- Introduce the new M_NOVM option which tells uma to only check the currently

allocated slabs and bucket caches for free items.  It will not go ask the vm
  for pages.  This differs from M_NOWAIT in that it not only doesn't block, it
  doesn't even ask.

- Add a new zcreate option ZONE_VM, that sets the BUCKETCACHE zflag.  This
  tells uma that it should only allocate buckets out of the bucket cache, and
  not from the VM.  It does this by using the M_NOVM option to zalloc when
  getting a new bucket.  This is so that the VM doesn't recursively enter
  itself while trying to allocate buckets for vm_map_entry zones.  If there
  are already allocated buckets when we get here we'll still use them but
  otherwise we'll skip it.

- Use the ZONE_VM flag on vm map entries and pv entries on x86.

sys/amd64/amd64/pmap.c

@@ -485,7 +485,7 @@ pmap_init(phys_start, phys_end)
 	if (initial_pvs < MINPV)
 		initial_pvs = MINPV;
 	pvzone = uma_zcreate("PV ENTRY", sizeof (struct pv_entry), NULL, NULL, 
-	    NULL, NULL, UMA_ALIGN_PTR, 0);
+	    NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM);
 	uma_zone_set_allocf(pvzone, pmap_allocf);
 	uma_prealloc(pvzone, initial_pvs);
 

sys/i386/i386/pmap.c

@@ -485,7 +485,7 @@ pmap_init(phys_start, phys_end)
 	if (initial_pvs < MINPV)
 		initial_pvs = MINPV;
 	pvzone = uma_zcreate("PV ENTRY", sizeof (struct pv_entry), NULL, NULL, 
-	    NULL, NULL, UMA_ALIGN_PTR, 0);
+	    NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM);
 	uma_zone_set_allocf(pvzone, pmap_allocf);
 	uma_prealloc(pvzone, initial_pvs);
 

sys/sys/malloc.h

@@ -52,6 +52,7 @@
 #define	M_NOWAIT	0x0001		/* do not block */
 #define	M_USE_RESERVE	0x0002		/* can alloc out of reserve memory */
 #define	M_ZERO		0x0004		/* bzero the allocation */
+#define M_NOVM		0x0008		/* Don't ask the VM for pages */
 
 #define	M_MAGIC		877983977	/* time when first defined :-) */
 

sys/vm/uma.h

@@ -173,6 +173,7 @@ uma_zone_t uma_zcreate(char *name, size_t size, uma_ctor ctor, uma_dtor dtor,
 #define UMA_ZONE_MALLOC		0x0010	/* For use by malloc(9) only! */
 #define UMA_ZONE_NOFREE		0x0020	/* Do not free slabs of this type! */
 #define UMA_ZONE_MTXCLASS	0x0040	/* Create a new lock class */
+#define	UMA_ZONE_VM		0x0080	/* Used for internal vm datastructures */
 
 /* Definitions for align */
 #define UMA_ALIGN_PTR	(sizeof(void *) - 1)	/* Alignment fit for ptr */

sys/vm/uma_core.c

@@ -1013,6 +1013,9 @@ zone_ctor(void *mem, int size, void *udata)
 	if (arg->flags & UMA_ZONE_NOFREE)
 		zone->uz_flags |= UMA_ZFLAG_NOFREE;
 
+	if (arg->flags & UMA_ZONE_VM)
+		zone->uz_flags |= UMA_ZFLAG_BUCKETCACHE;
+
 	if (zone->uz_size > UMA_SLAB_SIZE)
 		zone_large_init(zone);
 	else
@@ -1417,9 +1420,16 @@ uma_zalloc_arg(uma_zone_t zone, void *udata, int flags)
 	/* Now we no longer need the zone lock. */
 	ZONE_UNLOCK(zone);
 
-	if (bucket == NULL)
+	if (bucket == NULL) {
+		int bflags;
+
+		bflags = flags;
+		if (zone->uz_flags & UMA_ZFLAG_BUCKETCACHE)
+			bflags |= M_NOVM;
+
 		bucket = uma_zalloc_internal(bucketzone,
-		    NULL, flags, NULL);
+		    NULL, bflags, NULL);
+	}
 
 	if (bucket != NULL) {
 #ifdef INVARIANTS
@@ -1524,7 +1534,8 @@ uma_zalloc_internal(uma_zone_t zone, void *udata, int flags, uma_bucket_t bucket
 		 * and cause the vm to allocate vm_map_entries.  If we need new
 		 * buckets there too we will recurse in kmem_alloc and bad 
 		 * things happen.  So instead we return a NULL bucket, and make
-		 * the code that allocates buckets smart enough to deal with it			 */ 
+		 * the code that allocates buckets smart enough to deal with it
+		 */ 
 		if (zone == bucketzone && zone->uz_recurse != 0) {
 			ZONE_UNLOCK(zone);
 			return (NULL);
@@ -1541,6 +1552,9 @@ uma_zalloc_internal(uma_zone_t zone, void *udata, int flags, uma_bucket_t bucket
 			goto new_slab;
 		}
 
+		if (flags & M_NOVM)
+			goto alloc_fail;
+
 		zone->uz_recurse++;
 		slab = slab_zalloc(zone, flags);
 		zone->uz_recurse--;

sys/vm/uma_int.h

@@ -273,6 +273,7 @@ struct uma_zone {
 #define UMA_ZFLAG_MALLOC	0x0008	/* Zone created by malloc */
 #define UMA_ZFLAG_NOFREE	0x0010	/* Don't free data from this zone */
 #define UMA_ZFLAG_FULL		0x0020	/* This zone reached uz_maxpages */
+#define UMA_ZFLAG_BUCKETCACHE	0x0040	/* Only allocate buckets from cache */
 
 /* This lives in uflags */
 #define UMA_ZONE_INTERNAL	0x1000	/* Internal zone for uflags */

sys/vm/vm_map.c

@@ -159,7 +159,8 @@ vm_map_startup(void)
 	    vm_map_zinit, vm_map_zfini, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
 	uma_prealloc(mapzone, MAX_KMAP);
 	kmapentzone = uma_zcreate("KMAP ENTRY", sizeof(struct vm_map_entry), 
-	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_MTXCLASS);
+	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,
+	    UMA_ZONE_MTXCLASS | UMA_ZONE_VM);
 	uma_prealloc(kmapentzone, MAX_KMAPENT);
 	mapentzone = uma_zcreate("MAP ENTRY", sizeof(struct vm_map_entry), 
 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);