From 214fd2f09ede72ce30378a59f62b98c3b4b4319f Mon Sep 17 00:00:00 2001
From: Sam <sam.saffron@gmail.com>
Date: Thu, 2 Aug 2018 15:01:42 +1000
Subject: [PATCH] FEATURE: ability to turn off transparent huge pages on
 arbitrary programs

---
 image/base/Dockerfile |  6 ++++++
 image/base/thpoff.c   | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)
 create mode 100644 image/base/thpoff.c

diff --git a/image/base/Dockerfile b/image/base/Dockerfile
index 405932e..1a77fab 100644
--- a/image/base/Dockerfile
+++ b/image/base/Dockerfile
@@ -91,6 +91,12 @@ RUN /tmp/install-gifsicle
 ADD install-pngquant /tmp/install-pngquant
 RUN /tmp/install-pngquant
 
+# This tool allows us to disable huge page support for our current process
+# since the flag is preserved through forks and execs it can be used on any
+# process
+ADD thpoff.c /src/thpoff.c
+RUN gcc -o /usr/local/sbin/thpoff /src/thpoff.c && rm /src/thpoff.c
+
 # clean up for docker squash
 RUN   rm -fr /usr/share/man &&\
       rm -fr /usr/share/doc &&\
diff --git a/image/base/thpoff.c b/image/base/thpoff.c
new file mode 100644
index 0000000..3195319
--- /dev/null
+++ b/image/base/thpoff.c
@@ -0,0 +1,39 @@
+// PUBLIC DOMAIN CODE
+//
+// A tiny program that disable transparent huge pages on arbitrary processes
+// thpoff echo 1 : will run echo 1 with SET_THP_DISABLE true on the process
+#include <stdio.h>
+#include <sys/prctl.h>
+#include <unistd.h>
+#include <errno.h>
+
+int main( int argc, char **argv) {
+    if (argc < 2) {
+	fprintf(stderr, "ERROR: expecting at least 1 argument!\n");
+	return -1;
+    }
+    prctl(PR_SET_THP_DISABLE, 1, 0, 0, 0);
+
+    char* newargv[argc];
+    int i;
+
+    newargv[argc-1] = NULL;
+    for (i=1; i<argc; i++) {
+	newargv[i-1] = argv[i];
+    }
+
+    execvp(argv[1], newargv);
+
+    if (errno == ENOENT) {
+	fprintf(stderr, "ERROR: file not found\n");
+	return -1;
+    } else if (errno == EACCES) {
+	fprintf(stderr, "ERROR: can not run file\n");
+	return -1;
+    } else if (errno > 0) {
+	fprintf(stderr, "ERROR: %i errno while attempting to run file\n", errno);
+	return -1;
+    }
+
+    return 0;
+}
-- 
2.25.1