Index: sys/kern/subr_vmem.c
===================================================================
--- sys/kern/subr_vmem.c
+++ sys/kern/subr_vmem.c
@@ -507,6 +507,9 @@
 
 /*
  * Import from the arena into the quantum cache in UMA.
+ *
+ * We use VMEM_ADDR_QCACHE_MIN instead of 0: UMA uses 0 to indicate an
+ * allocation failure, so it can't be used to cache a resource with value 0.
  */
 static int
 qc_import(void *arg, void **store, int cnt, int domain, int flags)
@@ -520,7 +523,7 @@
 		flags |= M_BESTFIT;
 	for (i = 0; i < cnt; i++) {
 		if (vmem_xalloc(qc->qc_vmem, qc->qc_size, 0, 0, 0,
-		    VMEM_ADDR_MIN, VMEM_ADDR_MAX, flags, &addr) != 0)
+		    VMEM_ADDR_QCACHE_MIN, VMEM_ADDR_MAX, flags, &addr) != 0)
 			break;
 		store[i] = (void *)addr;
 		/* Only guarantee one allocation. */
Index: sys/sys/vmem.h
===================================================================
--- sys/sys/vmem.h
+++ sys/sys/vmem.h
@@ -41,8 +41,9 @@
 typedef uintptr_t	vmem_addr_t;
 typedef size_t		vmem_size_t;
 
-#define	VMEM_ADDR_MIN	0
-#define	VMEM_ADDR_MAX	(~(vmem_addr_t)0)
+#define	VMEM_ADDR_MIN		0
+#define	VMEM_ADDR_QCACHE_MIN	1
+#define	VMEM_ADDR_MAX		(~(vmem_addr_t)0)
 
 typedef int (vmem_import_t)(void *, vmem_size_t, int, vmem_addr_t *);
 typedef void (vmem_release_t)(void *, vmem_addr_t, vmem_size_t);