Index: head/sys/arm/arm/busdma_machdep-v6.c
===================================================================
--- head/sys/arm/arm/busdma_machdep-v6.c
+++ head/sys/arm/arm/busdma_machdep-v6.c
@@ -117,8 +117,8 @@
 
 struct sync_list {
 	vm_offset_t	vaddr;		/* kva of client data */
+	bus_addr_t	paddr;		/* physical address */
 	vm_page_t	pages;		/* starting page of client data */
-	vm_offset_t	dataoffs;	/* page offset of client data */
 	bus_size_t	datacount;	/* client data count */
 };
 
@@ -1076,17 +1076,19 @@
 			    sgsize);
 		} else {
 			if (map->sync_count > 0)
-				sl_end = VM_PAGE_TO_PHYS(sl->pages) +
-				    sl->dataoffs + sl->datacount;
+				sl_end = sl->paddr + sl->datacount;
 
 			if (map->sync_count == 0 || curaddr != sl_end) {
 				if (++map->sync_count > dmat->nsegments)
 					break;
 				sl++;
 				sl->vaddr = 0;
+				sl->paddr = curaddr;
 				sl->datacount = sgsize;
 				sl->pages = PHYS_TO_VM_PAGE(curaddr);
-				sl->dataoffs = curaddr & PAGE_MASK;
+				KASSERT(sl->pages != NULL,
+				    ("%s: page at PA:0x%08lx is not in "
+				    "vm_page_array", __func__, curaddr));
 			} else
 				sl->datacount += sgsize;
 		}
@@ -1188,8 +1190,7 @@
 			    sgsize);
 		} else {
 			if (map->sync_count > 0) {
-				sl_pend = VM_PAGE_TO_PHYS(sl->pages) +
-				    sl->dataoffs + sl->datacount;
+				sl_pend = sl->paddr + sl->datacount;
 				sl_vend = sl->vaddr + sl->datacount;
 			}
 
@@ -1201,9 +1202,17 @@
 					goto cleanup;
 				sl++;
 				sl->vaddr = kvaddr;
+				sl->paddr = curaddr;
+				if (kvaddr != 0) {
+					sl->pages = NULL;
+				} else {
+					sl->pages = PHYS_TO_VM_PAGE(curaddr);
+					KASSERT(sl->pages != NULL,
+					    ("%s: page at PA:0x%08lx is not "
+					    "in vm_page_array", __func__,
+					    curaddr));
+				}
 				sl->datacount = sgsize;
-				sl->pages = PHYS_TO_VM_PAGE(curaddr);
-				sl->dataoffs = curaddr & PAGE_MASK;
 			} else
 				sl->datacount += sgsize;
 		}
@@ -1299,10 +1308,10 @@
 	vm_offset_t va, tempva;
 	bus_size_t size;
 
-	offset = sl->dataoffs;
+	offset = sl->paddr & PAGE_MASK;
 	m = sl->pages;
 	size = sl->datacount;
-	pa = VM_PAGE_TO_PHYS(m) | offset;
+	pa = sl->paddr;
 
 	for ( ; size != 0; size -= len, pa += len, offset = 0, ++m) {
 		tempva = 0;
@@ -1310,13 +1319,13 @@
 			len = min(PAGE_SIZE - offset, size);
 			tempva = pmap_quick_enter_page(m);
 			va = tempva | offset;
+			KASSERT(pa == (VM_PAGE_TO_PHYS(m) | offset),
+			    ("unexpected vm_page_t phys: 0x%08x != 0x%08x",
+			    VM_PAGE_TO_PHYS(m) | offset, pa));
 		} else {
 			len = sl->datacount;
 			va = sl->vaddr;
 		}
-		KASSERT(pa == (VM_PAGE_TO_PHYS(m) | offset),
-		    ("unexpected vm_page_t phys: 0x%08x != 0x%08x",
-		    VM_PAGE_TO_PHYS(m) | offset, pa));
 
 		switch (op) {
 		case BUS_DMASYNC_PREWRITE: