#define VM_EXEC 0x00000004
#define VM_SHARED 0x00000008
+/* mprotect() hardcodes VM_MAYREAD >> 4 == VM_READ, and so for r/w/x bits. */
#define VM_MAYREAD 0x00000010 /* limits for mprotect() etc */
#define VM_MAYWRITE 0x00000020
#define VM_MAYEXEC 0x00000040
* only one copy in memory, at most, normally.
*
* For the non-reserved pages, page_count(page) denotes a reference count.
- * page_count() == 0 means the page is free.
+ * page_count() == 0 means the page is free. page->lru is then used for
+ * freelist management in the buddy allocator.
* page_count() == 1 means the page is used for exactly one purpose
* (e.g. a private data page of one process).
*
* attaches, plus 1 if `private' contains something, plus one for
* the page cache itself.
*
- * All pages belonging to an inode are in these doubly linked lists:
- * mapping->clean_pages, mapping->dirty_pages and mapping->locked_pages;
- * using the page->list list_head. These fields are also used for
- * freelist managemet (when page_count()==0).
+ * Instead of keeping dirty/clean pages in per address-space lists, we instead
+ * now tag pages as dirty/under writeback in the radix tree.
*
* There is also a per-mapping radix tree mapping index to the page
* in memory if present. The tree is rooted at mapping->root.