Index: sys/arch/arm/arm32/bus_dma.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/arm32/bus_dma.c,v
retrieving revision 1.121
diff -u -p -r1.121 bus_dma.c
--- sys/arch/arm/arm32/bus_dma.c	14 Mar 2020 18:08:38 -0000	1.121
+++ sys/arch/arm/arm32/bus_dma.c	26 Mar 2020 08:37:09 -0000
@@ -40,7 +40,9 @@ __KERNEL_RCSID(0, "$NetBSD: bus_dma.c,v 
 
 #include <sys/param.h>
 #include <sys/bus.h>
+#include <sys/cprng.h>
 #include <sys/cpu.h>
+#include <sys/kernel.h>
 #include <sys/kmem.h>
 #include <sys/mbuf.h>
 
@@ -1384,6 +1386,8 @@ _bus_dmamem_map(bus_dma_tag_t t, bus_dma
 #endif
 
 	size = round_page(size);
+// 	if (size > PAGE_SIZE)
+// 		fragmented = true;
 
 #ifdef PMAP_MAPSIZE1
 	if (size >= PMAP_MAPSIZE1)
@@ -1599,8 +1603,10 @@ _bus_dmamem_alloc_range(bus_dma_tag_t t,
 {
 	paddr_t curaddr, lastaddr;
 	struct vm_page *m;
+	struct vm_page *hole = NULL;
 	struct pglist mlist;
 	int curseg, error;
+	bool fragment = false;
 
 	KASSERTMSG(boundary == 0 || (boundary & (boundary - 1)) == 0,
 	    "invalid boundary %#lx", boundary);
@@ -1612,6 +1618,10 @@ _bus_dmamem_alloc_range(bus_dma_tag_t t,
 
 	/* Always round the size. */
 	size = round_page(size);
+	if (!cold && size > PAGE_SIZE) {
+		size += PAGE_SIZE;
+		fragment = true;
+	}
 
 	/*
 	 * We accept boundaries < size, splitting in multiple segments
@@ -1635,6 +1645,7 @@ _bus_dmamem_alloc_range(bus_dma_tag_t t,
 	if (error)
 		return error;
 
+	bool split = false;
 	/*
 	 * Compute the location, size, and number of segments actually
 	 * returned by the VM code.
@@ -1669,8 +1680,16 @@ _bus_dmamem_alloc_range(bus_dma_tag_t t,
 			segs[curseg].ds_len = PAGE_SIZE;
 		}
 		lastaddr = curaddr;
-	}
 
+		if (fragment && !split && (cprng_fast32() & 1) == 0) {
+			m = TAILQ_NEXT(m, pageq.queue);
+			hole = m;
+			split = true;
+		}
+	}
+	if (fragment) {
+		printf("%s: hole %p\n", __func__, hole);
+	}
 	*rsegs = curseg + 1;
 
 	return 0;