public long getKernelUsedSizeKb() {
-        return mInfos[Debug.MEMINFO_SHMEM] + mInfos[Debug.MEMINFO_SLAB_UNRECLAIMABLE]
-                + mInfos[Debug.MEMINFO_VM_ALLOC_USED] + mInfos[Debug.MEMINFO_PAGE_TABLES]
-                + mInfos[Debug.MEMINFO_KERNEL_STACK];
+        long size = mInfos[Debug.MEMINFO_SHMEM] + mInfos[Debug.MEMINFO_SLAB_UNRECLAIMABLE]
+                + mInfos[Debug.MEMINFO_VM_ALLOC_USED] + mInfos[Debug.MEMINFO_PAGE_TABLES];
+        if (!Debug.isVmapStack()) {
+            size += mInfos[Debug.MEMINFO_KERNEL_STACK];
+        }
+        return size;
     }
 
     public long getSwapTotalSizeKb() {

core/jni/android_os_Debug.cpp

diff --git a/core/jni/android_os_Debug.cpp b/core/jni/android_os_Debug.cpp
index 3e7b6b3..52ce54b 100644
--- a/core/jni/android_os_Debug.cpp
+++ b/core/jni/android_os_Debug.cpp
@@ -50,6 +50,7 @@
 #include <memunreachable/memunreachable.h>
 #include <android-base/strings.h>
 #include "android_os_Debug.h"
+#include <vintf/VintfObject.h>
 
 namespace android
 {
@@ -833,6 +834,23 @@
     return ionPss;
 }
 
+static jboolean android_os_Debug_isVmapStack(JNIEnv *env, jobject clazz)
+{
+    static enum {
+        CONFIG_UNKNOWN,
+        CONFIG_SET,
+        CONFIG_UNSET,
+    } cfg_state = CONFIG_UNKNOWN;
+
+    if (cfg_state == CONFIG_UNKNOWN) {
+        const std::map<std::string, std::string> configs =
+            vintf::VintfObject::GetInstance()->getRuntimeInfo()->kernelConfigs();
+        std::map<std::string, std::string>::const_iterator it = configs.find("CONFIG_VMAP_STACK");
+        cfg_state = (it != configs.end() && it->second == "y") ? CONFIG_SET : CONFIG_UNSET;
+    }
+    return cfg_state == CONFIG_SET;
+}
+
 /*
  * JNI registration.
  */
@@ -882,6 +900,8 @@
             (void*)android_os_Debug_getIonPoolsSizeKb },
     { "getIonMappedSizeKb", "()J",
             (void*)android_os_Debug_getIonMappedSizeKb },
+    { "isVmapStack", "()Z",
+            (void*)android_os_Debug_isVmapStack },
 };
 
 int register_android_os_Debug(JNIEnv *env)