Index: head/sys/kern/subr_pcpu.c
===================================================================
--- head/sys/kern/subr_pcpu.c
+++ head/sys/kern/subr_pcpu.c
@@ -95,6 +95,7 @@
 	cpu_pcpu_init(pcpu, cpuid, size);
 	pcpu->pc_rm_queue.rmq_next = &pcpu->pc_rm_queue;
 	pcpu->pc_rm_queue.rmq_prev = &pcpu->pc_rm_queue;
+	pcpu->pc_zpcpu_offset = zpcpu_offset_cpu(cpuid);
 }
 
 void
Index: head/sys/riscv/include/pcpu.h
===================================================================
--- head/sys/riscv/include/pcpu.h
+++ head/sys/riscv/include/pcpu.h
@@ -48,7 +48,7 @@
 	struct pmap *pc_curpmap;	/* Currently active pmap */	\
 	uint32_t pc_pending_ipis;	/* IPIs pending to this CPU */	\
 	uint32_t pc_hart;		/* Hart ID */			\
-	char __pad[57]
+	char __pad[49]
 
 #ifdef _KERNEL
 
Index: head/sys/sys/pcpu.h
===================================================================
--- head/sys/sys/pcpu.h
+++ head/sys/sys/pcpu.h
@@ -194,6 +194,7 @@
 	struct rm_queue	pc_rm_queue;		/* rmlock list of trackers */
 	uintptr_t	pc_dynamic;		/* Dynamic per-cpu data area */
 	uint64_t	pc_early_dummy_counter;	/* Startup time counter(9) */
+	uintptr_t	pc_zpcpu_offset;	/* Offset into zpcpu allocs */
 
 	/*
 	 * Keep MD fields last, so that CPU-specific variations on a
@@ -227,14 +228,28 @@
 #endif
 #define	curproc		(curthread->td_proc)
 
+#ifndef zpcpu_offset_cpu
+#define zpcpu_offset_cpu(cpu)	(UMA_PCPU_ALLOC_SIZE * cpu)
+#endif
+#ifndef zpcpu_offset
+#define zpcpu_offset()		(PCPU_GET(zpcpu_offset))
+#endif
+
+#ifndef zpcpu_base_to_offset
+#define zpcpu_base_to_offset(base) (base)
+#endif
+#ifndef zpcpu_offset_to_base
+#define zpcpu_offset_to_base(base) (base)
+#endif
+
 /* Accessor to elements allocated via UMA_ZONE_PCPU zone. */
 #define zpcpu_get(base) ({								\
-	__typeof(base) _ptr = (void *)((char *)(base) + UMA_PCPU_ALLOC_SIZE * curcpu);	\
+	__typeof(base) _ptr = (void *)((char *)(base) + zpcpu_offset());		\
 	_ptr;										\
 })
 
 #define zpcpu_get_cpu(base, cpu) ({							\
-	__typeof(base) _ptr = (void *)((char *)(base) +	UMA_PCPU_ALLOC_SIZE * cpu);	\
+	__typeof(base) _ptr = (void *)((char *)(base) +	zpcpu_offset_cpu(cpu));		\
 	_ptr;										\
 })
 
Index: head/sys/vm/uma_core.c
===================================================================
--- head/sys/vm/uma_core.c
+++ head/sys/vm/uma_core.c
@@ -2944,34 +2944,39 @@
 void *
 uma_zalloc_pcpu_arg(uma_zone_t zone, void *udata, int flags)
 {
-	void *item;
+	void *item, *pcpu_item;
 #ifdef SMP
 	int i;
 
 	MPASS(zone->uz_flags & UMA_ZONE_PCPU);
 #endif
 	item = uma_zalloc_arg(zone, udata, flags & ~M_ZERO);
-	if (item != NULL && (flags & M_ZERO)) {
+	if (item == NULL)
+		return (NULL);
+	pcpu_item = zpcpu_base_to_offset(item);
+	if (flags & M_ZERO) {
 #ifdef SMP
 		for (i = 0; i <= mp_maxid; i++)
-			bzero(zpcpu_get_cpu(item, i), zone->uz_size);
+			bzero(zpcpu_get_cpu(pcpu_item, i), zone->uz_size);
 #else
 		bzero(item, zone->uz_size);
 #endif
 	}
-	return (item);
+	return (pcpu_item);
 }
 
 /*
  * A stub while both regular and pcpu cases are identical.
  */
 void
-uma_zfree_pcpu_arg(uma_zone_t zone, void *item, void *udata)
+uma_zfree_pcpu_arg(uma_zone_t zone, void *pcpu_item, void *udata)
 {
+	void *item;
 
 #ifdef SMP
 	MPASS(zone->uz_flags & UMA_ZONE_PCPU);
 #endif
+	item = zpcpu_offset_to_base(pcpu_item);
 	uma_zfree_arg(zone, item, udata);
 }