diff --git a/mx_proc.c b/mx_proc.c
index c5197f28..7d402ebc 100644
--- a/mx_proc.c
+++ b/mx_proc.c
@@ -4,10 +4,38 @@
 #include <assert.h>
 #include <dirent.h>
 #include <ctype.h>
+#include <limits.h>
 
 #include "mx_util.h"
 #include "mx_proc.h"
 
+static long long int get_rss_anon(pid_t pid) {
+    _mx_cleanup_free_ char *fname;
+    mx_asprintf_forever(&fname, "/proc/%d/status", pid);
+    _mx_cleanup_fclose_ FILE *file = fopen(fname, "r");
+    if (file == NULL)
+        return -errno;
+    _mx_cleanup_free_ char *buf = NULL;
+    size_t n = 0;
+    while(1) {
+        size_t len = getline(&buf, &n, file);
+        if (len == -1)
+            break;
+        if (strncmp(buf, "RssAnon:", 8) == 0) {
+            unsigned long long int anon_rss_kb = strtoull(buf+8, NULL, 10);
+            if (anon_rss_kb == ULLONG_MAX)
+               return -errno;
+            if (anon_rss_kb > LLONG_MAX/1024) { // anon_rss > 8 EiB
+                return -ERANGE;
+            }
+            return anon_rss_kb*1024;
+        }
+    }
+    if (feof(file))
+        return 0;  /* kernel thread */
+    return -errno;
+}
+
 static int _mx_proc_pid_stat_strscan(char *str, struct mx_proc_pid_stat *pps)
 {
     size_t res = 0;
@@ -94,6 +122,10 @@ int mx_proc_pid_stat(struct mx_proc_pid_stat **pps, pid_t pid)
     res = mx_proc_pid_stat_read(pstat, "/proc/%d/stat", pid);
     if (res < 0)
         return res;
+    long long int rss_anon = get_rss_anon(pid);
+    if (rss_anon < 0)
+        return rss_anon;
+    pstat->rss_anon = rss_anon;
     return 0;
 }
 
diff --git a/mx_proc.h b/mx_proc.h
index 6ae184a8..c9006a9f 100644
--- a/mx_proc.h
+++ b/mx_proc.h
@@ -69,6 +69,8 @@ struct mx_proc_pid_stat {
     unsigned long long int delayacct_blkio_ticks; /* 42 */
     unsigned long long int guest_time;  /* 43 */
     long long int cguest_time;          /* 44 */
+
+    unsigned long long int rss_anon;    /* from /proc/PID/status. may be null (kernel thread). unit: bytes */
 };
 
 int mx_proc_pid_stat_read(struct mx_proc_pid_stat *pps, char *fmt, ...);