staging: zsmalloc: zsmalloc memory allocation library

This patch creates a new memory allocation library named
zsmalloc.

NOTE: zsmalloc currently depends on SPARSEMEM for the MAX_PHYSMEM_BITS
value needed to determine the format of the object handle. There may
be a better way to do this.  Feedback is welcome.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/zsmalloc/Kconfig

@@ -0,0 +1,11 @@
+config ZSMALLOC
+	tristate "Memory allocator for compressed pages"
+	depends on SPARSEMEM
+	default n
+	help
+	  zsmalloc is a slab-based memory allocator designed to store
+	  compressed RAM pages.  zsmalloc uses virtual memory mapping
+	  in order to reduce fragmentation.  However, this results in a
+	  non-standard allocator interface where a handle, not a pointer, is
+	  returned by an alloc().  This handle must be mapped in order to
+	  access the allocated space.

drivers/staging/zsmalloc/Makefile

@@ -0,0 +1,3 @@
+zsmalloc-y 		:= zsmalloc-main.o
+
+obj-$(CONFIG_ZSMALLOC)	+= zsmalloc.o