diff --git a/src/hotspot/os_cpu/linux_x86/javaThread_linux_x86.cpp b/src/hotspot/os_cpu/linux_x86/javaThread_linux_x86.cpp
index 9e129487edf9d..145b9a3f0220a 100644
--- a/src/hotspot/os_cpu/linux_x86/javaThread_linux_x86.cpp
+++ b/src/hotspot/os_cpu/linux_x86/javaThread_linux_x86.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -28,7 +28,7 @@
 
 frame JavaThread::pd_last_frame() {
   assert(has_last_Java_frame(), "must have last_Java_sp() when suspended");
-  vmassert(_anchor.last_Java_pc() != NULL, "not walkable");
+  vmassert(_anchor.last_Java_pc() != nullptr, "not walkable");
   return frame(_anchor.last_Java_sp(), _anchor.last_Java_fp(), _anchor.last_Java_pc());
 }
 
@@ -62,7 +62,7 @@ bool JavaThread::pd_get_top_frame(frame* fr_addr, void* ucontext, bool isInJava)
     intptr_t* ret_fp;
     intptr_t* ret_sp;
     address addr = os::fetch_frame_from_context(uc, &ret_sp, &ret_fp);
-    if (addr == NULL || ret_sp == NULL ) {
+    if (addr == nullptr || ret_sp == nullptr ) {
       // ucontext wasn't useful
       return false;
     }
@@ -70,8 +70,8 @@ bool JavaThread::pd_get_top_frame(frame* fr_addr, void* ucontext, bool isInJava)
     frame ret_frame(ret_sp, ret_fp, addr);
     if (!ret_frame.safe_for_sender(this)) {
 #if COMPILER2_OR_JVMCI
-      // C2 and JVMCI use ebp as a general register see if NULL fp helps
-      frame ret_frame2(ret_sp, NULL, addr);
+      // C2 and JVMCI use ebp as a general register see if null fp helps
+      frame ret_frame2(ret_sp, nullptr, addr);
       if (!ret_frame2.safe_for_sender(this)) {
         // nothing else to try if the frame isn't good
         return false;
diff --git a/src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp b/src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp
index dfa6e6fa853d1..b67e6b9a0647b 100644
--- a/src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp
+++ b/src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -126,14 +126,14 @@ address os::fetch_frame_from_context(const void* ucVoid,
   address epc;
   const ucontext_t* uc = (const ucontext_t*)ucVoid;
 
-  if (uc != NULL) {
+  if (uc != nullptr) {
     epc = os::Posix::ucontext_get_pc(uc);
     if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
     if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
   } else {
-    epc = NULL;
-    if (ret_sp) *ret_sp = (intptr_t *)NULL;
-    if (ret_fp) *ret_fp = (intptr_t *)NULL;
+    epc = nullptr;
+    if (ret_sp) *ret_sp = (intptr_t *)nullptr;
+    if (ret_fp) *ret_fp = (intptr_t *)nullptr;
   }
 
   return epc;
@@ -209,20 +209,20 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
 
   /*
   NOTE: does not seem to work on linux.
-  if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
+  if (info == nullptr || info->si_code <= 0 || info->si_code == SI_NOINFO) {
     // can't decode this kind of signal
-    info = NULL;
+    info = nullptr;
   } else {
     assert(sig == info->si_signo, "bad siginfo");
   }
 */
   // decide if this trap can be handled by a stub
-  address stub = NULL;
+  address stub = nullptr;
 
-  address pc          = NULL;
+  address pc          = nullptr;
 
   //%note os_trap_1
-  if (info != NULL && uc != NULL && thread != NULL) {
+  if (info != nullptr && uc != nullptr && thread != nullptr) {
     pc = (address) os::Posix::ucontext_get_pc(uc);
 
     if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
@@ -260,9 +260,9 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
         // here if the underlying file has been truncated.
         // Do not crash the VM in such a case.
         CodeBlob* cb = CodeCache::find_blob(pc);
-        CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
+        CompiledMethod* nm = (cb != nullptr) ? cb->as_compiled_method_or_null() : nullptr;
         bool is_unsafe_arraycopy = thread->doing_unsafe_access() && UnsafeCopyMemory::contains_pc(pc);
-        if ((nm != NULL && nm->has_unsafe_access()) || is_unsafe_arraycopy) {
+        if ((nm != nullptr && nm->has_unsafe_access()) || is_unsafe_arraycopy) {
           address next_pc = Assembler::locate_next_instruction(pc);
           if (is_unsafe_arraycopy) {
             next_pc = UnsafeCopyMemory::page_error_continue_pc(pc);
@@ -346,7 +346,7 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
   // the si_code for this condition may change in the future.
   // Furthermore, a false-positive should be harmless.
   if (UnguardOnExecutionViolation > 0 &&
-      stub == NULL &&
+      stub == nullptr &&
       (sig == SIGSEGV || sig == SIGBUS) &&
       uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
     int page_size = os::vm_page_size();
@@ -409,9 +409,9 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
   }
 #endif // !AMD64
 
-  if (stub != NULL) {
+  if (stub != nullptr) {
     // save all thread context in case we need to restore it
-    if (thread != NULL) thread->set_saved_exception_pc(pc);
+    if (thread != nullptr) thread->set_saved_exception_pc(pc);
 
     os::Posix::ucontext_set_pc(uc, stub);
     return true;
@@ -466,9 +466,9 @@ juint os::cpu_microcode_revision() {
     size_t len = sizeof(data);
     while (!feof(fp)) {
       if (fgets(data, len, fp)) {
-        if (strstr(data, "microcode") != NULL) {
+        if (strstr(data, "microcode") != nullptr) {
           char* rev = strchr(data, ':');
-          if (rev != NULL) sscanf(rev + 1, "%x", &result);
+          if (rev != nullptr) sscanf(rev + 1, "%x", &result);
           break;
         }
       }
@@ -507,7 +507,7 @@ size_t os::Posix::default_stack_size(os::ThreadType thr_type) {
 // helper functions for fatal error handler
 
 void os::print_context(outputStream *st, const void *context) {
-  if (context == NULL) return;
+  if (context == nullptr) return;
 
   const ucontext_t *uc = (const ucontext_t*)context;
 
@@ -559,7 +559,7 @@ void os::print_context(outputStream *st, const void *context) {
 }
 
 void os::print_tos_pc(outputStream *st, const void *context) {
-  if (context == NULL) return;
+  if (context == nullptr) return;
 
   const ucontext_t* uc = (const ucontext_t*)context;
 
@@ -576,7 +576,7 @@ void os::print_tos_pc(outputStream *st, const void *context) {
 }
 
 void os::print_register_info(outputStream *st, const void *context) {
-  if (context == NULL) return;
+  if (context == nullptr) return;
 
   const ucontext_t *uc = (const ucontext_t*)context;