diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
index 64aeee1..0329a4d 100644
--- a/Documentation/admin-guide/sysctl/vm.rst
+++ b/Documentation/admin-guide/sysctl/vm.rst
@@ -128,6 +128,9 @@
 This should be used on systems where stalls for minor page faults are an
 acceptable trade for large contiguous free memory.  Set to 0 to prevent
 compaction from moving pages that are unevictable.  Default value is 1.
+On CONFIG_PREEMPT_RT the default value is 0 in order to avoid a page fault, due
+to compaction, which would block the task from becomming active until the fault
+is resolved.
 
 
 dirty_background_bytes
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index d08bd51..8221219 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -212,6 +212,11 @@ static int proc_do_cad_pid(struct ctl_table *table, int write,
 		  void __user *buffer, size_t *lenp, loff_t *ppos);
 static int proc_taint(struct ctl_table *table, int write,
 			       void __user *buffer, size_t *lenp, loff_t *ppos);
+#ifdef CONFIG_COMPACTION
+static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table,
+					       int write, void __user *buffer,
+					       size_t *lenp, loff_t *ppos);
+#endif
 #endif
 
 #ifdef CONFIG_PRINTK
@@ -1488,17 +1493,16 @@ static struct ctl_table vm_table[] = {
 		.extra1		= &min_extfrag_threshold,
 		.extra2		= &max_extfrag_threshold,
 	},
-#ifndef CONFIG_PREEMPT_RT
 	{
 		.procname	= "compact_unevictable_allowed",
 		.data		= &sysctl_compact_unevictable_allowed,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax_warn_RT_change,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
-#endif
+
 #endif /* CONFIG_COMPACTION */
 	{
 		.procname	= "min_free_kbytes",
@@ -2582,6 +2586,28 @@ int proc_dointvec(struct ctl_table *table, int write,
 	return do_proc_dointvec(table, write, buffer, lenp, ppos, NULL, NULL);
 }
 
+#ifdef CONFIG_COMPACTION
+static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table,
+					       int write, void __user *buffer,
+					       size_t *lenp, loff_t *ppos)
+{
+	int ret, old;
+
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT) || !write)
+		return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+
+	old = *(int *)table->data;
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret)
+		return ret;
+	if (old != *(int *)table->data)
+		pr_warn_once("sysctl attribute %s changed by %s[%d]\n",
+			     table->procname, current->comm,
+			     task_pid_nr(current));
+	return ret;
+}
+#endif
+
 /**
  * proc_douintvec - read a vector of unsigned integers
  * @table: the sysctl table
diff --git a/mm/compaction.c b/mm/compaction.c
index 83cc3d1..31e6e10 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1591,7 +1591,7 @@ typedef enum {
  * compactable pages.
  */
 #ifdef CONFIG_PREEMPT_RT
-#define sysctl_compact_unevictable_allowed 0
+int sysctl_compact_unevictable_allowed __read_mostly = 0;
 #else
 int sysctl_compact_unevictable_allowed __read_mostly = 1;
 #endif