Index: sys/arm/include/proc.h
===================================================================
--- sys/arm/include/proc.h
+++ sys/arm/include/proc.h
@@ -80,4 +80,17 @@
 	register_t args[MAXARGS];
 } __aligned(8);
 
+#ifdef _KERNEL
+#include <machine/pcb.h>
+
+/* Get the current kernel thread stack usage. */
+#define	GET_STACK_USAGE(total, used) do {				\
+	struct thread *td = curthread;					\
+	(total) = td->td_kstack_pages * PAGE_SIZE - sizeof(struct pcb);	\
+	(used) = (char *)td->td_kstack +				\
+	    td->td_kstack_pages * PAGE_SIZE -				\
+	    (char *)&td;						\
+} while (0)
+
+#endif  /* _KERNEL */
 #endif /* !_MACHINE_PROC_H_ */
Index: sys/geom/geom_io.c
===================================================================
--- sys/geom/geom_io.c
+++ sys/geom/geom_io.c
@@ -559,7 +559,6 @@
 	atomic_add_int(&cp->nstart, 1);
 #endif
 
-#ifdef GET_STACK_USAGE
 	direct = (cp->flags & G_CF_DIRECT_SEND) != 0 &&
 	    (pp->flags & G_PF_DIRECT_RECEIVE) != 0 &&
 	    !g_is_geom_thread(curthread) &&
@@ -573,9 +572,6 @@
 		if (su * 2 > st)
 			direct = 0;
 	}
-#else
-	direct = 0;
-#endif
 
 	if (direct) {
 		error = g_io_check(bp);
@@ -655,7 +651,6 @@
 	bp->bio_bcount = bp->bio_length;
 	bp->bio_resid = bp->bio_bcount - bp->bio_completed;
 
-#ifdef GET_STACK_USAGE
 	direct = (pp->flags & G_PF_DIRECT_SEND) &&
 		 (cp->flags & G_CF_DIRECT_RECEIVE) &&
 		 !g_is_geom_thread(curthread);
@@ -666,9 +661,6 @@
 		if (su * 2 > st)
 			direct = 0;
 	}
-#else
-	direct = 0;
-#endif
 
 	/*
 	 * The statistics collection is lockless, as such, but we
Index: sys/mips/include/proc.h
===================================================================
--- sys/mips/include/proc.h
+++ sys/mips/include/proc.h
@@ -96,4 +96,17 @@
 #define	KINFO_PROC_SIZE 816
 #endif
 
+#ifdef _KERNEL
+#include <machine/pcb.h>
+
+/* Get the current kernel thread stack usage. */
+#define	GET_STACK_USAGE(total, used) do {				\
+	struct thread *td = curthread;					\
+	(total) = td->td_kstack_pages * PAGE_SIZE - sizeof(struct pcb);	\
+	(used) = (char *)td->td_kstack +				\
+	    td->td_kstack_pages * PAGE_SIZE -				\
+	    (char *)&td;						\
+} while (0)
+
+#endif  /* _KERNEL */
 #endif	/* !_MACHINE_PROC_H_ */
Index: sys/netgraph/ng_base.c
===================================================================
--- sys/netgraph/ng_base.c
+++ sys/netgraph/ng_base.c
@@ -2281,7 +2281,7 @@
 		queue = 1;
 	} else {
 		queue = 0;
-#ifdef GET_STACK_USAGE
+
 		/*
 		 * Most of netgraph nodes have small stack consumption and
 		 * for them 25% of free stack space is more than enough.
@@ -2296,7 +2296,6 @@
 		    ((node->nd_flags & NGF_HI_STACK) || (hook &&
 		    (hook->hk_flags & HK_HI_STACK)))))
 			queue = 1;
-#endif
 	}
 
 	if (queue) {
Index: sys/riscv/include/proc.h
===================================================================
--- sys/riscv/include/proc.h
+++ sys/riscv/include/proc.h
@@ -53,4 +53,17 @@
 	register_t args[MAXARGS];
 };
 
+#ifdef _KERNEL
+#include <machine/pcb.h>
+
+/* Get the current kernel thread stack usage. */
+#define	GET_STACK_USAGE(total, used) do {				\
+	struct thread *td = curthread;					\
+	(total) = td->td_kstack_pages * PAGE_SIZE - sizeof(struct pcb);	\
+	(used) = (char *)td->td_kstack +				\
+	    td->td_kstack_pages * PAGE_SIZE -				\
+	    (char *)&td;						\
+} while (0)
+
+#endif  /* _KERNEL */
 #endif /* !_MACHINE_PROC_H_ */