From e7cfa67a0573a3680ce63dfc48121bf6396be45d Mon Sep 17 00:00:00 2001
From: Rajeev Kumar <rajekumar@google.com>
Date: Fri, 5 Oct 2018 12:34:59 -0700
Subject: [PATCH] Read memory stats from /proc/pid/stat file.

(cherry pick from commit 0301683e49ab255769b15469487feaab3466167a)
Bug: 117333340
Test: Manual testing using alloc-stress tool
Merged-In: Ie555933aafa6a6b7aa1dbf5518ebe804376e0afd

Change-Id: I8ab08606dba7de2f65711204453067dbfbdcbdd8
---
 lmkd/lmkd.c     | 75 ++++++++++++++++++++++++++++++++++++++-----------
 lmkd/statslog.h |  3 ++
 2 files changed, 62 insertions(+), 16 deletions(-)

diff --git a/lmkd/lmkd.c b/lmkd/lmkd.c
index 26f4df6bf..d6632a2f8 100644
--- a/lmkd/lmkd.c
+++ b/lmkd/lmkd.c
@@ -984,7 +984,7 @@ static void ctrl_connect_handler(int data __unused, uint32_t events __unused) {
 }
 
 #ifdef LMKD_LOG_STATS
-static void memory_stat_parse_line(char *line, struct memory_stat *mem_st) {
+static void memory_stat_parse_line(char* line, struct memory_stat* mem_st) {
     char key[LINE_MAX + 1];
     int64_t value;
 
@@ -1006,25 +1006,61 @@ static void memory_stat_parse_line(char *line, struct memory_stat *mem_st) {
         mem_st->swap_in_bytes = value;
 }
 
-static int memory_stat_parse(struct memory_stat *mem_st,  int pid, uid_t uid) {
-   FILE *fp;
-   char buf[PATH_MAX];
+static int memory_stat_from_cgroup(struct memory_stat* mem_st, int pid, uid_t uid) {
+    FILE *fp;
+    char buf[PATH_MAX];
 
-   snprintf(buf, sizeof(buf), MEMCG_PROCESS_MEMORY_STAT_PATH, uid, pid);
+    snprintf(buf, sizeof(buf), MEMCG_PROCESS_MEMORY_STAT_PATH, uid, pid);
 
-   fp = fopen(buf, "r");
+    fp = fopen(buf, "r");
 
-   if (fp == NULL) {
-       ALOGE("%s open failed: %s", buf, strerror(errno));
-       return -1;
-   }
+    if (fp == NULL) {
+        ALOGE("%s open failed: %s", buf, strerror(errno));
+        return -1;
+    }
 
-   while (fgets(buf, PAGE_SIZE, fp) != NULL ) {
-       memory_stat_parse_line(buf, mem_st);
-   }
-   fclose(fp);
+    while (fgets(buf, PAGE_SIZE, fp) != NULL) {
+        memory_stat_parse_line(buf, mem_st);
+    }
+    fclose(fp);
 
-   return 0;
+    return 0;
+}
+
+static int memory_stat_from_procfs(struct memory_stat* mem_st, int pid) {
+    char path[PATH_MAX];
+    char buffer[PROC_STAT_BUFFER_SIZE];
+    int fd, ret;
+
+    snprintf(path, sizeof(path), PROC_STAT_FILE_PATH, pid);
+    if ((fd = open(path, O_RDONLY | O_CLOEXEC)) < 0) {
+        ALOGE("%s open failed: %s", path, strerror(errno));
+        return -1;
+    }
+
+    ret = read(fd, buffer, sizeof(buffer));
+    if (ret < 0) {
+        ALOGE("%s read failed: %s", path, strerror(errno));
+        close(fd);
+        return -1;
+    }
+    close(fd);
+
+    // field 10 is pgfault
+    // field 12 is pgmajfault
+    // field 24 is rss_in_pages
+    int64_t pgfault = 0, pgmajfault = 0, rss_in_pages = 0;
+    if (sscanf(buffer,
+               "%*u %*s %*s %*d %*d %*d %*d %*d %*d %" SCNd64 " %*d "
+               "%" SCNd64 " %*d %*u %*u %*d %*d %*d %*d %*d %*d "
+               "%*d %*d %" SCNd64 "",
+               &pgfault, &pgmajfault, &rss_in_pages) != 3) {
+        return -1;
+    }
+    mem_st->pgfault = pgfault;
+    mem_st->pgmajfault = pgmajfault;
+    mem_st->rss_in_bytes = (rss_in_pages * PAGE_SIZE);
+    return 0;
 }
 #endif
 
@@ -1316,7 +1352,11 @@ static int kill_one_process(struct proc* procp) {
 
 #ifdef LMKD_LOG_STATS
     if (enable_stats_log) {
-        memory_stat_parse_result = memory_stat_parse(&mem_st, pid, uid);
+        if (per_app_memcg) {
+            memory_stat_parse_result = memory_stat_from_cgroup(&mem_st, pid, uid);
+        } else {
+            memory_stat_parse_result = memory_stat_from_procfs(&mem_st, pid);
+        }
     }
 #endif
 
@@ -1344,6 +1384,9 @@ static int kill_one_process(struct proc* procp) {
             stats_write_lmk_kill_occurred(log_ctx, LMK_KILL_OCCURRED, uid, taskname,
                     procp->oomadj, mem_st.pgfault, mem_st.pgmajfault, mem_st.rss_in_bytes,
                     mem_st.cache_in_bytes, mem_st.swap_in_bytes);
+        } else if (enable_stats_log) {
+            stats_write_lmk_kill_occurred(log_ctx, LMK_KILL_OCCURRED, uid, taskname, procp->oomadj,
+                                          -1, -1, tasksize * BYTES_IN_KILOBYTE, -1, -1);
         }
 #endif
         result = tasksize;
diff --git a/lmkd/statslog.h b/lmkd/statslog.h
index edebb195b..84584805d 100644
--- a/lmkd/statslog.h
+++ b/lmkd/statslog.h
@@ -67,6 +67,9 @@ struct memory_stat {
 };
 
 #define MEMCG_PROCESS_MEMORY_STAT_PATH "/dev/memcg/apps/uid_%u/pid_%u/memory.stat"
+#define PROC_STAT_FILE_PATH "/proc/%d/stat"
+#define PROC_STAT_BUFFER_SIZE 1024
+#define BYTES_IN_KILOBYTE 1024
 
 /**
  * Logs the change in LMKD state which is used as start/stop boundaries for logging