Index: graphics/drm-next-kmod/Makefile
===================================================================
--- graphics/drm-next-kmod/Makefile
+++ graphics/drm-next-kmod/Makefile
@@ -3,7 +3,7 @@
 
 PORTNAME=	drm-next-kmod
 PORTVERSION=	4.11.g20181027
-PORTREVISION=	1
+PORTREVISION=	2
 CATEGORIES=	graphics
 
 MAINTAINER=	jmd@FreeBSD.org
Index: graphics/drm-next-kmod/files/patch-drm__ttm__ttm_memory.c
===================================================================
--- /dev/null
+++ graphics/drm-next-kmod/files/patch-drm__ttm__ttm_memory.c
@@ -0,0 +1,51 @@
+--- drm/ttm/ttm_memory.c.orig	2018-10-25 02:29:04.000000000 -0700
++++ drm/ttm/ttm_memory.c
+@@ -263,6 +263,9 @@
+ #ifdef __linux__
+ 	uint64_t mem;
+ #endif
++#ifdef __FreeBSD__
++	uint64_t maxmem;
++#endif
+ 	int ret;
+ 
+ 	if (unlikely(!zone))
+@@ -274,6 +277,16 @@
+ #endif
+ 
+ 	zone->name = "kernel";
++#ifdef __FreeBSD__
++	/*
++	 * As a hack workaround for the lack of good backpressure system
++	 * between FreeBSD pagedaemon and the TTM cache, just allow users to
++	 * impose an arbitrary limit on the big TTM cache size.
++	 */
++	if (getenv_uint64("dev.drm.ttm_kernel_zone_maxmem", &maxmem) &&
++	    (mem >> 1) > maxmem)
++		mem = maxmem << 1;
++#endif
+ 	zone->zone_mem = mem;
+ 	zone->max_mem = mem >> 1;
+ 	zone->emer_mem = (mem >> 1) + (mem >> 2);
+@@ -339,6 +352,9 @@
+ #ifdef __linux__
+ 	uint64_t mem;
+ #endif
++#ifdef __FreeBSD__
++	uint64_t maxmem;
++#endif
+ 	int ret;
+ 
+ 	if (unlikely(!zone))
+@@ -366,6 +382,11 @@
+ 
+ 	mem = ((uint64_t) 1ULL << 32);
+ 	zone->name = "dma32";
++#ifdef __FreeBSD__
++	if (getenv_uint64("dev.drm.ttm_dma32_zone_maxmem", &maxmem) &&
++	    (mem >> 1) > maxmem)
++		mem = maxmem << 1;
++#endif
+ 	zone->zone_mem = mem;
+ 	zone->max_mem = mem >> 1;
+ 	zone->emer_mem = (mem >> 1) + (mem >> 2);
Index: graphics/drm-next-kmod/pkg-message
===================================================================
--- graphics/drm-next-kmod/pkg-message
+++ graphics/drm-next-kmod/pkg-message
@@ -13,3 +13,14 @@
 
 Older generations are supported by the legacy kms modules (radeonkms / 
 i915kms) in base or by installing graphics/drm-legacy-kmod.
+
+The radeon and amdgpu drivers rely on a memory backpressure system to release
+memory when the system is at capacity.  Currently, the integration between
+native FreeBSD memory pressure and that linuxkpi subsystem is poor.  The
+symptom of this condition is top(1) showing about half of memory in the "Wired"
+state, as well as low Free and Buffer cache numbers and regular allocation
+failures (i.e., "swap_pager_getswapspace(...): failed" in dmesg(8)).
+
+As a short-term workaround, radeon and amdgpu users can set the tunables
+"dev.drm.ttm_dma32_zone_maxmem" and "dev.drm.ttm_kernel_zone_maxmem" to limit
+the maximum memory (in bytes) used by the corresponding zones.