* Removed the page state PAGE_STATE_BUSY and instead introduced a vm_page::busy

flag. The obvious advantage is that one can still see what state a page is in
  and even move it between states while being marked busy.
* Removed the vm_page::is_dummy flag. Instead we mark marker pages busy, which
  in all cases has the same effect. Introduced a vm_page_is_dummy() that can
  still check whether a given page is a dummy page.
* vm_page_unreserve_pages(): Before adding to the system reserve make sure
  sUnreservedFreePages is non-negative. Otherwise we'd make nonexisting pages
  available for allocation. steal_pages() still has the same problem and it
  can't be solved that easily.
* map_page(): No longer changes the page state/mark the page unbusy. That's the
  caller's responsibility.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35331 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/slab/MemoryManager.cpp

@@ -1352,6 +1352,7 @@ MemoryManager::_MapChunk(VMArea* vmArea, addr_t address, size_t size,
 		vm_page* page = vm_page_allocate_page(PAGE_STATE_FREE);
 		cache->InsertPage(page, offset);
 		vm_page_set_state(page, PAGE_STATE_WIRED);
+		page->busy = false;
 
 		page->wired_count++;
 		atomic_add(&gMappedPagesCount, 1);