page migration reorg patch

page migration reorg patch

[Christoph Lameter]

This patch centralizes the page migration functions in anticipation of 
additional tinkering. Creates a new file mm/migrate.c

1. Extract buffer_migrate_page() from fs/buffer.c

2. Extract central migration code from vmscan.c

3. Extract some components from mempolicy.c

4. Export pageout() and remove_from_swap() from vmscan.c

5. Make it possible to configure NUMA systems without page migration
   and non-NUMA systems with page migration.

I had to so some #ifdeffing in mempolicy.c that may need a cleanup.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.16-rc6/mm/Makefile
===================================================================
--- linux-2.6.16-rc6.orig/mm/Makefile	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/mm/Makefile	2006-03-15 17:23:42.000000000 -0800
@@ -22,3 +22,5 @@ obj-$(CONFIG_SLOB) += slob.o
 obj-$(CONFIG_SLAB) += slab.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
 obj-$(CONFIG_FS_XIP) += filemap_xip.o
+obj-$(CONFIG_MIGRATION) += migrate.o
+
Index: linux-2.6.16-rc6/mm/migrate.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.16-rc6/mm/migrate.c	2006-03-15 17:35:49.000000000 -0800
@@ -0,0 +1,620 @@
+/*
+ * Memory Migration functionality - linux/mm/migration.c
+ *
+ * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
+ *
+ * Page migration was first developed in the context of the memory hotplug
+ * project. The main authors of the migration code are:
+ *
+ * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
+ * Hirokazu Takahashi <taka@valinux.co.jp>
+ * Dave Hansen <haveblue@us.ibm.com>
+ * Christoph Lameter <clameter@sgi.com>
+ */
+
+#include <linux/migrate.h>
+#include <linux/module.h>
+#include <linux/swap.h>
+#include <linux/pagemap.h>
+#include <linux/buffer_head.h>	/* for try_to_release_page(),
+					buffer_heads_over_limit */
+#include <linux/mm_inline.h>
+#include <linux/pagevec.h>
+#include <linux/rmap.h>
+#include <linux/topology.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/swapops.h>
+
+/* The maximum number of pages to take off the LRU for migration */
+#define MIGRATE_CHUNK_SIZE 256
+
+#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
+
+static inline void move_to_lru(struct page *page)
+{
+	list_del(&page->lru);
+	if (PageActive(page)) {
+		/*
+		 * lru_cache_add_active checks that
+		 * the PG_active bit is off.
+		 */
+		ClearPageActive(page);
+		lru_cache_add_active(page);
+	} else {
+		lru_cache_add(page);
+	}
+	put_page(page);
+}
+
+/*
+ * Add isolated pages on the list back to the LRU.
+ *
+ * returns the number of pages put back.
+ */
+int putback_lru_pages(struct list_head *l)
+{
+	struct page *page;
+	struct page *page2;
+	int count = 0;
+
+	list_for_each_entry_safe(page, page2, l, lru) {
+		move_to_lru(page);
+		count++;
+	}
+	return count;
+}
+
+/*
+ * Non migratable page
+ */
+int fail_migrate_page(struct page *newpage, struct page *page)
+{
+	return -EIO;
+}
+EXPORT_SYMBOL(fail_migrate_page);
+
+/*
+ * swapout a single page
+ * page is locked upon entry, unlocked on exit
+ */
+static int swap_page(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+
+	if (page_mapped(page) && mapping)
+		if (try_to_unmap(page, 1) != SWAP_SUCCESS)
+			goto unlock_retry;
+
+	if (PageDirty(page)) {
+		/* Page is dirty, try to write it out here */
+		switch(pageout(page, mapping)) {
+		case PAGE_KEEP:
+		case PAGE_ACTIVATE:
+			goto unlock_retry;
+
+		case PAGE_SUCCESS:
+			goto retry;
+
+		case PAGE_CLEAN:
+			; /* try to free the page below */
+		}
+	}
+
+	if (PagePrivate(page)) {
+		if (!try_to_release_page(page, GFP_KERNEL) ||
+		    (!mapping && page_count(page) == 1))
+			goto unlock_retry;
+	}
+
+	if (remove_mapping(mapping, page)) {
+		/* Success */
+		unlock_page(page);
+		return 0;
+	}
+
+unlock_retry:
+	unlock_page(page);
+
+retry:
+	return -EAGAIN;
+}
+EXPORT_SYMBOL(swap_page);
+
+/*
+ * Remove references for a page and establish the new page with the correct
+ * basic settings to be able to stop accesses to the page.
+ */
+int migrate_page_remove_references(struct page *newpage,
+				struct page *page, int nr_refs)
+{
+	struct address_space *mapping = page_mapping(page);
+	struct page **radix_pointer;
+
+	/*
+	 * Avoid doing any of the following work if the page count
+	 * indicates that the page is in use or truncate has removed
+	 * the page.
+	 */
+	if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
+		return 1;
+
+	/*
+	 * Establish swap ptes for anonymous pages or destroy pte
+	 * maps for files.
+	 *
+	 * In order to reestablish file backed mappings the fault handlers
+	 * will take the radix tree_lock which may then be used to stop
+  	 * processses from accessing this page until the new page is ready.
+	 *
+	 * A process accessing via a swap pte (an anonymous page) will take a
+	 * page_lock on the old page which will block the process until the
+	 * migration attempt is complete. At that time the PageSwapCache bit
+	 * will be examined. If the page was migrated then the PageSwapCache
+	 * bit will be clear and the operation to retrieve the page will be
+	 * retried which will find the new page in the radix tree. Then a new
+	 * direct mapping may be generated based on the radix tree contents.
+	 *
+	 * If the page was not migrated then the PageSwapCache bit
+	 * is still set and the operation may continue.
+	 */
+	try_to_unmap(page, 1);
+
+	/*
+	 * Give up if we were unable to remove all mappings.
+	 */
+	if (page_mapcount(page))
+		return 1;
+
+	write_lock_irq(&mapping->tree_lock);
+
+	radix_pointer = (struct page **)radix_tree_lookup_slot(
+						&mapping->page_tree,
+						page_index(page));
+
+	if (!page_mapping(page) || page_count(page) != nr_refs ||
+			*radix_pointer != page) {
+		write_unlock_irq(&mapping->tree_lock);
+		return 1;
+	}
+
+	/*
+	 * Now we know that no one else is looking at the page.
+	 *
+	 * Certain minimal information about a page must be available
+	 * in order for other subsystems to properly handle the page if they
+	 * find it through the radix tree update before we are finished
+	 * copying the page.
+	 */
+	get_page(newpage);
+	newpage->index = page->index;
+	newpage->mapping = page->mapping;
+	if (PageSwapCache(page)) {
+		SetPageSwapCache(newpage);
+		set_page_private(newpage, page_private(page));
+	}
+
+	*radix_pointer = newpage;
+	__put_page(page);
+	write_unlock_irq(&mapping->tree_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(migrate_page_remove_references);
+
+/*
+ * Copy the page to its new location
+ */
+void migrate_page_copy(struct page *newpage, struct page *page)
+{
+	copy_highpage(newpage, page);
+
+	if (PageError(page))
+		SetPageError(newpage);
+	if (PageReferenced(page))
+		SetPageReferenced(newpage);
+	if (PageUptodate(page))
+		SetPageUptodate(newpage);
+	if (PageActive(page))
+		SetPageActive(newpage);
+	if (PageChecked(page))
+		SetPageChecked(newpage);
+	if (PageMappedToDisk(page))
+		SetPageMappedToDisk(newpage);
+
+	if (PageDirty(page)) {
+		clear_page_dirty_for_io(page);
+		set_page_dirty(newpage);
+ 	}
+
+	ClearPageSwapCache(page);
+	ClearPageActive(page);
+	ClearPagePrivate(page);
+	set_page_private(page, 0);
+	page->mapping = NULL;
+
+	/*
+	 * If any waiters have accumulated on the new page then
+	 * wake them up.
+	 */
+	if (PageWriteback(newpage))
+		end_page_writeback(newpage);
+}
+EXPORT_SYMBOL(migrate_page_copy);
+
+/*
+ * Common logic to directly migrate a single page suitable for
+ * pages that do not use PagePrivate.
+ *
+ * Pages are locked upon entry and exit.
+ */
+int migrate_page(struct page *newpage, struct page *page)
+{
+	BUG_ON(PageWriteback(page));	/* Writeback must be complete */
+
+	if (migrate_page_remove_references(newpage, page, 2))
+		return -EAGAIN;
+
+	migrate_page_copy(newpage, page);
+
+	/*
+	 * Remove auxiliary swap entries and replace
+	 * them with real ptes.
+	 *
+	 * Note that a real pte entry will allow processes that are not
+	 * waiting on the page lock to use the new page via the page tables
+	 * before the new page is unlocked.
+	 */
+	remove_from_swap(newpage);
+	return 0;
+}
+EXPORT_SYMBOL(migrate_page);
+
+/*
+ * migrate_pages
+ *
+ * Two lists are passed to this function. The first list
+ * contains the pages isolated from the LRU to be migrated.
+ * The second list contains new pages that the pages isolated
+ * can be moved to. If the second list is NULL then all
+ * pages are swapped out.
+ *
+ * The function returns after 10 attempts or if no pages
+ * are movable anymore because to has become empty
+ * or no retryable pages exist anymore.
+ *
+ * Return: Number of pages not migrated when "to" ran empty.
+ */
+int migrate_pages(struct list_head *from, struct list_head *to,
+		  struct list_head *moved, struct list_head *failed)
+{
+	int retry;
+	int nr_failed = 0;
+	int pass = 0;
+	struct page *page;
+	struct page *page2;
+	int swapwrite = current->flags & PF_SWAPWRITE;
+	int rc;
+
+	if (!swapwrite)
+		current->flags |= PF_SWAPWRITE;
+
+redo:
+	retry = 0;
+
+	list_for_each_entry_safe(page, page2, from, lru) {
+		struct page *newpage = NULL;
+		struct address_space *mapping;
+
+		cond_resched();
+
+		rc = 0;
+		if (page_count(page) == 1)
+			/* page was freed from under us. So we are done. */
+			goto next;
+
+		if (to && list_empty(to))
+			break;
+
+		/*
+		 * Skip locked pages during the first two passes to give the
+		 * functions holding the lock time to release the page. Later we
+		 * use lock_page() to have a higher chance of acquiring the
+		 * lock.
+		 */
+		rc = -EAGAIN;
+		if (pass > 2)
+			lock_page(page);
+		else
+			if (TestSetPageLocked(page))
+				goto next;
+
+		/*
+		 * Only wait on writeback if we have already done a pass where
+		 * we we may have triggered writeouts for lots of pages.
+		 */
+		if (pass > 0) {
+			wait_on_page_writeback(page);
+		} else {
+			if (PageWriteback(page))
+				goto unlock_page;
+		}
+
+		/*
+		 * Anonymous pages must have swap cache references otherwise
+		 * the information contained in the page maps cannot be
+		 * preserved.
+		 */
+		if (PageAnon(page) && !PageSwapCache(page)) {
+			if (!add_to_swap(page, GFP_KERNEL)) {
+				rc = -ENOMEM;
+				goto unlock_page;
+			}
+		}
+
+		if (!to) {
+			rc = swap_page(page);
+			goto next;
+		}
+
+		newpage = lru_to_page(to);
+		lock_page(newpage);
+
+		/*
+		 * Pages are properly locked and writeback is complete.
+		 * Try to migrate the page.
+		 */
+		mapping = page_mapping(page);
+		if (!mapping)
+			goto unlock_both;
+
+		if (mapping->a_ops->migratepage) {
+			/*
+			 * Most pages have a mapping and most filesystems
+			 * should provide a migration function. Anonymous
+			 * pages are part of swap space which also has its
+			 * own migration function. This is the most common
+			 * path for page migration.
+			 */
+			rc = mapping->a_ops->migratepage(newpage, page);
+			goto unlock_both;
+                }
+
+		/*
+		 * Default handling if a filesystem does not provide
+		 * a migration function. We can only migrate clean
+		 * pages so try to write out any dirty pages first.
+		 */
+		if (PageDirty(page)) {
+			switch (pageout(page, mapping)) {
+			case PAGE_KEEP:
+			case PAGE_ACTIVATE:
+				goto unlock_both;
+
+			case PAGE_SUCCESS:
+				unlock_page(newpage);
+				goto next;
+
+			case PAGE_CLEAN:
+				; /* try to migrate the page below */
+			}
+                }
+
+		/*
+		 * Buffers are managed in a filesystem specific way.
+		 * We must have no buffers or drop them.
+		 */
+		if (!page_has_buffers(page) ||
+		    try_to_release_page(page, GFP_KERNEL)) {
+			rc = migrate_page(newpage, page);
+			goto unlock_both;
+		}
+
+		/*
+		 * On early passes with mapped pages simply
+		 * retry. There may be a lock held for some
+		 * buffers that may go away. Later
+		 * swap them out.
+		 */
+		if (pass > 4) {
+			/*
+			 * Persistently unable to drop buffers..... As a
+			 * measure of last resort we fall back to
+			 * swap_page().
+			 */
+			unlock_page(newpage);
+			newpage = NULL;
+			rc = swap_page(page);
+			goto next;
+		}
+
+unlock_both:
+		unlock_page(newpage);
+
+unlock_page:
+		unlock_page(page);
+
+next:
+		if (rc == -EAGAIN) {
+			retry++;
+		} else if (rc) {
+			/* Permanent failure */
+			list_move(&page->lru, failed);
+			nr_failed++;
+		} else {
+			if (newpage) {
+				/* Successful migration. Return page to LRU */
+				move_to_lru(newpage);
+			}
+			list_move(&page->lru, moved);
+		}
+	}
+	if (retry && pass++ < 10)
+		goto redo;
+
+	if (!swapwrite)
+		current->flags &= ~PF_SWAPWRITE;
+
+	return nr_failed + retry;
+}
+
+/*
+ * Isolate one page from the LRU lists and put it on the
+ * indicated list with elevated refcount.
+ *
+ * Result:
+ *  0 = page not on LRU list
+ *  1 = page removed from LRU list and added to the specified list.
+ */
+int isolate_lru_page(struct page *page)
+{
+	int ret = 0;
+
+	if (PageLRU(page)) {
+		struct zone *zone = page_zone(page);
+		spin_lock_irq(&zone->lru_lock);
+		if (TestClearPageLRU(page)) {
+			ret = 1;
+			get_page(page);
+			if (PageActive(page))
+				del_page_from_active_list(zone, page);
+			else
+				del_page_from_inactive_list(zone, page);
+		}
+		spin_unlock_irq(&zone->lru_lock);
+	}
+
+	return ret;
+}
+
+/*
+ * Migration function for pages with buffers. This function can only be used
+ * if the underlying filesystem guarantees that no other references to "page"
+ * exist.
+ */
+int buffer_migrate_page(struct page *newpage, struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct buffer_head *bh, *head;
+
+	if (!mapping)
+		return -EAGAIN;
+
+	if (!page_has_buffers(page))
+		return migrate_page(newpage, page);
+
+	head = page_buffers(page);
+
+	if (migrate_page_remove_references(newpage, page, 3))
+		return -EAGAIN;
+
+	bh = head;
+	do {
+		get_bh(bh);
+		lock_buffer(bh);
+		bh = bh->b_this_page;
+
+	} while (bh != head);
+
+	ClearPagePrivate(page);
+	set_page_private(newpage, page_private(page));
+	set_page_private(page, 0);
+	put_page(page);
+	get_page(newpage);
+
+	bh = head;
+	do {
+		set_bh_page(bh, newpage, bh_offset(bh));
+		bh = bh->b_this_page;
+
+	} while (bh != head);
+
+	SetPagePrivate(newpage);
+
+	migrate_page_copy(newpage, page);
+
+	bh = head;
+	do {
+		unlock_buffer(bh);
+ 		put_bh(bh);
+		bh = bh->b_this_page;
+
+	} while (bh != head);
+
+	return 0;
+}
+EXPORT_SYMBOL(buffer_migrate_page);
+
+#ifdef CONFIG_NUMA
+/*
+ * Migrate the list 'pagelist' of pages to a certain destination.
+ *
+ * Specify destination with either non-NULL vma or dest_node >= 0
+ * Return the number of pages not migrated or error code
+ */
+int migrate_pages_to(struct list_head *pagelist,
+			struct vm_area_struct *vma, int dest)
+{
+	LIST_HEAD(newlist);
+	LIST_HEAD(moved);
+	LIST_HEAD(failed);
+	int err = 0;
+	unsigned long offset = 0;
+	int nr_pages;
+	struct page *page;
+	struct list_head *p;
+
+redo:
+	nr_pages = 0;
+	list_for_each(p, pagelist) {
+		if (vma) {
+			/*
+			 * The address passed to alloc_page_vma is used to
+			 * generate the proper interleave behavior. We fake
+			 * the address here by an increasing offset in order
+			 * to get the proper distribution of pages.
+			 *
+			 * No decision has been made as to which page
+			 * a certain old page is moved to so we cannot
+			 * specify the correct address.
+			 */
+			page = alloc_page_vma(GFP_HIGHUSER, vma,
+					offset + vma->vm_start);
+			offset += PAGE_SIZE;
+		}
+		else
+			page = alloc_pages_node(dest, GFP_HIGHUSER, 0);
+
+		if (!page) {
+			err = -ENOMEM;
+			goto out;
+		}
+		list_add_tail(&page->lru, &newlist);
+		nr_pages++;
+		if (nr_pages > MIGRATE_CHUNK_SIZE)
+			break;
+	}
+	err = migrate_pages(pagelist, &newlist, &moved, &failed);
+
+	putback_lru_pages(&moved);	/* Call release pages instead ?? */
+
+	if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist))
+		goto redo;
+out:
+	/* Return leftover allocated pages */
+	while (!list_empty(&newlist)) {
+		page = list_entry(newlist.next, struct page, lru);
+		list_del(&page->lru);
+		__free_page(page);
+	}
+	list_splice(&failed, pagelist);
+	if (err < 0)
+		return err;
+
+	/* Calculate number of leftover pages */
+	nr_pages = 0;
+	list_for_each(p, pagelist)
+		nr_pages++;
+	return nr_pages;
+}
+#endif
Index: linux-2.6.16-rc6/mm/vmscan.c
===================================================================
--- linux-2.6.16-rc6.orig/mm/vmscan.c	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/mm/vmscan.c	2006-03-15 16:43:32.000000000 -0800
@@ -39,18 +39,6 @@
 
 #include <linux/swapops.h>
 
-/* possible outcome of pageout() */
-typedef enum {
-	/* failed to write page out, page is locked */
-	PAGE_KEEP,
-	/* move page to the active list, page is locked */
-	PAGE_ACTIVATE,
-	/* page has been sent to the disk successfully, page is unlocked */
-	PAGE_SUCCESS,
-	/* page is clean and locked */
-	PAGE_CLEAN,
-} pageout_t;
-
 struct scan_control {
 	/* Ask refill_inactive_zone, or shrink_cache to scan this many pages */
 	unsigned long nr_to_scan;
@@ -308,7 +296,7 @@ static void handle_write_error(struct ad
 /*
  * pageout is called by shrink_list() for each dirty page. Calls ->writepage().
  */
-static pageout_t pageout(struct page *page, struct address_space *mapping)
+pageout_t pageout(struct page *page, struct address_space *mapping)
 {
 	/*
 	 * If the page is dirty, only perform writeback if that write
@@ -376,7 +364,7 @@ static pageout_t pageout(struct page *pa
 	return PAGE_CLEAN;
 }
 
-static int remove_mapping(struct address_space *mapping, struct page *page)
+int remove_mapping(struct address_space *mapping, struct page *page)
 {
 	if (!mapping)
 		return 0;		/* truncate got there first */
@@ -583,474 +571,6 @@ keep:
 	return reclaimed;
 }
 
-#ifdef CONFIG_MIGRATION
-static inline void move_to_lru(struct page *page)
-{
-	list_del(&page->lru);
-	if (PageActive(page)) {
-		/*
-		 * lru_cache_add_active checks that
-		 * the PG_active bit is off.
-		 */
-		ClearPageActive(page);
-		lru_cache_add_active(page);
-	} else {
-		lru_cache_add(page);
-	}
-	put_page(page);
-}
-
-/*
- * Add isolated pages on the list back to the LRU.
- *
- * returns the number of pages put back.
- */
-int putback_lru_pages(struct list_head *l)
-{
-	struct page *page;
-	struct page *page2;
-	int count = 0;
-
-	list_for_each_entry_safe(page, page2, l, lru) {
-		move_to_lru(page);
-		count++;
-	}
-	return count;
-}
-
-/*
- * Non migratable page
- */
-int fail_migrate_page(struct page *newpage, struct page *page)
-{
-	return -EIO;
-}
-EXPORT_SYMBOL(fail_migrate_page);
-
-/*
- * swapout a single page
- * page is locked upon entry, unlocked on exit
- */
-static int swap_page(struct page *page)
-{
-	struct address_space *mapping = page_mapping(page);
-
-	if (page_mapped(page) && mapping)
-		if (try_to_unmap(page, 1) != SWAP_SUCCESS)
-			goto unlock_retry;
-
-	if (PageDirty(page)) {
-		/* Page is dirty, try to write it out here */
-		switch(pageout(page, mapping)) {
-		case PAGE_KEEP:
-		case PAGE_ACTIVATE:
-			goto unlock_retry;
-
-		case PAGE_SUCCESS:
-			goto retry;
-
-		case PAGE_CLEAN:
-			; /* try to free the page below */
-		}
-	}
-
-	if (PagePrivate(page)) {
-		if (!try_to_release_page(page, GFP_KERNEL) ||
-		    (!mapping && page_count(page) == 1))
-			goto unlock_retry;
-	}
-
-	if (remove_mapping(mapping, page)) {
-		/* Success */
-		unlock_page(page);
-		return 0;
-	}
-
-unlock_retry:
-	unlock_page(page);
-
-retry:
-	return -EAGAIN;
-}
-EXPORT_SYMBOL(swap_page);
-
-/*
- * Page migration was first developed in the context of the memory hotplug
- * project. The main authors of the migration code are:
- *
- * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
- * Hirokazu Takahashi <taka@valinux.co.jp>
- * Dave Hansen <haveblue@us.ibm.com>
- * Christoph Lameter <clameter@sgi.com>
- */
-
-/*
- * Remove references for a page and establish the new page with the correct
- * basic settings to be able to stop accesses to the page.
- */
-int migrate_page_remove_references(struct page *newpage,
-				struct page *page, int nr_refs)
-{
-	struct address_space *mapping = page_mapping(page);
-	struct page **radix_pointer;
-
-	/*
-	 * Avoid doing any of the following work if the page count
-	 * indicates that the page is in use or truncate has removed
-	 * the page.
-	 */
-	if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
-		return 1;
-
-	/*
-	 * Establish swap ptes for anonymous pages or destroy pte
-	 * maps for files.
-	 *
-	 * In order to reestablish file backed mappings the fault handlers
-	 * will take the radix tree_lock which may then be used to stop
-  	 * processses from accessing this page until the new page is ready.
-	 *
-	 * A process accessing via a swap pte (an anonymous page) will take a
-	 * page_lock on the old page which will block the process until the
-	 * migration attempt is complete. At that time the PageSwapCache bit
-	 * will be examined. If the page was migrated then the PageSwapCache
-	 * bit will be clear and the operation to retrieve the page will be
-	 * retried which will find the new page in the radix tree. Then a new
-	 * direct mapping may be generated based on the radix tree contents.
-	 *
-	 * If the page was not migrated then the PageSwapCache bit
-	 * is still set and the operation may continue.
-	 */
-	try_to_unmap(page, 1);
-
-	/*
-	 * Give up if we were unable to remove all mappings.
-	 */
-	if (page_mapcount(page))
-		return 1;
-
-	write_lock_irq(&mapping->tree_lock);
-
-	radix_pointer = (struct page **)radix_tree_lookup_slot(
-						&mapping->page_tree,
-						page_index(page));
-
-	if (!page_mapping(page) || page_count(page) != nr_refs ||
-			*radix_pointer != page) {
-		write_unlock_irq(&mapping->tree_lock);
-		return 1;
-	}
-
-	/*
-	 * Now we know that no one else is looking at the page.
-	 *
-	 * Certain minimal information about a page must be available
-	 * in order for other subsystems to properly handle the page if they
-	 * find it through the radix tree update before we are finished
-	 * copying the page.
-	 */
-	get_page(newpage);
-	newpage->index = page->index;
-	newpage->mapping = page->mapping;
-	if (PageSwapCache(page)) {
-		SetPageSwapCache(newpage);
-		set_page_private(newpage, page_private(page));
-	}
-
-	*radix_pointer = newpage;
-	__put_page(page);
-	write_unlock_irq(&mapping->tree_lock);
-
-	return 0;
-}
-EXPORT_SYMBOL(migrate_page_remove_references);
-
-/*
- * Copy the page to its new location
- */
-void migrate_page_copy(struct page *newpage, struct page *page)
-{
-	copy_highpage(newpage, page);
-
-	if (PageError(page))
-		SetPageError(newpage);
-	if (PageReferenced(page))
-		SetPageReferenced(newpage);
-	if (PageUptodate(page))
-		SetPageUptodate(newpage);
-	if (PageActive(page))
-		SetPageActive(newpage);
-	if (PageChecked(page))
-		SetPageChecked(newpage);
-	if (PageMappedToDisk(page))
-		SetPageMappedToDisk(newpage);
-
-	if (PageDirty(page)) {
-		clear_page_dirty_for_io(page);
-		set_page_dirty(newpage);
- 	}
-
-	ClearPageSwapCache(page);
-	ClearPageActive(page);
-	ClearPagePrivate(page);
-	set_page_private(page, 0);
-	page->mapping = NULL;
-
-	/*
-	 * If any waiters have accumulated on the new page then
-	 * wake them up.
-	 */
-	if (PageWriteback(newpage))
-		end_page_writeback(newpage);
-}
-EXPORT_SYMBOL(migrate_page_copy);
-
-/*
- * Common logic to directly migrate a single page suitable for
- * pages that do not use PagePrivate.
- *
- * Pages are locked upon entry and exit.
- */
-int migrate_page(struct page *newpage, struct page *page)
-{
-	BUG_ON(PageWriteback(page));	/* Writeback must be complete */
-
-	if (migrate_page_remove_references(newpage, page, 2))
-		return -EAGAIN;
-
-	migrate_page_copy(newpage, page);
-
-	/*
-	 * Remove auxiliary swap entries and replace
-	 * them with real ptes.
-	 *
-	 * Note that a real pte entry will allow processes that are not
-	 * waiting on the page lock to use the new page via the page tables
-	 * before the new page is unlocked.
-	 */
-	remove_from_swap(newpage);
-	return 0;
-}
-EXPORT_SYMBOL(migrate_page);
-
-/*
- * migrate_pages
- *
- * Two lists are passed to this function. The first list
- * contains the pages isolated from the LRU to be migrated.
- * The second list contains new pages that the pages isolated
- * can be moved to. If the second list is NULL then all
- * pages are swapped out.
- *
- * The function returns after 10 attempts or if no pages
- * are movable anymore because to has become empty
- * or no retryable pages exist anymore.
- *
- * Return: Number of pages not migrated when "to" ran empty.
- */
-int migrate_pages(struct list_head *from, struct list_head *to,
-		  struct list_head *moved, struct list_head *failed)
-{
-	int retry;
-	int nr_failed = 0;
-	int pass = 0;
-	struct page *page;
-	struct page *page2;
-	int swapwrite = current->flags & PF_SWAPWRITE;
-	int rc;
-
-	if (!swapwrite)
-		current->flags |= PF_SWAPWRITE;
-
-redo:
-	retry = 0;
-
-	list_for_each_entry_safe(page, page2, from, lru) {
-		struct page *newpage = NULL;
-		struct address_space *mapping;
-
-		cond_resched();
-
-		rc = 0;
-		if (page_count(page) == 1)
-			/* page was freed from under us. So we are done. */
-			goto next;
-
-		if (to && list_empty(to))
-			break;
-
-		/*
-		 * Skip locked pages during the first two passes to give the
-		 * functions holding the lock time to release the page. Later we
-		 * use lock_page() to have a higher chance of acquiring the
-		 * lock.
-		 */
-		rc = -EAGAIN;
-		if (pass > 2)
-			lock_page(page);
-		else
-			if (TestSetPageLocked(page))
-				goto next;
-
-		/*
-		 * Only wait on writeback if we have already done a pass where
-		 * we we may have triggered writeouts for lots of pages.
-		 */
-		if (pass > 0) {
-			wait_on_page_writeback(page);
-		} else {
-			if (PageWriteback(page))
-				goto unlock_page;
-		}
-
-		/*
-		 * Anonymous pages must have swap cache references otherwise
-		 * the information contained in the page maps cannot be
-		 * preserved.
-		 */
-		if (PageAnon(page) && !PageSwapCache(page)) {
-			if (!add_to_swap(page, GFP_KERNEL)) {
-				rc = -ENOMEM;
-				goto unlock_page;
-			}
-		}
-
-		if (!to) {
-			rc = swap_page(page);
-			goto next;
-		}
-
-		newpage = lru_to_page(to);
-		lock_page(newpage);
-
-		/*
-		 * Pages are properly locked and writeback is complete.
-		 * Try to migrate the page.
-		 */
-		mapping = page_mapping(page);
-		if (!mapping)
-			goto unlock_both;
-
-		if (mapping->a_ops->migratepage) {
-			/*
-			 * Most pages have a mapping and most filesystems
-			 * should provide a migration function. Anonymous
-			 * pages are part of swap space which also has its
-			 * own migration function. This is the most common
-			 * path for page migration.
-			 */
-			rc = mapping->a_ops->migratepage(newpage, page);
-			goto unlock_both;
-                }
-
-		/*
-		 * Default handling if a filesystem does not provide
-		 * a migration function. We can only migrate clean
-		 * pages so try to write out any dirty pages first.
-		 */
-		if (PageDirty(page)) {
-			switch (pageout(page, mapping)) {
-			case PAGE_KEEP:
-			case PAGE_ACTIVATE:
-				goto unlock_both;
-
-			case PAGE_SUCCESS:
-				unlock_page(newpage);
-				goto next;
-
-			case PAGE_CLEAN:
-				; /* try to migrate the page below */
-			}
-                }
-
-		/*
-		 * Buffers are managed in a filesystem specific way.
-		 * We must have no buffers or drop them.
-		 */
-		if (!page_has_buffers(page) ||
-		    try_to_release_page(page, GFP_KERNEL)) {
-			rc = migrate_page(newpage, page);
-			goto unlock_both;
-		}
-
-		/*
-		 * On early passes with mapped pages simply
-		 * retry. There may be a lock held for some
-		 * buffers that may go away. Later
-		 * swap them out.
-		 */
-		if (pass > 4) {
-			/*
-			 * Persistently unable to drop buffers..... As a
-			 * measure of last resort we fall back to
-			 * swap_page().
-			 */
-			unlock_page(newpage);
-			newpage = NULL;
-			rc = swap_page(page);
-			goto next;
-		}
-
-unlock_both:
-		unlock_page(newpage);
-
-unlock_page:
-		unlock_page(page);
-
-next:
-		if (rc == -EAGAIN) {
-			retry++;
-		} else if (rc) {
-			/* Permanent failure */
-			list_move(&page->lru, failed);
-			nr_failed++;
-		} else {
-			if (newpage) {
-				/* Successful migration. Return page to LRU */
-				move_to_lru(newpage);
-			}
-			list_move(&page->lru, moved);
-		}
-	}
-	if (retry && pass++ < 10)
-		goto redo;
-
-	if (!swapwrite)
-		current->flags &= ~PF_SWAPWRITE;
-
-	return nr_failed + retry;
-}
-
-/*
- * Isolate one page from the LRU lists and put it on the
- * indicated list with elevated refcount.
- *
- * Result:
- *  0 = page not on LRU list
- *  1 = page removed from LRU list and added to the specified list.
- */
-int isolate_lru_page(struct page *page)
-{
-	int ret = 0;
-
-	if (PageLRU(page)) {
-		struct zone *zone = page_zone(page);
-		spin_lock_irq(&zone->lru_lock);
-		if (TestClearPageLRU(page)) {
-			ret = 1;
-			get_page(page);
-			if (PageActive(page))
-				del_page_from_active_list(zone, page);
-			else
-				del_page_from_inactive_list(zone, page);
-		}
-		spin_unlock_irq(&zone->lru_lock);
-	}
-
-	return ret;
-}
-#endif
-
 /*
  * zone->lru_lock is heavily contended.  Some of the functions that
  * shrink the lists perform better by taking out a batch of pages
Index: linux-2.6.16-rc6/include/linux/swap.h
===================================================================
--- linux-2.6.16-rc6.orig/include/linux/swap.h	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/include/linux/swap.h	2006-03-15 16:48:53.000000000 -0800
@@ -175,6 +175,21 @@ extern void swap_setup(void);
 extern int try_to_free_pages(struct zone **, gfp_t);
 extern int shrink_all_memory(int);
 extern int vm_swappiness;
+extern int remove_mapping(struct address_space *mapping, struct page *page);
+
+/* possible outcome of pageout() */
+typedef enum {
+	/* failed to write page out, page is locked */
+	PAGE_KEEP,
+	/* move page to the active list, page is locked */
+	PAGE_ACTIVATE,
+	/* page has been sent to the disk successfully, page is unlocked */
+	PAGE_SUCCESS,
+	/* page is clean and locked */
+	PAGE_CLEAN,
+} pageout_t;
+
+extern pageout_t pageout(struct page *page, struct address_space *mapping);
 
 #ifdef CONFIG_NUMA
 extern int zone_reclaim_mode;
@@ -188,25 +203,6 @@ static inline int zone_reclaim(struct zo
 }
 #endif
 
-#ifdef CONFIG_MIGRATION
-extern int isolate_lru_page(struct page *p);
-extern int putback_lru_pages(struct list_head *l);
-extern int migrate_page(struct page *, struct page *);
-extern void migrate_page_copy(struct page *, struct page *);
-extern int migrate_page_remove_references(struct page *, struct page *, int);
-extern int migrate_pages(struct list_head *l, struct list_head *t,
-		struct list_head *moved, struct list_head *failed);
-extern int fail_migrate_page(struct page *, struct page *);
-#else
-static inline int isolate_lru_page(struct page *p) { return -ENOSYS; }
-static inline int putback_lru_pages(struct list_head *l) { return 0; }
-static inline int migrate_pages(struct list_head *l, struct list_head *t,
-	struct list_head *moved, struct list_head *failed) { return -ENOSYS; }
-/* Possible settings for the migrate_page() method in address_operations */
-#define migrate_page NULL
-#define fail_migrate_page NULL
-#endif
-
 #ifdef CONFIG_MMU
 /* linux/mm/shmem.c */
 extern int shmem_unuse(swp_entry_t entry, struct page *page);
Index: linux-2.6.16-rc6/mm/mempolicy.c
===================================================================
--- linux-2.6.16-rc6.orig/mm/mempolicy.c	2006-03-14 19:52:25.000000000 -0800
+++ linux-2.6.16-rc6/mm/mempolicy.c	2006-03-15 17:33:31.000000000 -0800
@@ -86,6 +86,7 @@
 #include <linux/swap.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
+#include <linux/migrate.h>
 
 #include <asm/tlbflush.h>
 #include <asm/uaccess.h>
@@ -95,9 +96,6 @@
 #define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1)		/* Invert check for nodemask */
 #define MPOL_MF_STATS (MPOL_MF_INTERNAL << 2)		/* Gather statistics */
 
-/* The number of pages to migrate per call to migrate_pages() */
-#define MIGRATE_CHUNK_SIZE 256
-
 static kmem_cache_t *policy_cache;
 static kmem_cache_t *sn_cache;
 
@@ -331,6 +329,7 @@ check_range(struct mm_struct *mm, unsign
 	struct vm_area_struct *first, *vma, *prev;
 
 	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+#ifdef CONFIG_MIGRATION
 		/* Must have swap device for migration */
 		if (nr_swap_pages <= 0)
 			return ERR_PTR(-ENODEV);
@@ -342,6 +341,9 @@ check_range(struct mm_struct *mm, unsign
 		 * pages that may be busy.
 		 */
 		lru_add_drain_all();
+#else
+		return -ENOSYS;
+#endif
 	}
 
 	first = find_vma(mm, start);
@@ -553,10 +555,10 @@ long do_get_mempolicy(int *policy, nodem
 /*
  * page migration
  */
-
 static void migrate_page_add(struct page *page, struct list_head *pagelist,
 				unsigned long flags)
 {
+#ifdef CONFIG_MIGRATION
 	/*
 	 * Avoid migrating a page that is shared with others.
 	 */
@@ -564,80 +566,10 @@ static void migrate_page_add(struct page
 		if (isolate_lru_page(page))
 			list_add_tail(&page->lru, pagelist);
 	}
+#endif
 }
 
-/*
- * Migrate the list 'pagelist' of pages to a certain destination.
- *
- * Specify destination with either non-NULL vma or dest_node >= 0
- * Return the number of pages not migrated or error code
- */
-static int migrate_pages_to(struct list_head *pagelist,
-			struct vm_area_struct *vma, int dest)
-{
-	LIST_HEAD(newlist);
-	LIST_HEAD(moved);
-	LIST_HEAD(failed);
-	int err = 0;
-	unsigned long offset = 0;
-	int nr_pages;
-	struct page *page;
-	struct list_head *p;
-
-redo:
-	nr_pages = 0;
-	list_for_each(p, pagelist) {
-		if (vma) {
-			/*
-			 * The address passed to alloc_page_vma is used to
-			 * generate the proper interleave behavior. We fake
-			 * the address here by an increasing offset in order
-			 * to get the proper distribution of pages.
-			 *
-			 * No decision has been made as to which page
-			 * a certain old page is moved to so we cannot
-			 * specify the correct address.
-			 */
-			page = alloc_page_vma(GFP_HIGHUSER, vma,
-					offset + vma->vm_start);
-			offset += PAGE_SIZE;
-		}
-		else
-			page = alloc_pages_node(dest, GFP_HIGHUSER, 0);
-
-		if (!page) {
-			err = -ENOMEM;
-			goto out;
-		}
-		list_add_tail(&page->lru, &newlist);
-		nr_pages++;
-		if (nr_pages > MIGRATE_CHUNK_SIZE)
-			break;
-	}
-	err = migrate_pages(pagelist, &newlist, &moved, &failed);
-
-	putback_lru_pages(&moved);	/* Call release pages instead ?? */
-
-	if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist))
-		goto redo;
-out:
-	/* Return leftover allocated pages */
-	while (!list_empty(&newlist)) {
-		page = list_entry(newlist.next, struct page, lru);
-		list_del(&page->lru);
-		__free_page(page);
-	}
-	list_splice(&failed, pagelist);
-	if (err < 0)
-		return err;
-
-	/* Calculate number of leftover pages */
-	nr_pages = 0;
-	list_for_each(p, pagelist)
-		nr_pages++;
-	return nr_pages;
-}
-
+#ifdef CONFIG_MIGRATION
 /*
  * Migrate pages from one node to a target node.
  * Returns error or the number of pages not migrated.
@@ -661,6 +593,7 @@ int migrate_to_node(struct mm_struct *mm
 	}
 	return err;
 }
+#endif
 
 /*
  * Move pages between the two nodesets so as to preserve the physical
@@ -671,6 +604,7 @@ int migrate_to_node(struct mm_struct *mm
 int do_migrate_pages(struct mm_struct *mm,
 	const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags)
 {
+#ifdef CONFIG_MIGRATION
 	LIST_HEAD(pagelist);
 	int busy = 0;
 	int err = 0;
@@ -742,6 +676,9 @@ int do_migrate_pages(struct mm_struct *m
 	if (err < 0)
 		return err;
 	return busy;
+#else
+	return -ENOSYS;
+#endif
 }
 
 long do_mbind(unsigned long start, unsigned long len,
@@ -802,12 +739,15 @@ long do_mbind(unsigned long start, unsig
 
 		err = mbind_range(vma, start, end, new);
 
+#ifdef CONFIG_MIGRATION
 		if (!list_empty(&pagelist))
 			nr_failed = migrate_pages_to(&pagelist, vma, -1);
+#endif
 
 		if (!err && nr_failed && (flags & MPOL_MF_STRICT))
 			err = -EIO;
 	}
+
 	if (!list_empty(&pagelist))
 		putback_lru_pages(&pagelist);
 
Index: linux-2.6.16-rc6/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- linux-2.6.16-rc6.orig/fs/xfs/linux-2.6/xfs_buf.c	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/fs/xfs/linux-2.6/xfs_buf.c	2006-03-15 17:03:01.000000000 -0800
@@ -29,6 +29,7 @@
 #include <linux/blkdev.h>
 #include <linux/hash.h>
 #include <linux/kthread.h>
+#include <linux/migrate.h>
 #include "xfs_linux.h"
 
 STATIC kmem_zone_t *xfs_buf_zone;
Index: linux-2.6.16-rc6/fs/buffer.c
===================================================================
--- linux-2.6.16-rc6.orig/fs/buffer.c	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/fs/buffer.c	2006-03-15 17:09:57.000000000 -0800
@@ -3051,66 +3051,6 @@ asmlinkage long sys_bdflush(int func, lo
 }
 
 /*
- * Migration function for pages with buffers. This function can only be used
- * if the underlying filesystem guarantees that no other references to "page"
- * exist.
- */
-#ifdef CONFIG_MIGRATION
-int buffer_migrate_page(struct page *newpage, struct page *page)
-{
-	struct address_space *mapping = page->mapping;
-	struct buffer_head *bh, *head;
-
-	if (!mapping)
-		return -EAGAIN;
-
-	if (!page_has_buffers(page))
-		return migrate_page(newpage, page);
-
-	head = page_buffers(page);
-
-	if (migrate_page_remove_references(newpage, page, 3))
-		return -EAGAIN;
-
-	bh = head;
-	do {
-		get_bh(bh);
-		lock_buffer(bh);
-		bh = bh->b_this_page;
-
-	} while (bh != head);
-
-	ClearPagePrivate(page);
-	set_page_private(newpage, page_private(page));
-	set_page_private(page, 0);
-	put_page(page);
-	get_page(newpage);
-
-	bh = head;
-	do {
-		set_bh_page(bh, newpage, bh_offset(bh));
-		bh = bh->b_this_page;
-
-	} while (bh != head);
-
-	SetPagePrivate(newpage);
-
-	migrate_page_copy(newpage, page);
-
-	bh = head;
-	do {
-		unlock_buffer(bh);
- 		put_bh(bh);
-		bh = bh->b_this_page;
-
-	} while (bh != head);
-
-	return 0;
-}
-EXPORT_SYMBOL(buffer_migrate_page);
-#endif
-
-/*
  * Buffer-head allocation
  */
 static kmem_cache_t *bh_cachep;
Index: linux-2.6.16-rc6/mm/Kconfig
===================================================================
--- linux-2.6.16-rc6.orig/mm/Kconfig	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/mm/Kconfig	2006-03-15 17:31:53.000000000 -0800
@@ -137,5 +137,11 @@ config SPLIT_PTLOCK_CPUS
 # support for page migration
 #
 config MIGRATION
+	bool "Page migration"
 	def_bool y if NUMA || SPARSEMEM || DISCONTIGMEM
 	depends on SWAP
+	help
+	  Allows the migration of the physical location of pages of processes
+	  while the virtual addresses are not changed. This is useful for
+	  example on NUMA systems to put pages nearer to the processors accessing
+	  the page.

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Re: page migration reorg patch

[Christoph Lameter]

Missing migrate.h:

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.16-rc6/include/linux/migrate.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.16-rc6/include/linux/migrate.h	2006-03-15 17:46:12.000000000 -0800
@@ -0,0 +1,31 @@
+#ifndef _LINUX_MIGRATE_H
+#define _LINUX_MIGRATE_H
+
+#include <linux/config.h>
+#include <linux/mm.h>
+
+#ifdef CONFIG_MIGRATION
+extern int isolate_lru_page(struct page *p);
+extern int putback_lru_pages(struct list_head *l);
+extern int migrate_page(struct page *, struct page *);
+extern void migrate_page_copy(struct page *, struct page *);
+extern int migrate_page_remove_references(struct page *, struct page *, int);
+extern int migrate_pages(struct list_head *l, struct list_head *t,
+		struct list_head *moved, struct list_head *failed);
+int migrate_pages_to(struct list_head *pagelist,
+			struct vm_area_struct *vma, int dest);
+extern int fail_migrate_page(struct page *, struct page *);
+
+#else
+
+static inline int isolate_lru_page(struct page *p) { return -ENOSYS; }
+static inline int putback_lru_pages(struct list_head *l) { return 0; }
+static inline int migrate_pages(struct list_head *l, struct list_head *t,
+	struct list_head *moved, struct list_head *failed) { return -ENOSYS; }
+
+/* Possible settings for the migrate_page() method in address_operations */
+#define migrate_page NULL
+#define fail_migrate_page NULL
+
+#endif /* CONFIG_MIGRATION */
+#endif /* _LINUX_MIGRATE_H */

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Re: page migration reorg patch

[Andrew Morton]

Christoph Lameter <clameter@sgi.com> wrote:
>
> This patch centralizes the page migration functions in anticipation of 
>  additional tinkering.

That was a bit optimistic :(

bix:/usr/src/25> wc mm/vmscan.c.rej include/linux/swap.h.rej mm/mempolicy.c.rej fs/buffer.c.rej    
    483    2046   12204 mm/vmscan.c.rej
     34     170    1268 include/linux/swap.h.rej
     18      77     613 mm/mempolicy.c.rej
     75     212    1456 fs/buffer.c.rej
    610    2505   15541 total

Am currently sitting on 136 patches which touch mm/*.

If you can rework this patch against
http://www.zip.com.au/~akpm/linux/patches/stuff/x.bz2 (my current queue up
to and including slab-leaks3-locking-fix.patch, against 2.6.16-rc6) then
I'll be able to insert it in the right place and then fix up subsequent
fallout, thanks.


Or we can just do it later.  Whenever that is.

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Re: page migration reorg patch

[Christoph Lameter]

Gosh. Why am I not perfect. Bonk bonk....

Missing include in swap_state.c

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.16-rc6/mm/swap_state.c
===================================================================
--- linux-2.6.16-rc6.orig/mm/swap_state.c	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/mm/swap_state.c	2006-03-15 17:53:19.000000000 -0800
@@ -15,6 +15,7 @@
 #include <linux/buffer_head.h>
 #include <linux/backing-dev.h>
 #include <linux/pagevec.h>
+#include <linux/migrate.h>
 
 #include <asm/pgtable.h>
 

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Re: page migration reorg patch

[Christoph Lameter]

On Wed, 15 Mar 2006, Andrew Morton wrote:

> If you can rework this patch against
> http://www.zip.com.au/~akpm/linux/patches/stuff/x.bz2 (my current queue up
> to and including slab-leaks3-locking-fix.patch, against 2.6.16-rc6) then
> I'll be able to insert it in the right place and then fix up subsequent
> fallout, thanks.

BTW compilation fails with:

drivers/scsi/sata_vsc.c: At top level:
drivers/scsi/sata_vsc.c:254: unknown field `eh_timed_out' specified in 
initializer
drivers/scsi/sata_vsc.c:254: warning: initialization from incompatible 
pointer type


The patch (including the two amendments) against the x.bz2 patch:



This patch centralizes the page migration functions in anticipation of
additional tinkering. Creates a new file mm/migrate.c

1. Extract buffer_migrate_page() from fs/buffer.c

2. Extract central migration code from vmscan.c

3. Extract some components from mempolicy.c

4. Export pageout() and remove_from_swap() from vmscan.c

5. Make it possible to configure NUMA systems without page migration
   and non-NUMA systems with page migration.

I had to so some #ifdeffing in mempolicy.c that may need a cleanup.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.16-rc6/mm/Makefile
===================================================================
--- linux-2.6.16-rc6.orig/mm/Makefile	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/mm/Makefile	2006-03-15 18:15:42.000000000 -0800
@@ -22,3 +22,5 @@ obj-$(CONFIG_SLOB) += slob.o
 obj-$(CONFIG_SLAB) += slab.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
 obj-$(CONFIG_FS_XIP) += filemap_xip.o
+obj-$(CONFIG_MIGRATION) += migrate.o
+
Index: linux-2.6.16-rc6/mm/migrate.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.16-rc6/mm/migrate.c	2006-03-15 18:26:12.000000000 -0800
@@ -0,0 +1,629 @@
+/*
+ * Memory Migration functionality - linux/mm/migration.c
+ *
+ * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
+ *
+ * Page migration was first developed in the context of the memory hotplug
+ * project. The main authors of the migration code are:
+ *
+ * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
+ * Hirokazu Takahashi <taka@valinux.co.jp>
+ * Dave Hansen <haveblue@us.ibm.com>
+ * Christoph Lameter <clameter@sgi.com>
+ */
+
+#include <linux/migrate.h>
+#include <linux/module.h>
+#include <linux/swap.h>
+#include <linux/pagemap.h>
+#include <linux/buffer_head.h>	/* for try_to_release_page(),
+					buffer_heads_over_limit */
+#include <linux/mm_inline.h>
+#include <linux/pagevec.h>
+#include <linux/rmap.h>
+#include <linux/topology.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/swapops.h>
+
+/* The maximum number of pages to take off the LRU for migration */
+#define MIGRATE_CHUNK_SIZE 256
+
+#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
+
+static inline void move_to_lru(struct page *page)
+{
+	list_del(&page->lru);
+	if (PageActive(page)) {
+		/*
+		 * lru_cache_add_active checks that
+		 * the PG_active bit is off.
+		 */
+		ClearPageActive(page);
+		lru_cache_add_active(page);
+	} else {
+		lru_cache_add(page);
+	}
+	put_page(page);
+}
+
+/*
+ * Add isolated pages on the list back to the LRU.
+ *
+ * returns the number of pages put back.
+ */
+int putback_lru_pages(struct list_head *l)
+{
+	struct page *page;
+	struct page *page2;
+	int count = 0;
+
+	list_for_each_entry_safe(page, page2, l, lru) {
+		move_to_lru(page);
+		count++;
+	}
+	return count;
+}
+
+/*
+ * Non migratable page
+ */
+int fail_migrate_page(struct page *newpage, struct page *page)
+{
+	return -EIO;
+}
+EXPORT_SYMBOL(fail_migrate_page);
+
+/*
+ * swapout a single page
+ * page is locked upon entry, unlocked on exit
+ */
+static int swap_page(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+
+	if (page_mapped(page) && mapping)
+		if (try_to_unmap(page, 1) != SWAP_SUCCESS)
+			goto unlock_retry;
+
+	if (PageDirty(page)) {
+		/* Page is dirty, try to write it out here */
+		switch(pageout(page, mapping)) {
+		case PAGE_KEEP:
+		case PAGE_ACTIVATE:
+			goto unlock_retry;
+
+		case PAGE_SUCCESS:
+			goto retry;
+
+		case PAGE_CLEAN:
+			; /* try to free the page below */
+		}
+	}
+
+	if (PagePrivate(page)) {
+		if (!try_to_release_page(page, GFP_KERNEL) ||
+		    (!mapping && page_count(page) == 1))
+			goto unlock_retry;
+	}
+
+	if (remove_mapping(mapping, page)) {
+		/* Success */
+		unlock_page(page);
+		return 0;
+	}
+
+unlock_retry:
+	unlock_page(page);
+
+retry:
+	return -EAGAIN;
+}
+EXPORT_SYMBOL(swap_page);
+
+/*
+ * Remove references for a page and establish the new page with the correct
+ * basic settings to be able to stop accesses to the page.
+ */
+int migrate_page_remove_references(struct page *newpage,
+				struct page *page, int nr_refs)
+{
+	struct address_space *mapping = page_mapping(page);
+	struct page **radix_pointer;
+
+	/*
+	 * Avoid doing any of the following work if the page count
+	 * indicates that the page is in use or truncate has removed
+	 * the page.
+	 */
+	if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
+		return -EAGAIN;
+
+	/*
+	 * Establish swap ptes for anonymous pages or destroy pte
+	 * maps for files.
+	 *
+	 * In order to reestablish file backed mappings the fault handlers
+	 * will take the radix tree_lock which may then be used to stop
+  	 * processses from accessing this page until the new page is ready.
+	 *
+	 * A process accessing via a swap pte (an anonymous page) will take a
+	 * page_lock on the old page which will block the process until the
+	 * migration attempt is complete. At that time the PageSwapCache bit
+	 * will be examined. If the page was migrated then the PageSwapCache
+	 * bit will be clear and the operation to retrieve the page will be
+	 * retried which will find the new page in the radix tree. Then a new
+	 * direct mapping may be generated based on the radix tree contents.
+	 *
+	 * If the page was not migrated then the PageSwapCache bit
+	 * is still set and the operation may continue.
+	 */
+	if (try_to_unmap(page, 1) == SWAP_FAIL)
+		/* A vma has VM_LOCKED set -> permanent failure */
+		return -EPERM;
+
+	/*
+	 * Give up if we were unable to remove all mappings.
+	 */
+	if (page_mapcount(page))
+		return -EAGAIN;
+
+	write_lock_irq(&mapping->tree_lock);
+
+	radix_pointer = (struct page **)radix_tree_lookup_slot(
+						&mapping->page_tree,
+						page_index(page));
+
+	if (!page_mapping(page) || page_count(page) != nr_refs ||
+			*radix_pointer != page) {
+		write_unlock_irq(&mapping->tree_lock);
+		return 1;
+	}
+
+	/*
+	 * Now we know that no one else is looking at the page.
+	 *
+	 * Certain minimal information about a page must be available
+	 * in order for other subsystems to properly handle the page if they
+	 * find it through the radix tree update before we are finished
+	 * copying the page.
+	 */
+	get_page(newpage);
+	newpage->index = page->index;
+	newpage->mapping = page->mapping;
+	if (PageSwapCache(page)) {
+		SetPageSwapCache(newpage);
+		set_page_private(newpage, page_private(page));
+	}
+
+	*radix_pointer = newpage;
+	__put_page(page);
+	write_unlock_irq(&mapping->tree_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(migrate_page_remove_references);
+
+/*
+ * Copy the page to its new location
+ */
+void migrate_page_copy(struct page *newpage, struct page *page)
+{
+	copy_highpage(newpage, page);
+
+	if (PageError(page))
+		SetPageError(newpage);
+	if (PageReferenced(page))
+		SetPageReferenced(newpage);
+	if (PageUptodate(page))
+		SetPageUptodate(newpage);
+	if (PageActive(page))
+		SetPageActive(newpage);
+	if (PageChecked(page))
+		SetPageChecked(newpage);
+	if (PageMappedToDisk(page))
+		SetPageMappedToDisk(newpage);
+
+	if (PageDirty(page)) {
+		clear_page_dirty_for_io(page);
+		set_page_dirty(newpage);
+ 	}
+
+	ClearPageSwapCache(page);
+	ClearPageActive(page);
+	ClearPagePrivate(page);
+	set_page_private(page, 0);
+	page->mapping = NULL;
+
+	/*
+	 * If any waiters have accumulated on the new page then
+	 * wake them up.
+	 */
+	if (PageWriteback(newpage))
+		end_page_writeback(newpage);
+}
+EXPORT_SYMBOL(migrate_page_copy);
+
+/*
+ * Common logic to directly migrate a single page suitable for
+ * pages that do not use PagePrivate.
+ *
+ * Pages are locked upon entry and exit.
+ */
+int migrate_page(struct page *newpage, struct page *page)
+{
+	int rc;
+
+	BUG_ON(PageWriteback(page));	/* Writeback must be complete */
+
+	rc = migrate_page_remove_references(newpage, page, 2);
+
+	if (rc)
+		return rc;
+
+	migrate_page_copy(newpage, page);
+
+	/*
+	 * Remove auxiliary swap entries and replace
+	 * them with real ptes.
+	 *
+	 * Note that a real pte entry will allow processes that are not
+	 * waiting on the page lock to use the new page via the page tables
+	 * before the new page is unlocked.
+	 */
+	remove_from_swap(newpage);
+	return 0;
+}
+EXPORT_SYMBOL(migrate_page);
+
+/*
+ * migrate_pages
+ *
+ * Two lists are passed to this function. The first list
+ * contains the pages isolated from the LRU to be migrated.
+ * The second list contains new pages that the pages isolated
+ * can be moved to. If the second list is NULL then all
+ * pages are swapped out.
+ *
+ * The function returns after 10 attempts or if no pages
+ * are movable anymore because to has become empty
+ * or no retryable pages exist anymore.
+ *
+ * Return: Number of pages not migrated when "to" ran empty.
+ */
+int migrate_pages(struct list_head *from, struct list_head *to,
+		  struct list_head *moved, struct list_head *failed)
+{
+	int retry;
+	int nr_failed = 0;
+	int pass = 0;
+	struct page *page;
+	struct page *page2;
+	int swapwrite = current->flags & PF_SWAPWRITE;
+	int rc;
+
+	if (!swapwrite)
+		current->flags |= PF_SWAPWRITE;
+
+redo:
+	retry = 0;
+
+	list_for_each_entry_safe(page, page2, from, lru) {
+		struct page *newpage = NULL;
+		struct address_space *mapping;
+
+		cond_resched();
+
+		rc = 0;
+		if (page_count(page) == 1)
+			/* page was freed from under us. So we are done. */
+			goto next;
+
+		if (to && list_empty(to))
+			break;
+
+		/*
+		 * Skip locked pages during the first two passes to give the
+		 * functions holding the lock time to release the page. Later we
+		 * use lock_page() to have a higher chance of acquiring the
+		 * lock.
+		 */
+		rc = -EAGAIN;
+		if (pass > 2)
+			lock_page(page);
+		else
+			if (TestSetPageLocked(page))
+				goto next;
+
+		/*
+		 * Only wait on writeback if we have already done a pass where
+		 * we we may have triggered writeouts for lots of pages.
+		 */
+		if (pass > 0) {
+			wait_on_page_writeback(page);
+		} else {
+			if (PageWriteback(page))
+				goto unlock_page;
+		}
+
+		/*
+		 * Anonymous pages must have swap cache references otherwise
+		 * the information contained in the page maps cannot be
+		 * preserved.
+		 */
+		if (PageAnon(page) && !PageSwapCache(page)) {
+			if (!add_to_swap(page, GFP_KERNEL)) {
+				rc = -ENOMEM;
+				goto unlock_page;
+			}
+		}
+
+		if (!to) {
+			rc = swap_page(page);
+			goto next;
+		}
+
+		newpage = lru_to_page(to);
+		lock_page(newpage);
+
+		/*
+		 * Pages are properly locked and writeback is complete.
+		 * Try to migrate the page.
+		 */
+		mapping = page_mapping(page);
+		if (!mapping)
+			goto unlock_both;
+
+		if (mapping->a_ops->migratepage) {
+			/*
+			 * Most pages have a mapping and most filesystems
+			 * should provide a migration function. Anonymous
+			 * pages are part of swap space which also has its
+			 * own migration function. This is the most common
+			 * path for page migration.
+			 */
+			rc = mapping->a_ops->migratepage(newpage, page);
+			goto unlock_both;
+                }
+
+		/*
+		 * Default handling if a filesystem does not provide
+		 * a migration function. We can only migrate clean
+		 * pages so try to write out any dirty pages first.
+		 */
+		if (PageDirty(page)) {
+			switch (pageout(page, mapping)) {
+			case PAGE_KEEP:
+			case PAGE_ACTIVATE:
+				goto unlock_both;
+
+			case PAGE_SUCCESS:
+				unlock_page(newpage);
+				goto next;
+
+			case PAGE_CLEAN:
+				; /* try to migrate the page below */
+			}
+                }
+
+		/*
+		 * Buffers are managed in a filesystem specific way.
+		 * We must have no buffers or drop them.
+		 */
+		if (!page_has_buffers(page) ||
+		    try_to_release_page(page, GFP_KERNEL)) {
+			rc = migrate_page(newpage, page);
+			goto unlock_both;
+		}
+
+		/*
+		 * On early passes with mapped pages simply
+		 * retry. There may be a lock held for some
+		 * buffers that may go away. Later
+		 * swap them out.
+		 */
+		if (pass > 4) {
+			/*
+			 * Persistently unable to drop buffers..... As a
+			 * measure of last resort we fall back to
+			 * swap_page().
+			 */
+			unlock_page(newpage);
+			newpage = NULL;
+			rc = swap_page(page);
+			goto next;
+		}
+
+unlock_both:
+		unlock_page(newpage);
+
+unlock_page:
+		unlock_page(page);
+
+next:
+		if (rc == -EAGAIN) {
+			retry++;
+		} else if (rc) {
+			/* Permanent failure */
+			list_move(&page->lru, failed);
+			nr_failed++;
+		} else {
+			if (newpage) {
+				/* Successful migration. Return page to LRU */
+				move_to_lru(newpage);
+			}
+			list_move(&page->lru, moved);
+		}
+	}
+	if (retry && pass++ < 10)
+		goto redo;
+
+	if (!swapwrite)
+		current->flags &= ~PF_SWAPWRITE;
+
+	return nr_failed + retry;
+}
+
+/*
+ * Isolate one page from the LRU lists and put it on the
+ * indicated list with elevated refcount.
+ *
+ * Result:
+ *  0 = page not on LRU list
+ *  1 = page removed from LRU list and added to the specified list.
+ */
+int isolate_lru_page(struct page *page)
+{
+	int ret = 0;
+
+	if (PageLRU(page)) {
+		struct zone *zone = page_zone(page);
+		spin_lock_irq(&zone->lru_lock);
+		if (TestClearPageLRU(page)) {
+			ret = 1;
+			get_page(page);
+			if (PageActive(page))
+				del_page_from_active_list(zone, page);
+			else
+				del_page_from_inactive_list(zone, page);
+		}
+		spin_unlock_irq(&zone->lru_lock);
+	}
+
+	return ret;
+}
+
+/*
+ * Migration function for pages with buffers. This function can only be used
+ * if the underlying filesystem guarantees that no other references to "page"
+ * exist.
+ */
+int buffer_migrate_page(struct page *newpage, struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct buffer_head *bh, *head;
+	int rc;
+
+	if (!mapping)
+		return -EAGAIN;
+
+	if (!page_has_buffers(page))
+		return migrate_page(newpage, page);
+
+	head = page_buffers(page);
+
+	rc = migrate_page_remove_references(newpage, page, 3);
+
+	if (rc)
+		return rc;
+
+	bh = head;
+	do {
+		get_bh(bh);
+		lock_buffer(bh);
+		bh = bh->b_this_page;
+
+	} while (bh != head);
+
+	ClearPagePrivate(page);
+	set_page_private(newpage, page_private(page));
+	set_page_private(page, 0);
+	put_page(page);
+	get_page(newpage);
+
+	bh = head;
+	do {
+		set_bh_page(bh, newpage, bh_offset(bh));
+		bh = bh->b_this_page;
+
+	} while (bh != head);
+
+	SetPagePrivate(newpage);
+
+	migrate_page_copy(newpage, page);
+
+	bh = head;
+	do {
+		unlock_buffer(bh);
+ 		put_bh(bh);
+		bh = bh->b_this_page;
+
+	} while (bh != head);
+
+	return 0;
+}
+EXPORT_SYMBOL(buffer_migrate_page);
+
+#ifdef CONFIG_NUMA
+/*
+ * Migrate the list 'pagelist' of pages to a certain destination.
+ *
+ * Specify destination with either non-NULL vma or dest_node >= 0
+ * Return the number of pages not migrated or error code
+ */
+int migrate_pages_to(struct list_head *pagelist,
+			struct vm_area_struct *vma, int dest)
+{
+	LIST_HEAD(newlist);
+	LIST_HEAD(moved);
+	LIST_HEAD(failed);
+	int err = 0;
+	unsigned long offset = 0;
+	int nr_pages;
+	struct page *page;
+	struct list_head *p;
+
+redo:
+	nr_pages = 0;
+	list_for_each(p, pagelist) {
+		if (vma) {
+			/*
+			 * The address passed to alloc_page_vma is used to
+			 * generate the proper interleave behavior. We fake
+			 * the address here by an increasing offset in order
+			 * to get the proper distribution of pages.
+			 *
+			 * No decision has been made as to which page
+			 * a certain old page is moved to so we cannot
+			 * specify the correct address.
+			 */
+			page = alloc_page_vma(GFP_HIGHUSER, vma,
+					offset + vma->vm_start);
+			offset += PAGE_SIZE;
+		}
+		else
+			page = alloc_pages_node(dest, GFP_HIGHUSER, 0);
+
+		if (!page) {
+			err = -ENOMEM;
+			goto out;
+		}
+		list_add_tail(&page->lru, &newlist);
+		nr_pages++;
+		if (nr_pages > MIGRATE_CHUNK_SIZE)
+			break;
+	}
+	err = migrate_pages(pagelist, &newlist, &moved, &failed);
+
+	putback_lru_pages(&moved);	/* Call release pages instead ?? */
+
+	if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist))
+		goto redo;
+out:
+	/* Return leftover allocated pages */
+	while (!list_empty(&newlist)) {
+		page = list_entry(newlist.next, struct page, lru);
+		list_del(&page->lru);
+		__free_page(page);
+	}
+	list_splice(&failed, pagelist);
+	if (err < 0)
+		return err;
+
+	/* Calculate number of leftover pages */
+	nr_pages = 0;
+	list_for_each(p, pagelist)
+		nr_pages++;
+	return nr_pages;
+}
+#endif
Index: linux-2.6.16-rc6/mm/vmscan.c
===================================================================
--- linux-2.6.16-rc6.orig/mm/vmscan.c	2006-03-15 18:15:14.000000000 -0800
+++ linux-2.6.16-rc6/mm/vmscan.c	2006-03-15 18:21:24.000000000 -0800
@@ -42,18 +42,6 @@
 
 #include "internal.h"
 
-/* possible outcome of pageout() */
-typedef enum {
-	/* failed to write page out, page is locked */
-	PAGE_KEEP,
-	/* move page to the active list, page is locked */
-	PAGE_ACTIVATE,
-	/* page has been sent to the disk successfully, page is unlocked */
-	PAGE_SUCCESS,
-	/* page is clean and locked */
-	PAGE_CLEAN,
-} pageout_t;
-
 struct scan_control {
 	/* Incremented by the number of inactive pages that were scanned */
 	unsigned long nr_scanned;
@@ -304,7 +292,7 @@ static void handle_write_error(struct ad
  * pageout is called by shrink_page_list() for each dirty page.
  * Calls ->writepage().
  */
-static pageout_t pageout(struct page *page, struct address_space *mapping)
+pageout_t pageout(struct page *page, struct address_space *mapping)
 {
 	/*
 	 * If the page is dirty, only perform writeback if that write
@@ -372,7 +360,7 @@ static pageout_t pageout(struct page *pa
 	return PAGE_CLEAN;
 }
 
-static int remove_mapping(struct address_space *mapping, struct page *page)
+int remove_mapping(struct address_space *mapping, struct page *page)
 {
 	if (!mapping)
 		return 0;		/* truncate got there first */
@@ -570,481 +558,6 @@ keep:
 	return nr_reclaimed;
 }
 
-#ifdef CONFIG_MIGRATION
-static inline void move_to_lru(struct page *page)
-{
-	list_del(&page->lru);
-	if (PageActive(page)) {
-		/*
-		 * lru_cache_add_active checks that
-		 * the PG_active bit is off.
-		 */
-		ClearPageActive(page);
-		lru_cache_add_active(page);
-	} else {
-		lru_cache_add(page);
-	}
-	put_page(page);
-}
-
-/*
- * Add isolated pages on the list back to the LRU.
- *
- * returns the number of pages put back.
- */
-unsigned long putback_lru_pages(struct list_head *l)
-{
-	struct page *page;
-	struct page *page2;
-	unsigned long count = 0;
-
-	list_for_each_entry_safe(page, page2, l, lru) {
-		move_to_lru(page);
-		count++;
-	}
-	return count;
-}
-
-/*
- * Non migratable page
- */
-int fail_migrate_page(struct page *newpage, struct page *page)
-{
-	return -EIO;
-}
-EXPORT_SYMBOL(fail_migrate_page);
-
-/*
- * swapout a single page
- * page is locked upon entry, unlocked on exit
- */
-static int swap_page(struct page *page)
-{
-	struct address_space *mapping = page_mapping(page);
-
-	if (page_mapped(page) && mapping)
-		if (try_to_unmap(page, 1) != SWAP_SUCCESS)
-			goto unlock_retry;
-
-	if (PageDirty(page)) {
-		/* Page is dirty, try to write it out here */
-		switch(pageout(page, mapping)) {
-		case PAGE_KEEP:
-		case PAGE_ACTIVATE:
-			goto unlock_retry;
-
-		case PAGE_SUCCESS:
-			goto retry;
-
-		case PAGE_CLEAN:
-			; /* try to free the page below */
-		}
-	}
-
-	if (PagePrivate(page)) {
-		if (!try_to_release_page(page, GFP_KERNEL) ||
-		    (!mapping && page_count(page) == 1))
-			goto unlock_retry;
-	}
-
-	if (remove_mapping(mapping, page)) {
-		/* Success */
-		unlock_page(page);
-		return 0;
-	}
-
-unlock_retry:
-	unlock_page(page);
-
-retry:
-	return -EAGAIN;
-}
-EXPORT_SYMBOL(swap_page);
-
-/*
- * Page migration was first developed in the context of the memory hotplug
- * project. The main authors of the migration code are:
- *
- * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
- * Hirokazu Takahashi <taka@valinux.co.jp>
- * Dave Hansen <haveblue@us.ibm.com>
- * Christoph Lameter <clameter@sgi.com>
- */
-
-/*
- * Remove references for a page and establish the new page with the correct
- * basic settings to be able to stop accesses to the page.
- */
-int migrate_page_remove_references(struct page *newpage,
-				struct page *page, int nr_refs)
-{
-	struct address_space *mapping = page_mapping(page);
-	struct page **radix_pointer;
-
-	/*
-	 * Avoid doing any of the following work if the page count
-	 * indicates that the page is in use or truncate has removed
-	 * the page.
-	 */
-	if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
-		return -EAGAIN;
-
-	/*
-	 * Establish swap ptes for anonymous pages or destroy pte
-	 * maps for files.
-	 *
-	 * In order to reestablish file backed mappings the fault handlers
-	 * will take the radix tree_lock which may then be used to stop
-  	 * processses from accessing this page until the new page is ready.
-	 *
-	 * A process accessing via a swap pte (an anonymous page) will take a
-	 * page_lock on the old page which will block the process until the
-	 * migration attempt is complete. At that time the PageSwapCache bit
-	 * will be examined. If the page was migrated then the PageSwapCache
-	 * bit will be clear and the operation to retrieve the page will be
-	 * retried which will find the new page in the radix tree. Then a new
-	 * direct mapping may be generated based on the radix tree contents.
-	 *
-	 * If the page was not migrated then the PageSwapCache bit
-	 * is still set and the operation may continue.
-	 */
-	if (try_to_unmap(page, 1) == SWAP_FAIL)
-		/* A vma has VM_LOCKED set -> Permanent failure */
-		return -EPERM;
-
-	/*
-	 * Give up if we were unable to remove all mappings.
-	 */
-	if (page_mapcount(page))
-		return -EAGAIN;
-
-	write_lock_irq(&mapping->tree_lock);
-
-	radix_pointer = (struct page **)radix_tree_lookup_slot(
-						&mapping->page_tree,
-						page_index(page));
-
-	if (!page_mapping(page) || page_count(page) != nr_refs ||
-			*radix_pointer != page) {
-		write_unlock_irq(&mapping->tree_lock);
-		return -EAGAIN;
-	}
-
-	/*
-	 * Now we know that no one else is looking at the page.
-	 *
-	 * Certain minimal information about a page must be available
-	 * in order for other subsystems to properly handle the page if they
-	 * find it through the radix tree update before we are finished
-	 * copying the page.
-	 */
-	get_page(newpage);
-	newpage->index = page->index;
-	newpage->mapping = page->mapping;
-	if (PageSwapCache(page)) {
-		SetPageSwapCache(newpage);
-		set_page_private(newpage, page_private(page));
-	}
-
-	*radix_pointer = newpage;
-	__put_page(page);
-	write_unlock_irq(&mapping->tree_lock);
-
-	return 0;
-}
-EXPORT_SYMBOL(migrate_page_remove_references);
-
-/*
- * Copy the page to its new location
- */
-void migrate_page_copy(struct page *newpage, struct page *page)
-{
-	copy_highpage(newpage, page);
-
-	if (PageError(page))
-		SetPageError(newpage);
-	if (PageReferenced(page))
-		SetPageReferenced(newpage);
-	if (PageUptodate(page))
-		SetPageUptodate(newpage);
-	if (PageActive(page))
-		SetPageActive(newpage);
-	if (PageChecked(page))
-		SetPageChecked(newpage);
-	if (PageMappedToDisk(page))
-		SetPageMappedToDisk(newpage);
-
-	if (PageDirty(page)) {
-		clear_page_dirty_for_io(page);
-		set_page_dirty(newpage);
- 	}
-
-	ClearPageSwapCache(page);
-	ClearPageActive(page);
-	ClearPagePrivate(page);
-	set_page_private(page, 0);
-	page->mapping = NULL;
-
-	/*
-	 * If any waiters have accumulated on the new page then
-	 * wake them up.
-	 */
-	if (PageWriteback(newpage))
-		end_page_writeback(newpage);
-}
-EXPORT_SYMBOL(migrate_page_copy);
-
-/*
- * Common logic to directly migrate a single page suitable for
- * pages that do not use PagePrivate.
- *
- * Pages are locked upon entry and exit.
- */
-int migrate_page(struct page *newpage, struct page *page)
-{
-	int rc;
-
-	BUG_ON(PageWriteback(page));	/* Writeback must be complete */
-
-	rc = migrate_page_remove_references(newpage, page, 2);
-
-	if (rc)
-		return rc;
-
-	migrate_page_copy(newpage, page);
-
-	/*
-	 * Remove auxiliary swap entries and replace
-	 * them with real ptes.
-	 *
-	 * Note that a real pte entry will allow processes that are not
-	 * waiting on the page lock to use the new page via the page tables
-	 * before the new page is unlocked.
-	 */
-	remove_from_swap(newpage);
-	return 0;
-}
-EXPORT_SYMBOL(migrate_page);
-
-/*
- * migrate_pages
- *
- * Two lists are passed to this function. The first list
- * contains the pages isolated from the LRU to be migrated.
- * The second list contains new pages that the pages isolated
- * can be moved to. If the second list is NULL then all
- * pages are swapped out.
- *
- * The function returns after 10 attempts or if no pages
- * are movable anymore because to has become empty
- * or no retryable pages exist anymore.
- *
- * Return: Number of pages not migrated when "to" ran empty.
- */
-unsigned long migrate_pages(struct list_head *from, struct list_head *to,
-		  struct list_head *moved, struct list_head *failed)
-{
-	unsigned long retry;
-	unsigned long nr_failed = 0;
-	int pass = 0;
-	struct page *page;
-	struct page *page2;
-	int swapwrite = current->flags & PF_SWAPWRITE;
-	int rc;
-
-	if (!swapwrite)
-		current->flags |= PF_SWAPWRITE;
-
-redo:
-	retry = 0;
-
-	list_for_each_entry_safe(page, page2, from, lru) {
-		struct page *newpage = NULL;
-		struct address_space *mapping;
-
-		cond_resched();
-
-		rc = 0;
-		if (page_count(page) == 1)
-			/* page was freed from under us. So we are done. */
-			goto next;
-
-		if (to && list_empty(to))
-			break;
-
-		/*
-		 * Skip locked pages during the first two passes to give the
-		 * functions holding the lock time to release the page. Later we
-		 * use lock_page() to have a higher chance of acquiring the
-		 * lock.
-		 */
-		rc = -EAGAIN;
-		if (pass > 2)
-			lock_page(page);
-		else
-			if (TestSetPageLocked(page))
-				goto next;
-
-		/*
-		 * Only wait on writeback if we have already done a pass where
-		 * we we may have triggered writeouts for lots of pages.
-		 */
-		if (pass > 0) {
-			wait_on_page_writeback(page);
-		} else {
-			if (PageWriteback(page))
-				goto unlock_page;
-		}
-
-		/*
-		 * Anonymous pages must have swap cache references otherwise
-		 * the information contained in the page maps cannot be
-		 * preserved.
-		 */
-		if (PageAnon(page) && !PageSwapCache(page)) {
-			if (!add_to_swap(page, GFP_KERNEL)) {
-				rc = -ENOMEM;
-				goto unlock_page;
-			}
-		}
-
-		if (!to) {
-			rc = swap_page(page);
-			goto next;
-		}
-
-		newpage = lru_to_page(to);
-		lock_page(newpage);
-
-		/*
-		 * Pages are properly locked and writeback is complete.
-		 * Try to migrate the page.
-		 */
-		mapping = page_mapping(page);
-		if (!mapping)
-			goto unlock_both;
-
-		if (mapping->a_ops->migratepage) {
-			/*
-			 * Most pages have a mapping and most filesystems
-			 * should provide a migration function. Anonymous
-			 * pages are part of swap space which also has its
-			 * own migration function. This is the most common
-			 * path for page migration.
-			 */
-			rc = mapping->a_ops->migratepage(newpage, page);
-			goto unlock_both;
-                }
-
-		/*
-		 * Default handling if a filesystem does not provide
-		 * a migration function. We can only migrate clean
-		 * pages so try to write out any dirty pages first.
-		 */
-		if (PageDirty(page)) {
-			switch (pageout(page, mapping)) {
-			case PAGE_KEEP:
-			case PAGE_ACTIVATE:
-				goto unlock_both;
-
-			case PAGE_SUCCESS:
-				unlock_page(newpage);
-				goto next;
-
-			case PAGE_CLEAN:
-				; /* try to migrate the page below */
-			}
-                }
-
-		/*
-		 * Buffers are managed in a filesystem specific way.
-		 * We must have no buffers or drop them.
-		 */
-		if (!page_has_buffers(page) ||
-		    try_to_release_page(page, GFP_KERNEL)) {
-			rc = migrate_page(newpage, page);
-			goto unlock_both;
-		}
-
-		/*
-		 * On early passes with mapped pages simply
-		 * retry. There may be a lock held for some
-		 * buffers that may go away. Later
-		 * swap them out.
-		 */
-		if (pass > 4) {
-			/*
-			 * Persistently unable to drop buffers..... As a
-			 * measure of last resort we fall back to
-			 * swap_page().
-			 */
-			unlock_page(newpage);
-			newpage = NULL;
-			rc = swap_page(page);
-			goto next;
-		}
-
-unlock_both:
-		unlock_page(newpage);
-
-unlock_page:
-		unlock_page(page);
-
-next:
-		if (rc == -EAGAIN) {
-			retry++;
-		} else if (rc) {
-			/* Permanent failure */
-			list_move(&page->lru, failed);
-			nr_failed++;
-		} else {
-			if (newpage) {
-				/* Successful migration. Return page to LRU */
-				move_to_lru(newpage);
-			}
-			list_move(&page->lru, moved);
-		}
-	}
-	if (retry && pass++ < 10)
-		goto redo;
-
-	if (!swapwrite)
-		current->flags &= ~PF_SWAPWRITE;
-
-	return nr_failed + retry;
-}
-
-/*
- * Isolate one page from the LRU lists and put it on the
- * indicated list with elevated refcount.
- *
- * Result:
- *  0 = page not on LRU list
- *  1 = page removed from LRU list and added to the specified list.
- */
-int isolate_lru_page(struct page *page)
-{
-	int ret = 0;
-
-	if (PageLRU(page)) {
-		struct zone *zone = page_zone(page);
-		spin_lock_irq(&zone->lru_lock);
-		if (PageLRU(page)) {
-			ret = 1;
-			get_page(page);
-			ClearPageLRU(page);
-			if (PageActive(page))
-				del_page_from_active_list(zone, page);
-			else
-				del_page_from_inactive_list(zone, page);
-		}
-		spin_unlock_irq(&zone->lru_lock);
-	}
-
-	return ret;
-}
-#endif
-
 /*
  * zone->lru_lock is heavily contended.  Some of the functions that
  * shrink the lists perform better by taking out a batch of pages
Index: linux-2.6.16-rc6/include/linux/swap.h
===================================================================
--- linux-2.6.16-rc6.orig/include/linux/swap.h	2006-03-15 18:15:14.000000000 -0800
+++ linux-2.6.16-rc6/include/linux/swap.h	2006-03-15 18:20:20.000000000 -0800
@@ -175,6 +175,21 @@ extern void swap_setup(void);
 extern unsigned long try_to_free_pages(struct zone **, gfp_t);
 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 extern int vm_swappiness;
+extern int remove_mapping(struct address_space *mapping, struct page *page);
+
+/* possible outcome of pageout() */
+typedef enum {
+	/* failed to write page out, page is locked */
+	PAGE_KEEP,
+	/* move page to the active list, page is locked */
+	PAGE_ACTIVATE,
+	/* page has been sent to the disk successfully, page is unlocked */
+	PAGE_SUCCESS,
+	/* page is clean and locked */
+	PAGE_CLEAN,
+} pageout_t;
+
+extern pageout_t pageout(struct page *page, struct address_space *mapping);
 
 #ifdef CONFIG_NUMA
 extern int zone_reclaim_mode;
@@ -188,25 +203,6 @@ static inline int zone_reclaim(struct zo
 }
 #endif
 
-#ifdef CONFIG_MIGRATION
-extern int isolate_lru_page(struct page *p);
-extern unsigned long putback_lru_pages(struct list_head *l);
-extern int migrate_page(struct page *, struct page *);
-extern void migrate_page_copy(struct page *, struct page *);
-extern int migrate_page_remove_references(struct page *, struct page *, int);
-extern unsigned long migrate_pages(struct list_head *l, struct list_head *t,
-		struct list_head *moved, struct list_head *failed);
-extern int fail_migrate_page(struct page *, struct page *);
-#else
-static inline int isolate_lru_page(struct page *p) { return -ENOSYS; }
-static inline int putback_lru_pages(struct list_head *l) { return 0; }
-static inline int migrate_pages(struct list_head *l, struct list_head *t,
-	struct list_head *moved, struct list_head *failed) { return -ENOSYS; }
-/* Possible settings for the migrate_page() method in address_operations */
-#define migrate_page NULL
-#define fail_migrate_page NULL
-#endif
-
 #ifdef CONFIG_MMU
 /* linux/mm/shmem.c */
 extern int shmem_unuse(swp_entry_t entry, struct page *page);
Index: linux-2.6.16-rc6/mm/mempolicy.c
===================================================================
--- linux-2.6.16-rc6.orig/mm/mempolicy.c	2006-03-15 18:15:14.000000000 -0800
+++ linux-2.6.16-rc6/mm/mempolicy.c	2006-03-15 18:21:55.000000000 -0800
@@ -86,6 +86,7 @@
 #include <linux/swap.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
+#include <linux/migrate.h>
 
 #include <asm/tlbflush.h>
 #include <asm/uaccess.h>
@@ -95,9 +96,6 @@
 #define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1)		/* Invert check for nodemask */
 #define MPOL_MF_STATS (MPOL_MF_INTERNAL << 2)		/* Gather statistics */
 
-/* The number of pages to migrate per call to migrate_pages() */
-#define MIGRATE_CHUNK_SIZE 256
-
 static struct kmem_cache *policy_cache;
 static struct kmem_cache *sn_cache;
 
@@ -331,6 +329,7 @@ check_range(struct mm_struct *mm, unsign
 	struct vm_area_struct *first, *vma, *prev;
 
 	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+#ifdef CONFIG_MIGRATION
 		/* Must have swap device for migration */
 		if (nr_swap_pages <= 0)
 			return ERR_PTR(-ENODEV);
@@ -342,6 +341,9 @@ check_range(struct mm_struct *mm, unsign
 		 * pages that may be busy.
 		 */
 		lru_add_drain_all();
+#else
+		return -ENOSYS;
+#endif
 	}
 
 	first = find_vma(mm, start);
@@ -553,10 +555,10 @@ long do_get_mempolicy(int *policy, nodem
 /*
  * page migration
  */
-
 static void migrate_page_add(struct page *page, struct list_head *pagelist,
 				unsigned long flags)
 {
+#ifdef CONFIG_MIGRATION
 	/*
 	 * Avoid migrating a page that is shared with others.
 	 */
@@ -564,80 +566,10 @@ static void migrate_page_add(struct page
 		if (isolate_lru_page(page))
 			list_add_tail(&page->lru, pagelist);
 	}
+#endif
 }
 
-/*
- * Migrate the list 'pagelist' of pages to a certain destination.
- *
- * Specify destination with either non-NULL vma or dest_node >= 0
- * Return the number of pages not migrated or error code
- */
-static int migrate_pages_to(struct list_head *pagelist,
-			struct vm_area_struct *vma, int dest)
-{
-	LIST_HEAD(newlist);
-	LIST_HEAD(moved);
-	LIST_HEAD(failed);
-	int err = 0;
-	unsigned long offset = 0;
-	int nr_pages;
-	struct page *page;
-	struct list_head *p;
-
-redo:
-	nr_pages = 0;
-	list_for_each(p, pagelist) {
-		if (vma) {
-			/*
-			 * The address passed to alloc_page_vma is used to
-			 * generate the proper interleave behavior. We fake
-			 * the address here by an increasing offset in order
-			 * to get the proper distribution of pages.
-			 *
-			 * No decision has been made as to which page
-			 * a certain old page is moved to so we cannot
-			 * specify the correct address.
-			 */
-			page = alloc_page_vma(GFP_HIGHUSER, vma,
-					offset + vma->vm_start);
-			offset += PAGE_SIZE;
-		}
-		else
-			page = alloc_pages_node(dest, GFP_HIGHUSER, 0);
-
-		if (!page) {
-			err = -ENOMEM;
-			goto out;
-		}
-		list_add_tail(&page->lru, &newlist);
-		nr_pages++;
-		if (nr_pages > MIGRATE_CHUNK_SIZE)
-			break;
-	}
-	err = migrate_pages(pagelist, &newlist, &moved, &failed);
-
-	putback_lru_pages(&moved);	/* Call release pages instead ?? */
-
-	if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist))
-		goto redo;
-out:
-	/* Return leftover allocated pages */
-	while (!list_empty(&newlist)) {
-		page = list_entry(newlist.next, struct page, lru);
-		list_del(&page->lru);
-		__free_page(page);
-	}
-	list_splice(&failed, pagelist);
-	if (err < 0)
-		return err;
-
-	/* Calculate number of leftover pages */
-	nr_pages = 0;
-	list_for_each(p, pagelist)
-		nr_pages++;
-	return nr_pages;
-}
-
+#ifdef CONFIG_MIGRATION
 /*
  * Migrate pages from one node to a target node.
  * Returns error or the number of pages not migrated.
@@ -661,6 +593,7 @@ int migrate_to_node(struct mm_struct *mm
 	}
 	return err;
 }
+#endif
 
 /*
  * Move pages between the two nodesets so as to preserve the physical
@@ -671,6 +604,7 @@ int migrate_to_node(struct mm_struct *mm
 int do_migrate_pages(struct mm_struct *mm,
 	const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags)
 {
+#ifdef CONFIG_MIGRATION
 	LIST_HEAD(pagelist);
 	int busy = 0;
 	int err = 0;
@@ -742,6 +676,9 @@ int do_migrate_pages(struct mm_struct *m
 	if (err < 0)
 		return err;
 	return busy;
+#else
+	return -ENOSYS;
+#endif
 }
 
 long do_mbind(unsigned long start, unsigned long len,
@@ -802,12 +739,15 @@ long do_mbind(unsigned long start, unsig
 
 		err = mbind_range(vma, start, end, new);
 
+#ifdef CONFIG_MIGRATION
 		if (!list_empty(&pagelist))
 			nr_failed = migrate_pages_to(&pagelist, vma, -1);
+#endif
 
 		if (!err && nr_failed && (flags & MPOL_MF_STRICT))
 			err = -EIO;
 	}
+
 	if (!list_empty(&pagelist))
 		putback_lru_pages(&pagelist);
 
Index: linux-2.6.16-rc6/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- linux-2.6.16-rc6.orig/fs/xfs/linux-2.6/xfs_buf.c	2006-03-15 18:15:13.000000000 -0800
+++ linux-2.6.16-rc6/fs/xfs/linux-2.6/xfs_buf.c	2006-03-15 18:15:43.000000000 -0800
@@ -29,6 +29,7 @@
 #include <linux/blkdev.h>
 #include <linux/hash.h>
 #include <linux/kthread.h>
+#include <linux/migrate.h>
 #include "xfs_linux.h"
 
 STATIC kmem_zone_t *xfs_buf_zone;
Index: linux-2.6.16-rc6/fs/buffer.c
===================================================================
--- linux-2.6.16-rc6.orig/fs/buffer.c	2006-03-15 18:15:13.000000000 -0800
+++ linux-2.6.16-rc6/fs/buffer.c	2006-03-15 18:19:29.000000000 -0800
@@ -3051,68 +3051,6 @@ asmlinkage long sys_bdflush(int func, lo
 }
 
 /*
- * Migration function for pages with buffers. This function can only be used
- * if the underlying filesystem guarantees that no other references to "page"
- * exist.
- */
-#ifdef CONFIG_MIGRATION
-int buffer_migrate_page(struct page *newpage, struct page *page)
-{
-	struct address_space *mapping = page->mapping;
-	struct buffer_head *bh, *head;
-	int rc;
-
-	if (!mapping)
-		return -EAGAIN;
-
-	if (!page_has_buffers(page))
-		return migrate_page(newpage, page);
-
-	head = page_buffers(page);
-
-	rc = migrate_page_remove_references(newpage, page, 3);
-	if (rc)
-		return rc;
-
-	bh = head;
-	do {
-		get_bh(bh);
-		lock_buffer(bh);
-		bh = bh->b_this_page;
-
-	} while (bh != head);
-
-	ClearPagePrivate(page);
-	set_page_private(newpage, page_private(page));
-	set_page_private(page, 0);
-	put_page(page);
-	get_page(newpage);
-
-	bh = head;
-	do {
-		set_bh_page(bh, newpage, bh_offset(bh));
-		bh = bh->b_this_page;
-
-	} while (bh != head);
-
-	SetPagePrivate(newpage);
-
-	migrate_page_copy(newpage, page);
-
-	bh = head;
-	do {
-		unlock_buffer(bh);
- 		put_bh(bh);
-		bh = bh->b_this_page;
-
-	} while (bh != head);
-
-	return 0;
-}
-EXPORT_SYMBOL(buffer_migrate_page);
-#endif
-
-/*
  * Buffer-head allocation
  */
 static kmem_cache_t *bh_cachep;
Index: linux-2.6.16-rc6/mm/Kconfig
===================================================================
--- linux-2.6.16-rc6.orig/mm/Kconfig	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/mm/Kconfig	2006-03-15 18:15:43.000000000 -0800
@@ -137,5 +137,11 @@ config SPLIT_PTLOCK_CPUS
 # support for page migration
 #
 config MIGRATION
+	bool "Page migration"
 	def_bool y if NUMA || SPARSEMEM || DISCONTIGMEM
 	depends on SWAP
+	help
+	  Allows the migration of the physical location of pages of processes
+	  while the virtual addresses are not changed. This is useful for
+	  example on NUMA systems to put pages nearer to the processors accessing
+	  the page.
Index: linux-2.6.16-rc6/mm/swap_state.c
===================================================================
--- linux-2.6.16-rc6.orig/mm/swap_state.c	2006-03-11 14:12:55.000000000 -0800
+++ linux-2.6.16-rc6/mm/swap_state.c	2006-03-15 18:27:40.000000000 -0800
@@ -15,6 +15,7 @@
 #include <linux/buffer_head.h>
 #include <linux/backing-dev.h>
 #include <linux/pagevec.h>
+#include <linux/migrate.h>
 
 #include <asm/pgtable.h>
 
Index: linux-2.6.16-rc6/include/linux/migrate.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.16-rc6/include/linux/migrate.h	2006-03-15 18:27:37.000000000 -0800
@@ -0,0 +1,31 @@
+#ifndef _LINUX_MIGRATE_H
+#define _LINUX_MIGRATE_H
+
+#include <linux/config.h>
+#include <linux/mm.h>
+
+#ifdef CONFIG_MIGRATION
+extern int isolate_lru_page(struct page *p);
+extern int putback_lru_pages(struct list_head *l);
+extern int migrate_page(struct page *, struct page *);
+extern void migrate_page_copy(struct page *, struct page *);
+extern int migrate_page_remove_references(struct page *, struct page *, int);
+extern int migrate_pages(struct list_head *l, struct list_head *t,
+		struct list_head *moved, struct list_head *failed);
+int migrate_pages_to(struct list_head *pagelist,
+			struct vm_area_struct *vma, int dest);
+extern int fail_migrate_page(struct page *, struct page *);
+
+#else
+
+static inline int isolate_lru_page(struct page *p) { return -ENOSYS; }
+static inline int putback_lru_pages(struct list_head *l) { return 0; }
+static inline int migrate_pages(struct list_head *l, struct list_head *t,
+	struct list_head *moved, struct list_head *failed) { return -ENOSYS; }
+
+/* Possible settings for the migrate_page() method in address_operations */
+#define migrate_page NULL
+#define fail_migrate_page NULL
+
+#endif /* CONFIG_MIGRATION */
+#endif /* _LINUX_MIGRATE_H */

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Re: page migration reorg patch

[Andrew Morton]

Christoph Lameter <clameter@sgi.com> wrote:
>
> On Wed, 15 Mar 2006, Andrew Morton wrote:
> 
>  > If you can rework this patch against
>  > http://www.zip.com.au/~akpm/linux/patches/stuff/x.bz2 (my current queue up
>  > to and including slab-leaks3-locking-fix.patch, against 2.6.16-rc6) then
>  > I'll be able to insert it in the right place and then fix up subsequent
>  > fallout, thanks.
> 
>  BTW compilation fails with:
> 
>  drivers/scsi/sata_vsc.c: At top level:
>  drivers/scsi/sata_vsc.c:254: unknown field `eh_timed_out' specified in 
>  initializer
>  drivers/scsi/sata_vsc.c:254: warning: initialization from incompatible 
>  pointer type
>

That's fairly typical for a new batch of git pulls :(

> 
>  The patch (including the two amendments) against the x.bz2 patch:

Thanks for doing that.

Yes, mm/mempolicy.c did get a bit uglified.

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Re: page migration reorg patch

[Andrew Morton]

Christoph Lameter <clameter@sgi.com> wrote:
>
> This patch centralizes the page migration functions in anticipation of
>  additional tinkering. Creates a new file mm/migrate.c


mm/migrate.c: In function `migrate_page_remove_references':
mm/migrate.c:200: warning: implicit declaration of function `__put_page'
mm/migrate.c: In function `isolate_lru_page':
mm/migrate.c:482: warning: implicit declaration of function `TestClearPageLRU'


Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 mm/migrate.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletion(-)

diff -puN mm/migrate.c~page-migration-reorg-fixes mm/migrate.c
--- devel/mm/migrate.c~page-migration-reorg-fixes	2006-03-16 01:28:18.000000000 -0800
+++ devel-akpm/mm/migrate.c	2006-03-16 01:28:18.000000000 -0800
@@ -26,6 +26,8 @@
 #include <linux/cpuset.h>
 #include <linux/swapops.h>
 
+#include "internal.h"
+
 /* The maximum number of pages to take off the LRU for migration */
 #define MIGRATE_CHUNK_SIZE 256
 
@@ -479,9 +481,10 @@ int isolate_lru_page(struct page *page)
 	if (PageLRU(page)) {
 		struct zone *zone = page_zone(page);
 		spin_lock_irq(&zone->lru_lock);
-		if (TestClearPageLRU(page)) {
+		if (PageLRU(page)) {
 			ret = 1;
 			get_page(page);
+			ClearPageLRU(page);
 			if (PageActive(page))
 				del_page_from_active_list(zone, page);
 			else
_


This wasn't compile tested and it wasn't runtime tested.  But the worrisome
part is that the patch failed to bring over changes which were made by
earlier patches.  So it possibly reverts important changes.

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