diff --git a/mesosphere/include/mesosphere/arch/arm64/KInterruptMaskGuard.hpp b/mesosphere/include/mesosphere/arch/arm64/KInterruptMaskGuard.hpp
index 06f8a9e95..716252b26 100644
--- a/mesosphere/include/mesosphere/arch/arm64/KInterruptMaskGuard.hpp
+++ b/mesosphere/include/mesosphere/arch/arm64/KInterruptMaskGuard.hpp
@@ -45,7 +45,7 @@ class KInterruptMaskGuard final {
     KInterruptMaskGuard &operator=(KInterruptMaskGuard &&) = delete;
 
     private:
-    FlagsType flags;
+    FlagsType flags = 0;
 };
 
 }
diff --git a/mesosphere/include/mesosphere/interrupts/KInterruptSpinLock.hpp b/mesosphere/include/mesosphere/interrupts/KInterruptSpinLock.hpp
index 67df6c2d2..f22e7755d 100644
--- a/mesosphere/include/mesosphere/interrupts/KInterruptSpinLock.hpp
+++ b/mesosphere/include/mesosphere/interrupts/KInterruptSpinLock.hpp
@@ -12,7 +12,7 @@ inline void IncrementThreadInterruptBottomHalfLockCount(KThread &thread);
 inline void DecrementThreadInterruptBottomHalfLockCount(KThread &thread);
 
 template<bool disableInterrupts = false>
-class KInterruptSpinLock final : public KSpinLock {
+class KInterruptSpinLock : public KSpinLock {
     public:
 
     bool try_lock()
@@ -48,7 +48,7 @@ class KInterruptSpinLock final : public KSpinLock {
 };
 
 template<>
-class KInterruptSpinLock<true> final : public KSpinLock {
+class KInterruptSpinLock<true> : public KSpinLock {
     public:
 
     bool try_lock()
@@ -80,7 +80,7 @@ class KInterruptSpinLock<true> final : public KSpinLock {
     KInterruptSpinLock &operator=(KInterruptSpinLock &&) = delete;
 
     private:
-    typename KInterruptMaskGuard::FlagsType flags;
+    typename KInterruptMaskGuard::FlagsType flags = 0;
 };
 
 }
diff --git a/mesosphere/include/mesosphere/threading/KCriticalSection.hpp b/mesosphere/include/mesosphere/threading/KCriticalSection.hpp
new file mode 100644
index 000000000..ecbbcb640
--- /dev/null
+++ b/mesosphere/include/mesosphere/threading/KCriticalSection.hpp
@@ -0,0 +1,26 @@
+#pragma once
+
+#include <mesosphere/interrupts/KInterruptSpinLock.hpp>
+
+namespace mesosphere
+{
+
+class KCriticalSection final : public KInterruptSpinLock<false> {
+    public:
+
+    bool try_lock();
+    void lock();
+    void unlock();
+
+    KCriticalSection() = default;
+    KCriticalSection(const KCriticalSection &) = delete;
+    KCriticalSection(KCriticalSection &&) = delete;
+    KCriticalSection &operator=(const KCriticalSection &) = delete;
+    KCriticalSection &operator=(KCriticalSection &&) = delete;
+
+    private:
+    KThread *lockingThread = nullptr;
+    ulong lockCount = 0;
+};
+
+}
diff --git a/mesosphere/include/mesosphere/threading/KScheduler.hpp b/mesosphere/include/mesosphere/threading/KScheduler.hpp
index 7c4180f60..1844c8880 100644
--- a/mesosphere/include/mesosphere/threading/KScheduler.hpp
+++ b/mesosphere/include/mesosphere/threading/KScheduler.hpp
@@ -4,14 +4,12 @@
 #include <mutex>
 #include <mesosphere/core/util.hpp>
 #include <mesosphere/threading/KMultiLevelQueue.hpp>
+#include <mesosphere/threading/KCriticalSection.hpp>
 #include <mesosphere/threading/KThread.hpp>
 
 namespace mesosphere
 {
 
-//TODO
-struct KCriticalSection { void lock() {} void unlock() {} bool try_lock() {return true;} };
-
 class KScheduler {
     public:
     class Global {
@@ -40,6 +38,8 @@ class KScheduler {
 
             static constexpr uint minRegularPriority = 2;
         private:
+            friend class KScheduler;
+
             static void TransferThreadToCore(KThread &thread, int coreId);
             static void AskForReselectionOrMarkRedundant(KThread *currentThread, KThread *winner);
 
@@ -91,6 +91,11 @@ class KScheduler {
     static void YieldCurrentThreadAndBalanceLoad();
     static void YieldCurrentThreadAndWaitForLoadBalancing();
 
+    static void HandleCriticalSectionLeave();
+    friend void SchedulerHandleCriticalSectionLeave()
+    {
+        HandleCriticalSectionLeave();
+    }
 
     void ForceContextSwitch() {}
     void ForceContextSwitchAfterIrq() {}
@@ -99,6 +104,7 @@ class KScheduler {
 
     constexpr ulong GetIdleSelectionCount() const { return idleSelectionCount; }
     constexpr bool IsActive() const { return /*isActive */ true; } // TODO
+
     private:
     bool hasContextSwitchStartedAfterIrq;
     bool isActive;
@@ -128,11 +134,4 @@ class KScheduler {
     }
 };
 
-// Convenience 
-
-class KScopedCriticalSection {
-    private:
-        std::scoped_lock<KCriticalSection> lk{KScheduler::GetCriticalSection()};
-};
-
 }
diff --git a/mesosphere/include/mesosphere/threading/KScopedCriticalSection.hpp b/mesosphere/include/mesosphere/threading/KScopedCriticalSection.hpp
new file mode 100644
index 000000000..4d9df0df6
--- /dev/null
+++ b/mesosphere/include/mesosphere/threading/KScopedCriticalSection.hpp
@@ -0,0 +1,13 @@
+#pragma once
+
+#include <mesosphere/threading/KScheduler.hpp>
+
+namespace mesosphere
+{
+
+class KScopedCriticalSection final {
+    private:
+    std::scoped_lock<KCriticalSection> lk{KScheduler::GetCriticalSection()};
+};
+
+}
diff --git a/mesosphere/source/core/KSynchronizationObject.cpp b/mesosphere/source/core/KSynchronizationObject.cpp
index c58cb992e..feea92987 100644
--- a/mesosphere/source/core/KSynchronizationObject.cpp
+++ b/mesosphere/source/core/KSynchronizationObject.cpp
@@ -1,6 +1,6 @@
 #include <mesosphere/core/KSynchronizationObject.hpp>
 #include <mesosphere/core/Result.hpp>
-#include <mesosphere/threading/KScheduler.hpp>
+#include <mesosphere/threading/KScopedCriticalSection.hpp>
 #include <mesosphere/threading/KThread.hpp>
 
 #include <mutex>
diff --git a/mesosphere/source/processes/KReadableEvent.cpp b/mesosphere/source/processes/KReadableEvent.cpp
index 0c86ea3fb..bce2834e0 100644
--- a/mesosphere/source/processes/KReadableEvent.cpp
+++ b/mesosphere/source/processes/KReadableEvent.cpp
@@ -1,7 +1,7 @@
 #include <mesosphere/processes/KWritableEvent.hpp>
 #include <mesosphere/processes/KReadableEvent.hpp>
 #include <mesosphere/processes/KEvent.hpp>
-#include <mesosphere/threading/KScheduler.hpp>
+#include <mesosphere/threading/KScopedCriticalSection.hpp>
 
 namespace mesosphere
 {
@@ -18,12 +18,12 @@ KReadableEvent::~KReadableEvent()
 Result KReadableEvent::Signal()
 {
     KScopedCriticalSection criticalSection{};
-    
+
     if (!this->isSignaled) {
         this->isSignaled = true;
         NotifyWaiters();
     }
-    
+
     return ResultSuccess();
 }
 
diff --git a/mesosphere/source/threading/KConditionVariable.cpp b/mesosphere/source/threading/KConditionVariable.cpp
index bab058971..ea2787047 100644
--- a/mesosphere/source/threading/KConditionVariable.cpp
+++ b/mesosphere/source/threading/KConditionVariable.cpp
@@ -1,5 +1,5 @@
 #include <mesosphere/threading/KConditionVariable.hpp>
-#include <mesosphere/threading/KScheduler.hpp>
+#include <mesosphere/threading/KScopedCriticalSection.hpp>
 #include <mesosphere/core/KCoreContext.hpp>
 
 namespace mesosphere
diff --git a/mesosphere/source/threading/KCriticalSection.cpp b/mesosphere/source/threading/KCriticalSection.cpp
new file mode 100644
index 000000000..fd0568767
--- /dev/null
+++ b/mesosphere/source/threading/KCriticalSection.cpp
@@ -0,0 +1,45 @@
+#include <mesosphere/threading/KCriticalSection.hpp>
+#include <mesosphere/threading/KScheduler.hpp>
+#include <mesosphere/core/KCoreContext.hpp>
+
+namespace mesosphere
+{
+
+bool KCriticalSection::try_lock()
+{
+    KThread *curThread = KCoreContext::GetCurrentInstance().GetCurrentThread();
+    if (curThread == lockingThread) {
+        ++lockCount;
+        return true;
+    } else if (KInterruptSpinLock<false>::try_lock()) {
+        lockingThread = curThread;
+        lockCount = 1;
+        return true;
+    } else {
+        return false;
+    }
+}
+
+void KCriticalSection::lock()
+{
+    KThread *curThread = KCoreContext::GetCurrentInstance().GetCurrentThread();
+    if (curThread == lockingThread) {
+        ++lockCount;
+    } else {
+        KInterruptSpinLock<false>::lock();
+        lockingThread = curThread;
+        lockCount = 1;
+    }
+}
+
+void KCriticalSection::unlock()
+{
+    if (--lockCount == 0) {
+        lockingThread = nullptr;
+        KScheduler::HandleCriticalSectionLeave();
+    } else {
+        KInterruptSpinLock<false>::unlock();
+    }
+}
+
+}
diff --git a/mesosphere/source/threading/KMutex.cpp b/mesosphere/source/threading/KMutex.cpp
index e2c036e33..7b7aaa591 100644
--- a/mesosphere/source/threading/KMutex.cpp
+++ b/mesosphere/source/threading/KMutex.cpp
@@ -1,6 +1,6 @@
 #include <mesosphere/threading/KMutex.hpp>
 #include <mesosphere/threading/KThread.hpp>
-#include <mesosphere/threading/KScheduler.hpp>
+#include <mesosphere/threading/KScopedCriticalSection.hpp>
 
 namespace mesosphere
 {
diff --git a/mesosphere/source/threading/KScheduler.cpp b/mesosphere/source/threading/KScheduler.cpp
index 7a91806c8..db22c91b5 100644
--- a/mesosphere/source/threading/KScheduler.cpp
+++ b/mesosphere/source/threading/KScheduler.cpp
@@ -341,4 +341,15 @@ void KScheduler::YieldCurrentThreadAndWaitForLoadBalancing()
     cctx.GetScheduler()->DoYieldOperation(Global::YieldThreadAndWaitForLoadBalancing, *cctx.GetCurrentThread());
 }
 
+void KScheduler::HandleCriticalSectionLeave()
+{
+    if (KScheduler::Global::reselectionRequired) {
+        KScheduler::Global::SelectThreads();
+    }
+
+    std::atomic_thread_fence(std::memory_order_seq_cst);
+
+    // TODO: check which cores needs ctx switches, sent interrupts and/or ctx switch ourselves
+}
+
 }
diff --git a/mesosphere/source/threading/KThread.cpp b/mesosphere/source/threading/KThread.cpp
index 856d90ae9..cd0a2da42 100644
--- a/mesosphere/source/threading/KThread.cpp
+++ b/mesosphere/source/threading/KThread.cpp
@@ -3,7 +3,7 @@
 #include <algorithm>
 
 #include <mesosphere/threading/KThread.hpp>
-#include <mesosphere/threading/KScheduler.hpp>
+#include <mesosphere/threading/KScopedCriticalSection.hpp>
 
 namespace mesosphere
 {