From 0301683e49ab255769b15469487feaab3466167a 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.

Bug: 117333340
Test: Manual testing using alloc-stress tool
Change-Id: Ie555933aafa6a6b7aa1dbf5518ebe804376e0afd
---
 lmkd/lmkd.c     | 59 ++++++++++++++++++++++++++++++++++++++++---------
 lmkd/statslog.h |  3 +++
 2 files changed, 51 insertions(+), 11 deletions(-)

diff --git a/lmkd/lmkd.c b/lmkd/lmkd.c
index 1980dc660..8b68dcad2 100644
--- a/lmkd/lmkd.c
+++ b/lmkd/lmkd.c
@@ -822,7 +822,7 @@ 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;
 
@@ -844,17 +844,10 @@ 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) {
+static int memory_stat_from_cgroup(struct memory_stat* mem_st, int pid, uid_t uid) {
     FILE *fp;
     char buf[PATH_MAX];
 
-    /*
-     * Per-application memory.stat files are available only when
-     * per-application memcgs are enabled.
-     */
-    if (!per_app_memcg)
-        return -1;
-
     snprintf(buf, sizeof(buf), MEMCG_PROCESS_MEMORY_STAT_PATH, uid, pid);
 
     fp = fopen(buf, "r");
@@ -864,13 +857,50 @@ static int memory_stat_parse(struct memory_stat *mem_st,  int pid, uid_t uid) {
         return -1;
     }
 
-    while (fgets(buf, PAGE_SIZE, fp) != NULL ) {
+    while (fgets(buf, PAGE_SIZE, fp) != NULL) {
         memory_stat_parse_line(buf, mem_st);
     }
     fclose(fp);
 
     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
 
 /* /prop/zoneinfo parsing routines */
@@ -1125,7 +1155,11 @@ 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
 
@@ -1148,6 +1182,9 @@ 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
         return 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