diff --git a/init/init.c b/init/init.c
index 2da856f..c075a4d 100644
--- a/init/init.c
+++ b/init/init.c
@@ -14,9 +14,14 @@ int mutex_rid;
 void mythread (void) {
   for (int j = 0; j < 10; j++) {
     proc_mutex_lock (mutex_rid, RV_PRIVATE);
+
     for (size_t i = 0; i < 3; i++)
       proc_test ('b');
+
     proc_mutex_unlock (mutex_rid, RV_PRIVATE);
+
+    for (volatile int i = 0; i < 200 * 1000 * 1000; i++)
+      ;
   }
 
   proc_quit ();
@@ -39,9 +44,14 @@ void app_main (void) {
 
   for (int j = 0; j < 10; j++) {
     proc_mutex_lock (mutex_rid, RV_PRIVATE);
+
     for (size_t i = 0; i < 3; i++)
       proc_test ('a');
+
     proc_mutex_unlock (mutex_rid, RV_PRIVATE);
+
+    for (volatile int i = 0; i < 400 * 1000 * 1000; i++)
+      ;
   }
 
   for (;;)
diff --git a/kernel/amd64/apic.c b/kernel/amd64/apic.c
index 6346439..8abd8df 100644
--- a/kernel/amd64/apic.c
+++ b/kernel/amd64/apic.c
@@ -77,7 +77,7 @@ static void amd64_ioapic_write (struct ioapic* ioapic, uint32_t reg, uint32_t va
 }
 
 /* Find an IOAPIC corresposting to provided IRQ */
-static struct ioapic* amd64_ioapic_find (uint8_t irq) {
+static struct ioapic* amd64_ioapic_find (uint32_t irq) {
   struct ioapic* ioapic = NULL;
 
   for (size_t i = 0; i < ioapic_entries; i++) {
@@ -103,7 +103,7 @@ static struct ioapic* amd64_ioapic_find (uint8_t irq) {
  * flags - IOAPIC redirection flags.
  * lapic_id - Local APIC that will receive the interrupt.
  */
-void amd64_ioapic_route_irq (uint8_t vec, uint8_t irq, uint64_t flags, uint64_t lapic_id) {
+void amd64_ioapic_route_irq (uint32_t vec, uint32_t irq, uint64_t flags, uint64_t lapic_id) {
   struct ioapic* ioapic = NULL;
   struct acpi_madt_interrupt_source_override* override;
   bool found_override = false;
@@ -119,13 +119,13 @@ void amd64_ioapic_route_irq (uint8_t vec, uint8_t irq, uint64_t flags, uint64_t
   uint64_t calc_flags = (lapic_id << 56) | (flags) | (vec & 0xFF);
 
   if (found_override) {
-    uint8_t polarity = ((override->flags & 0x03) == 0x03) ? 1 : 0;
-    uint8_t mode = (((override->flags >> 2) & 0x03) == 0x03) ? 1 : 0;
+    uint32_t polarity = ((override->flags & 0x03) == 0x03) ? 1 : 0;
+    uint32_t mode = (((override->flags >> 2) & 0x03) == 0x03) ? 1 : 0;
     calc_flags |= (uint64_t)mode << 15;
     calc_flags |= (uint64_t)polarity << 13;
   }
 
-  uint8_t gsi = found_override ? override->gsi : irq;
+  uint32_t gsi = found_override ? override->gsi : irq;
 
   ioapic = amd64_ioapic_find (gsi);
 
@@ -263,7 +263,7 @@ void amd64_lapic_init (uint32_t us) {
  * lapic_id - Target Local APIC
  * vec - Interrupt vector/IDT stub, which will be invoked by the IPI.
  */
-void amd64_lapic_ipi (uint8_t lapic_id, uint8_t vec) {
+void amd64_lapic_ipi (uint32_t lapic_id, uint32_t vec) {
   /* wait for previous IPI to finish */
   while (amd64_lapic_read (LAPIC_ICR) & (1 << 12)) {
     __asm__ volatile ("pause");
diff --git a/kernel/amd64/apic.h b/kernel/amd64/apic.h
index 2d3f6b3..a057068 100644
--- a/kernel/amd64/apic.h
+++ b/kernel/amd64/apic.h
@@ -3,12 +3,12 @@
 
 #include <libk/std.h>
 
-void amd64_ioapic_route_irq (uint8_t vec, uint8_t irq, uint64_t flags, uint64_t lapic_id);
+void amd64_ioapic_route_irq (uint32_t vec, uint32_t irq, uint64_t flags, uint64_t lapic_id);
 void amd64_ioapic_init (void);
 
 uint32_t amd64_lapic_id (void);
 void amd64_lapic_eoi (void);
-void amd64_lapic_ipi (uint8_t lapic_id, uint8_t vec);
+void amd64_lapic_ipi (uint32_t lapic_id, uint32_t vec);
 void amd64_lapic_init (uint32_t us);
 
 #endif // _KERNEL_AMD64_APIC_H
diff --git a/kernel/amd64/intr.c b/kernel/amd64/intr.c
index 6fbe602..f00f19b 100644
--- a/kernel/amd64/intr.c
+++ b/kernel/amd64/intr.c
@@ -216,12 +216,12 @@ void irq_save (spin_lock_ctx_t* ctx) { *ctx = amd64_irq_save_flags (); }
 void irq_restore (spin_lock_ctx_t* ctx) { amd64_irq_restore_flags (*ctx); }
 
 /* Map custom IRQ mappings to legacy IRQs */
-uint8_t amd64_resolve_irq (uint8_t irq) {
-  static const uint8_t mappings[] = {
+uint32_t amd64_resolve_irq (uint32_t irq) {
+  static const uint32_t mappings[] = {
       [SCHED_PREEMPT_TIMER] = 0,
-      [TLB_SHOOTDOWN] = 1,
-      [CPU_REQUEST_SCHED] = 2,
-      [CPU_SPURIOUS] = 3,
+      [TLB_SHOOTDOWN] = 6,
+      [CPU_REQUEST_SCHED] = 3,
+      [CPU_SPURIOUS] = 5,
   };
 
   return mappings[irq];
diff --git a/kernel/amd64/intr.h b/kernel/amd64/intr.h
index cb067bf..910b7e7 100644
--- a/kernel/amd64/intr.h
+++ b/kernel/amd64/intr.h
@@ -32,7 +32,7 @@ struct saved_regs {
 } PACKED;
 
 void amd64_load_idt (void);
-uint8_t amd64_resolve_irq (uint8_t irq);
+uint32_t amd64_resolve_irq (uint32_t irq);
 void amd64_intr_init (void);
 
 #endif // _KERNEL_AMD64_INTR_H
diff --git a/kernel/irq/irq.c b/kernel/irq/irq.c
index bb459b8..e3edb18 100644
--- a/kernel/irq/irq.c
+++ b/kernel/irq/irq.c
@@ -3,6 +3,7 @@
 #include <libk/std.h>
 #include <mm/liballoc.h>
 #include <sync/rw_spin_lock.h>
+#include <sys/debug.h>
 
 #if defined(__x86_64__)
 #include <amd64/apic.h>
diff --git a/kernel/proc/mutex.c b/kernel/proc/mutex.c
index 313d878..3cf535d 100644
--- a/kernel/proc/mutex.c
+++ b/kernel/proc/mutex.c
@@ -51,26 +51,27 @@ bool proc_mutex_unlock (struct proc* proc, struct proc_mutex* mutex) {
 
   spin_lock (&mutex->suspension_q.lock, &ctxsq);
 
-  struct proc* resumed_proc;
+  struct proc* resumed_proc = NULL;
   struct rb_node_link* node;
   rbtree_first (&mutex->suspension_q.proc_tree, node);
 
   if (node) {
     resumed_proc = rbtree_entry (node, struct proc, suspension_link);
     mutex->owner = resumed_proc;
+    mutex->locked = true;
 
     spin_unlock (&mutex->suspension_q.lock, &ctxsq);
     spin_unlock (&mutex->resource->lock, &ctxmt);
+
     proc_resume (resumed_proc);
 
     return true;
   }
 
-  spin_unlock (&mutex->suspension_q.lock, &ctxsq);
-
   mutex->locked = false;
   mutex->owner = NULL;
 
+  spin_unlock (&mutex->suspension_q.lock, &ctxsq);
   spin_unlock (&mutex->resource->lock, &ctxmt);
 
   return true;
diff --git a/kernel/proc/proc.c b/kernel/proc/proc.c
index 1f5a56b..67149dd 100644
--- a/kernel/proc/proc.c
+++ b/kernel/proc/proc.c
@@ -355,10 +355,7 @@ void proc_kill (struct proc* proc, void* regs) {
 
   DEBUG ("killed PID %d\n", proc->pid);
 
-  if (cpu == thiscpu)
-    proc_sched (regs);
-  else
-    cpu_request_sched (cpu);
+  cpu_request_sched (cpu);
 }
 
 void proc_suspend (struct proc* proc, struct proc_suspension_q* sq) {
@@ -408,13 +405,7 @@ void proc_resume (struct proc* proc) {
 
 static void proc_irq_sched (void* arg, void* regs) {
   (void)arg;
-
-#if defined(__x86_64__)
-  struct saved_regs* s_regs = regs;
-  /* Only schedule, when we came from usermode */
-  if ((s_regs->cs & 0x03))
-    proc_sched (regs);
-#endif
+  proc_sched (regs);
 }
 
 static void proc_kpproc_init (void) {
@@ -470,15 +461,15 @@ static void proc_kpproc_init (void) {
 }
 
 void proc_init (void) {
+#if defined(__x86_64__)
+  irq_attach (&proc_irq_sched, NULL, SCHED_PREEMPT_TIMER, IRQ_INTERRUPT_SAFE);
+  irq_attach (&proc_irq_sched, NULL, CPU_REQUEST_SCHED, IRQ_INTERRUPT_SAFE);
+#endif
+
   proc_kpproc_init ();
 
   struct proc* init = proc_spawn_rd ("init.exe");
   proc_register (init, thiscpu);
 
-#if defined(__x86_64__)
-  irq_attach (&proc_irq_sched, NULL, SCHED_PREEMPT_TIMER, IRQ_INTERRUPT_UNSAFE);
-  irq_attach (&proc_irq_sched, NULL, CPU_REQUEST_SCHED, IRQ_INTERRUPT_UNSAFE);
-#endif
-
   do_sched (init);
 }
diff --git a/kernel/syscall/syscall.c b/kernel/syscall/syscall.c
index 7759a5c..46e8172 100644
--- a/kernel/syscall/syscall.c
+++ b/kernel/syscall/syscall.c
@@ -188,8 +188,6 @@ DEFINE_SYSCALL (sys_proc_mutex_unlock) {
   if (result < 0)
     return result;
 
-  proc_sched (regs);
-
   return ST_OK;
 }