Add plugin to trigger kernel plugin

Summary: This plugin triggers kernel panic when executed. This helps capture elusive memory issues which go away after OOM kills.

Reviewed By: masoncl

Differential Revision: D51082682

fbshipit-source-id: 5af584086353ba3fc833dce80dd7959315201af6

docs/core_plugins.md

@@ -125,6 +125,17 @@ otherwise.
 When `negate` is `true`, if `cgroup` doesn't exist, CONTINUE. STOP
 otherwise.
 
+## kernel_panic
+
+### Arguments
+
+    No argument
+
+### Description
+
+This plugin triggers kernel panic when executed, which helps capture elusive
+memory issues that goes away after OOM kills.
+
 ## nr_dying_descendants
 
 ### Arguments

src/oomd/plugins/KernelPanic.cpp

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2018-present, Facebook, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "oomd/plugins/KernelPanic.h"
+
+#include "oomd/Log.h"
+#include "oomd/PluginRegistry.h"
+#include "oomd/util/Fs.h"
+#include "oomd/util/Util.h"
+
+namespace Oomd {
+
+REGISTER_PLUGIN(kernel_panic, KernelPanic::create);
+
+int KernelPanic::init(
+    const Engine::PluginArgs& args,
+    const PluginConstructionContext& /* unused */) {
+  return argParser_.parse(args) ? 0 : 1;
+}
+
+Engine::PluginRet KernelPanic::run(OomdContext& /* unused */) {
+  const auto fd = Fs::Fd::open("/proc/sysrq-trigger", false);
+  if (!fd) {
+    OLOG << "Failed to open /proc/sysrq-trigger";
+    return Engine::PluginRet::CONTINUE;
+  }
+  if (Util::writeFull(fd->fd(), "c", 1) != 1) {
+    OLOG << "Failed to trigger kernel panic";
+    return Engine::PluginRet::CONTINUE;
+  }
+  return Engine::PluginRet::STOP;
+}
+
+} // namespace Oomd

src/oomd/plugins/KernelPanic.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2018-present, Facebook, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include "oomd/engine/BasePlugin.h"
+
+namespace Oomd {
+
+class KernelPanic : public Oomd::Engine::BasePlugin {
+ public:
+  int init(
+      const Engine::PluginArgs& args,
+      const PluginConstructionContext& context) override;
+
+  Engine::PluginRet run(OomdContext& /* unused */) override;
+
+  static KernelPanic* create() {
+    return new KernelPanic();
+  }
+
+  ~KernelPanic() override = default;
+};
+
+} // namespace Oomd