From 5a07333894bd9de77d5874b16d16129ef5847956 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Mon, 25 Jan 2021 15:30:03 +0000
Subject: [PATCH 01/20] src: simplify kernel transparent_hugepage enabled flag
 check by removing while loop

There was an unexpected and hard-to-spot issue here: the /sys/kernel/mm/transparent_hugepage/enabled file contains three entries, and the std::ifstream reader was reading two values on each loop iteration, resulting in incorrect behaviour.
---
 src/large_pages/node_large_page.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index a4b109d1b0ef69..bb467b6902b459 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -268,7 +268,7 @@ bool IsTransparentHugePagesEnabled() {
 
   std::string always, madvise;
   if (ifs.is_open()) {
-    while (ifs >> always >> madvise) {}
+    ifs >> always >> madvise;
   }
   ifs.close();
 

From 72082b9956c6b360cf2b27107a36ba307cf3c2b3 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Tue, 26 Jan 2021 15:11:00 +0000
Subject: [PATCH 02/20] src: inspect kernel transparent_hugepage flag values
 without assuming their length or ordering

---
 src/large_pages/node_large_page.cc | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index bb467b6902b459..3c984322d4fa57 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -266,13 +266,16 @@ bool IsTransparentHugePagesEnabled() {
     return false;
   }
 
-  std::string always, madvise;
+  bool enabled;
   if (ifs.is_open()) {
-    ifs >> always >> madvise;
+    std::string token;
+    while (ifs >> token) {
+      enabled = enabled || token == "[always]" || token == "[madvise]";
+    }
   }
   ifs.close();
 
-  return always == "[always]" || madvise == "[madvise]";
+  return enabled;
 }
 #elif defined(__FreeBSD__)
 bool IsSuperPagesEnabled() {

From 53648a00b20d7d39042e1695aab0313e7dbf89b7 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Tue, 26 Jan 2021 16:25:26 +0000
Subject: [PATCH 03/20] src: add an explicit default value for the 'enabled'
 bool variable

Co-authored-by: Darshan Sen <raisinten@gmail.com>
---
 src/large_pages/node_large_page.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 3c984322d4fa57..e72c55310f2db3 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -266,7 +266,7 @@ bool IsTransparentHugePagesEnabled() {
     return false;
   }
 
-  bool enabled;
+  bool enabled = false;
   if (ifs.is_open()) {
     std::string token;
     while (ifs >> token) {

From a7fe1932a49685bd388917ec3e7c68325d123fb3 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Tue, 26 Jan 2021 16:24:29 +0000
Subject: [PATCH 04/20] src: extract GetTransparentHugePagesConfiguration
 function to read system huge tables configuration on Linux-based systems

---
 src/large_pages/node_large_page.cc | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index e72c55310f2db3..789fbc6b93e1f1 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -257,24 +257,30 @@ struct text_region FindNodeTextRegion() {
 }
 
 #if defined(__linux__)
-bool IsTransparentHugePagesEnabled() {
-  std::ifstream ifs;
+std::istream *GetTransparentHugePagesConfiguration() {
+  std::ifstream *ifs = new std::ifstream();
 
-  ifs.open("/sys/kernel/mm/transparent_hugepage/enabled");
-  if (!ifs) {
+  ifs->open("/sys/kernel/mm/transparent_hugepage/enabled");
+  if (!*ifs) {
     PrintWarning("could not open /sys/kernel/mm/transparent_hugepage/enabled");
+    return nullptr;
+  }
+
+  return ifs;
+}
+
+bool IsTransparentHugePagesEnabled() {
+  std::istream *configuration = GetTransparentHugePagesConfiguration();
+  if (configuration == nullptr) {
     return false;
   }
 
   bool enabled = false;
-  if (ifs.is_open()) {
-    std::string token;
-    while (ifs >> token) {
-      enabled = enabled || token == "[always]" || token == "[madvise]";
-    }
+  std::string token;
+  while (*configuration >> token) {
+    enabled = enabled || token == "[always]" || token == "[madvise]";
   }
-  ifs.close();
-
+  delete configuration;
   return enabled;
 }
 #elif defined(__FreeBSD__)

From 72dd2f3c8336d49333f252f73d20e9ac732838bc Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Tue, 26 Jan 2021 16:36:57 +0000
Subject: [PATCH 05/20] src: extract
 IsTransparentHugePagesEnabledViaConfiguration function to determine huge
 tables enabled state based on the contents of a configuration stream

---
 src/large_pages/node_large_page.cc | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 789fbc6b93e1f1..75e3640579e152 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -269,17 +269,21 @@ std::istream *GetTransparentHugePagesConfiguration() {
   return ifs;
 }
 
-bool IsTransparentHugePagesEnabled() {
-  std::istream *configuration = GetTransparentHugePagesConfiguration();
-  if (configuration == nullptr) {
-    return false;
-  }
-
+bool IsTransparentHugePagesEnabledViaConfiguration(std::istream *configuration) {
   bool enabled = false;
   std::string token;
   while (*configuration >> token) {
     enabled = enabled || token == "[always]" || token == "[madvise]";
   }
+  return enabled;
+}
+
+bool IsTransparentHugePagesEnabled() {
+  std::istream *configuration = GetTransparentHugePagesConfiguration();
+  if (configuration == nullptr) {
+    return false;
+  }
+  bool enabled = IsTransparentHugePagesEnabledViaConfiguration(configuration);
   delete configuration;
   return enabled;
 }

From 519f21264b2430956da866d4cf20bd9f20c78ce4 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Tue, 26 Jan 2021 16:38:53 +0000
Subject: [PATCH 06/20] src: refactor: return early when we discover that huge
 tables is enabled in the configuration stream

---
 src/large_pages/node_large_page.cc | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 75e3640579e152..d809217a17d18f 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -270,12 +270,11 @@ std::istream *GetTransparentHugePagesConfiguration() {
 }
 
 bool IsTransparentHugePagesEnabledViaConfiguration(std::istream *configuration) {
-  bool enabled = false;
   std::string token;
   while (*configuration >> token) {
-    enabled = enabled || token == "[always]" || token == "[madvise]";
+    if (token == "[always]" || token == "[madvise]") return true;
   }
-  return enabled;
+  return false;
 }
 
 bool IsTransparentHugePagesEnabled() {

From 21ed800d050e1296cd495cb065bd379fe3e54324 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Tue, 26 Jan 2021 18:47:27 +0000
Subject: [PATCH 07/20] src: apply lint fix: use left-leaning pointers

---
 src/large_pages/node_large_page.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index d809217a17d18f..a624356823a95b 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -257,8 +257,8 @@ struct text_region FindNodeTextRegion() {
 }
 
 #if defined(__linux__)
-std::istream *GetTransparentHugePagesConfiguration() {
-  std::ifstream *ifs = new std::ifstream();
+std::istream* GetTransparentHugePagesConfiguration() {
+  std::ifstream* ifs = new std::ifstream();
 
   ifs->open("/sys/kernel/mm/transparent_hugepage/enabled");
   if (!*ifs) {
@@ -269,7 +269,7 @@ std::istream *GetTransparentHugePagesConfiguration() {
   return ifs;
 }
 
-bool IsTransparentHugePagesEnabledViaConfiguration(std::istream *configuration) {
+bool IsTransparentHugePagesEnabledViaConfiguration(std::istream* configuration) {
   std::string token;
   while (*configuration >> token) {
     if (token == "[always]" || token == "[madvise]") return true;
@@ -278,7 +278,7 @@ bool IsTransparentHugePagesEnabledViaConfiguration(std::istream *configuration)
 }
 
 bool IsTransparentHugePagesEnabled() {
-  std::istream *configuration = GetTransparentHugePagesConfiguration();
+  std::istream* configuration = GetTransparentHugePagesConfiguration();
   if (configuration == nullptr) {
     return false;
   }

From 03922c01e00676fe480c33b75476488b847db6a4 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Tue, 26 Jan 2021 18:48:25 +0000
Subject: [PATCH 08/20] src: lint fixup: rename function to fit within column
 width constraint

---
 src/large_pages/node_large_page.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index a624356823a95b..550ab70c2119eb 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -269,7 +269,7 @@ std::istream* GetTransparentHugePagesConfiguration() {
   return ifs;
 }
 
-bool IsTransparentHugePagesEnabledViaConfiguration(std::istream* configuration) {
+bool IsTransparentHugePagesConfigured(std::istream* configuration) {
   std::string token;
   while (*configuration >> token) {
     if (token == "[always]" || token == "[madvise]") return true;
@@ -282,7 +282,7 @@ bool IsTransparentHugePagesEnabled() {
   if (configuration == nullptr) {
     return false;
   }
-  bool enabled = IsTransparentHugePagesEnabledViaConfiguration(configuration);
+  bool enabled = IsTransparentHugePagesConfigured(configuration);
   delete configuration;
   return enabled;
 }

From 434e8b8bba8554d89867fb7a54a035f99ed1f58a Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Tue, 26 Jan 2021 20:43:00 +0000
Subject: [PATCH 09/20] src: use single-line return statement for null-pointer
 condition

---
 src/large_pages/node_large_page.cc | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 550ab70c2119eb..c7e5541ac6a1a3 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -279,9 +279,7 @@ bool IsTransparentHugePagesConfigured(std::istream* configuration) {
 
 bool IsTransparentHugePagesEnabled() {
   std::istream* configuration = GetTransparentHugePagesConfiguration();
-  if (configuration == nullptr) {
-    return false;
-  }
+  if (configuration == nullptr) return false;
   bool enabled = IsTransparentHugePagesConfigured(configuration);
   delete configuration;
   return enabled;

From 49b35e9a09cfd495c5cfc5f295ca9091b659fbe8 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:33:47 +0000
Subject: [PATCH 10/20] Revert "src: use single-line return statement for
 null-pointer condition"

This reverts commit 434e8b8bba8554d89867fb7a54a035f99ed1f58a.
---
 src/large_pages/node_large_page.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index c7e5541ac6a1a3..550ab70c2119eb 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -279,7 +279,9 @@ bool IsTransparentHugePagesConfigured(std::istream* configuration) {
 
 bool IsTransparentHugePagesEnabled() {
   std::istream* configuration = GetTransparentHugePagesConfiguration();
-  if (configuration == nullptr) return false;
+  if (configuration == nullptr) {
+    return false;
+  }
   bool enabled = IsTransparentHugePagesConfigured(configuration);
   delete configuration;
   return enabled;

From 24d49431f6eb680fcdaef07b7c98b905dad6edf5 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:33:53 +0000
Subject: [PATCH 11/20] Revert "src: lint fixup: rename function to fit within
 column width constraint"

This reverts commit 03922c01e00676fe480c33b75476488b847db6a4.
---
 src/large_pages/node_large_page.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 550ab70c2119eb..a624356823a95b 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -269,7 +269,7 @@ std::istream* GetTransparentHugePagesConfiguration() {
   return ifs;
 }
 
-bool IsTransparentHugePagesConfigured(std::istream* configuration) {
+bool IsTransparentHugePagesEnabledViaConfiguration(std::istream* configuration) {
   std::string token;
   while (*configuration >> token) {
     if (token == "[always]" || token == "[madvise]") return true;
@@ -282,7 +282,7 @@ bool IsTransparentHugePagesEnabled() {
   if (configuration == nullptr) {
     return false;
   }
-  bool enabled = IsTransparentHugePagesConfigured(configuration);
+  bool enabled = IsTransparentHugePagesEnabledViaConfiguration(configuration);
   delete configuration;
   return enabled;
 }

From 250e0138cbf4f097e5524cb450df3e257fceef10 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:34:09 +0000
Subject: [PATCH 12/20] Revert "src: apply lint fix: use left-leaning pointers"

This reverts commit 21ed800d050e1296cd495cb065bd379fe3e54324.
---
 src/large_pages/node_large_page.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index a624356823a95b..d809217a17d18f 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -257,8 +257,8 @@ struct text_region FindNodeTextRegion() {
 }
 
 #if defined(__linux__)
-std::istream* GetTransparentHugePagesConfiguration() {
-  std::ifstream* ifs = new std::ifstream();
+std::istream *GetTransparentHugePagesConfiguration() {
+  std::ifstream *ifs = new std::ifstream();
 
   ifs->open("/sys/kernel/mm/transparent_hugepage/enabled");
   if (!*ifs) {
@@ -269,7 +269,7 @@ std::istream* GetTransparentHugePagesConfiguration() {
   return ifs;
 }
 
-bool IsTransparentHugePagesEnabledViaConfiguration(std::istream* configuration) {
+bool IsTransparentHugePagesEnabledViaConfiguration(std::istream *configuration) {
   std::string token;
   while (*configuration >> token) {
     if (token == "[always]" || token == "[madvise]") return true;
@@ -278,7 +278,7 @@ bool IsTransparentHugePagesEnabledViaConfiguration(std::istream* configuration)
 }
 
 bool IsTransparentHugePagesEnabled() {
-  std::istream* configuration = GetTransparentHugePagesConfiguration();
+  std::istream *configuration = GetTransparentHugePagesConfiguration();
   if (configuration == nullptr) {
     return false;
   }

From 53d148d6a39e47273fc23278eb1a8f507748174e Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:34:37 +0000
Subject: [PATCH 13/20] Revert "src: refactor: return early when we discover
 that huge tables is enabled in the configuration stream"

This reverts commit 519f21264b2430956da866d4cf20bd9f20c78ce4.
---
 src/large_pages/node_large_page.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index d809217a17d18f..75e3640579e152 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -270,11 +270,12 @@ std::istream *GetTransparentHugePagesConfiguration() {
 }
 
 bool IsTransparentHugePagesEnabledViaConfiguration(std::istream *configuration) {
+  bool enabled = false;
   std::string token;
   while (*configuration >> token) {
-    if (token == "[always]" || token == "[madvise]") return true;
+    enabled = enabled || token == "[always]" || token == "[madvise]";
   }
-  return false;
+  return enabled;
 }
 
 bool IsTransparentHugePagesEnabled() {

From 759b8095774af2b673562afdb9d7e1293c79fd89 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:34:50 +0000
Subject: [PATCH 14/20] Revert "src: extract
 IsTransparentHugePagesEnabledViaConfiguration function to determine huge
 tables enabled state based on the contents of a configuration stream"

This reverts commit 72dd2f3c8336d49333f252f73d20e9ac732838bc.
---
 src/large_pages/node_large_page.cc | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 75e3640579e152..789fbc6b93e1f1 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -269,21 +269,17 @@ std::istream *GetTransparentHugePagesConfiguration() {
   return ifs;
 }
 
-bool IsTransparentHugePagesEnabledViaConfiguration(std::istream *configuration) {
-  bool enabled = false;
-  std::string token;
-  while (*configuration >> token) {
-    enabled = enabled || token == "[always]" || token == "[madvise]";
-  }
-  return enabled;
-}
-
 bool IsTransparentHugePagesEnabled() {
   std::istream *configuration = GetTransparentHugePagesConfiguration();
   if (configuration == nullptr) {
     return false;
   }
-  bool enabled = IsTransparentHugePagesEnabledViaConfiguration(configuration);
+
+  bool enabled = false;
+  std::string token;
+  while (*configuration >> token) {
+    enabled = enabled || token == "[always]" || token == "[madvise]";
+  }
   delete configuration;
   return enabled;
 }

From 37bf5f96f1147aaf634ef496d6e9b70a877f3d0d Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:35:09 +0000
Subject: [PATCH 15/20] Revert "src: extract
 GetTransparentHugePagesConfiguration function to read system huge tables
 configuration on Linux-based systems"

This reverts commit a7fe1932a49685bd388917ec3e7c68325d123fb3.
---
 src/large_pages/node_large_page.cc | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 789fbc6b93e1f1..e72c55310f2db3 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -257,30 +257,24 @@ struct text_region FindNodeTextRegion() {
 }
 
 #if defined(__linux__)
-std::istream *GetTransparentHugePagesConfiguration() {
-  std::ifstream *ifs = new std::ifstream();
+bool IsTransparentHugePagesEnabled() {
+  std::ifstream ifs;
 
-  ifs->open("/sys/kernel/mm/transparent_hugepage/enabled");
-  if (!*ifs) {
+  ifs.open("/sys/kernel/mm/transparent_hugepage/enabled");
+  if (!ifs) {
     PrintWarning("could not open /sys/kernel/mm/transparent_hugepage/enabled");
-    return nullptr;
-  }
-
-  return ifs;
-}
-
-bool IsTransparentHugePagesEnabled() {
-  std::istream *configuration = GetTransparentHugePagesConfiguration();
-  if (configuration == nullptr) {
     return false;
   }
 
   bool enabled = false;
-  std::string token;
-  while (*configuration >> token) {
-    enabled = enabled || token == "[always]" || token == "[madvise]";
+  if (ifs.is_open()) {
+    std::string token;
+    while (ifs >> token) {
+      enabled = enabled || token == "[always]" || token == "[madvise]";
+    }
   }
-  delete configuration;
+  ifs.close();
+
   return enabled;
 }
 #elif defined(__FreeBSD__)

From e299a652d83ad8a859ab0f29f53050293386acf5 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:35:55 +0000
Subject: [PATCH 16/20] Revert "src: add an explicit default value for the
 'enabled' bool variable"

This reverts commit 53648a00b20d7d39042e1695aab0313e7dbf89b7.
---
 src/large_pages/node_large_page.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index e72c55310f2db3..3c984322d4fa57 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -266,7 +266,7 @@ bool IsTransparentHugePagesEnabled() {
     return false;
   }
 
-  bool enabled = false;
+  bool enabled;
   if (ifs.is_open()) {
     std::string token;
     while (ifs >> token) {

From d00fce6676cd63ef28dd0544001213c56e855d51 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:36:12 +0000
Subject: [PATCH 17/20] Revert "src: inspect kernel transparent_hugepage flag
 values without assuming their length or ordering"

This reverts commit 72082b9956c6b360cf2b27107a36ba307cf3c2b3.
---
 src/large_pages/node_large_page.cc | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 3c984322d4fa57..bb467b6902b459 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -266,16 +266,13 @@ bool IsTransparentHugePagesEnabled() {
     return false;
   }
 
-  bool enabled;
+  std::string always, madvise;
   if (ifs.is_open()) {
-    std::string token;
-    while (ifs >> token) {
-      enabled = enabled || token == "[always]" || token == "[madvise]";
-    }
+    ifs >> always >> madvise;
   }
   ifs.close();
 
-  return enabled;
+  return always == "[always]" || madvise == "[madvise]";
 }
 #elif defined(__FreeBSD__)
 bool IsSuperPagesEnabled() {

From e7f1cf0ab3e83729edb0a78b38fdecd06a58cea8 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Wed, 27 Jan 2021 14:38:35 +0000
Subject: [PATCH 18/20] src: add Linux huge memory enabled system flag file
 format reference

---
 src/large_pages/node_large_page.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index bb467b6902b459..38594d5fecf857 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -260,6 +260,8 @@ struct text_region FindNodeTextRegion() {
 bool IsTransparentHugePagesEnabled() {
   std::ifstream ifs;
 
+  // File format reference:
+  // https://github.com/torvalds/linux/blob/13391c60da3308ed9980de0168f74cce6c62ac1d/mm/huge_memory.c#L162-L177
   ifs.open("/sys/kernel/mm/transparent_hugepage/enabled");
   if (!ifs) {
     PrintWarning("could not open /sys/kernel/mm/transparent_hugepage/enabled");

From 572b34aaf1d1c52df7b4087de33b8b37b73af75c Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Thu, 28 Jan 2021 18:52:00 +0000
Subject: [PATCH 19/20] src: update documentation reference to use the source
 of truth

---
 src/large_pages/node_large_page.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 38594d5fecf857..0ce6d321bafe1c 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -261,7 +261,7 @@ bool IsTransparentHugePagesEnabled() {
   std::ifstream ifs;
 
   // File format reference:
-  // https://github.com/torvalds/linux/blob/13391c60da3308ed9980de0168f74cce6c62ac1d/mm/huge_memory.c#L162-L177
+  // https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/huge_memory.c?id=13391c60da3308ed9980de0168f74cce6c62ac1d#n162
   ifs.open("/sys/kernel/mm/transparent_hugepage/enabled");
   if (!ifs) {
     PrintWarning("could not open /sys/kernel/mm/transparent_hugepage/enabled");

From 239589b951444a8335fea81cf2434690a5c7c9c3 Mon Sep 17 00:00:00 2001
From: James Addison <jay@jp-hosting.net>
Date: Thu, 28 Jan 2021 18:52:40 +0000
Subject: [PATCH 20/20] src: nit: update documentation reference to link to the
 line that the relevant function is declared on

---
 src/large_pages/node_large_page.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/large_pages/node_large_page.cc b/src/large_pages/node_large_page.cc
index 0ce6d321bafe1c..22810ef08fb878 100644
--- a/src/large_pages/node_large_page.cc
+++ b/src/large_pages/node_large_page.cc
@@ -261,7 +261,7 @@ bool IsTransparentHugePagesEnabled() {
   std::ifstream ifs;
 
   // File format reference:
-  // https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/huge_memory.c?id=13391c60da3308ed9980de0168f74cce6c62ac1d#n162
+  // https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/huge_memory.c?id=13391c60da3308ed9980de0168f74cce6c62ac1d#n163
   ifs.open("/sys/kernel/mm/transparent_hugepage/enabled");
   if (!ifs) {
     PrintWarning("could not open /sys/kernel/mm/transparent_hugepage/enabled");