On all the architectures, avoid to preallocate the physical memory

for nodes used in vm_radix.
On architectures supporting direct mapping, also avoid to pre-allocate
the KVA for such nodes.

In order to do so make the operations derived from vm_radix_insert()
to fail and handle all the deriving failure of those.

vm_radix-wise introduce a new function called vm_radix_replace(),
which can replace a leaf node, already present, with a new one,
and take into account the possibility, during vm_radix_insert()
allocation, that the operations on the radix trie can recurse.
This means that if operations in vm_radix_insert() recursed
vm_radix_insert() will start from scratch again.

Sponsored by:	EMC / Isilon storage division
Reviewed by:	alc (older version)
Reviewed by:	jeff
Tested by:	pho, scottl

1 files changed, 4 insertions, 0 deletions

diff --git a/sys/vm/_vm_radix.h b/sys/vm/_vm_radix.h
index f066462..1d06d0a 100644
--- a/sys/vm/_vm_radix.h
+++ b/sys/vm/_vm_radix.h
@@ -36,8 +36,12 @@
  */
 struct vm_radix {
 	uintptr_t	rt_root;
+	uint8_t		rt_flags;
 };
 
+#define	RT_INSERT_INPROG	0x01
+#define	RT_TRIE_MODIFIED	0x02
+
 #ifdef _KERNEL
 
 static __inline boolean_t