[PATCH] page migration: use allocator function for migrate_pages()
Instead of passing a list of new pages, pass a function to allocate a new
page. This allows the correct placement of MPOL_INTERLEAVE pages during page
migration. It also further simplifies the callers of migrate pages.
migrate_pages() becomes similar to migrate_pages_to() so drop
migrate_pages_to(). The batching of new page allocations becomes unnecessary.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Jes Sorensen <jes@trained-monkey.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/migrate.c b/mm/migrate.c
index d3a1810..251a8d1 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -28,9 +28,6 @@
#include "internal.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))
/*
@@ -587,18 +584,23 @@
* Obtain the lock on page, remove all ptes and migrate the page
* to the newly allocated page in newpage.
*/
-static int unmap_and_move(struct page *newpage, struct page *page, int force)
+static int unmap_and_move(new_page_t get_new_page, unsigned long private,
+ struct page *page, int force)
{
int rc = 0;
+ struct page *newpage = get_new_page(page, private);
+
+ if (!newpage)
+ return -ENOMEM;
if (page_count(page) == 1)
/* page was freed from under us. So we are done. */
- goto ret;
+ goto move_newpage;
rc = -EAGAIN;
if (TestSetPageLocked(page)) {
if (!force)
- goto ret;
+ goto move_newpage;
lock_page(page);
}
@@ -622,7 +624,7 @@
remove_migration_ptes(page, page);
unlock:
unlock_page(page);
-ret:
+
if (rc != -EAGAIN) {
/*
* A page that has been migrated has all references
@@ -632,29 +634,33 @@
*/
list_del(&page->lru);
move_to_lru(page);
-
- list_del(&newpage->lru);
- move_to_lru(newpage);
}
+
+move_newpage:
+ /*
+ * Move the new page to the LRU. If migration was not successful
+ * then this will free the page.
+ */
+ move_to_lru(newpage);
return rc;
}
/*
* 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 isolated pages
- * can be moved to.
+ * The function takes one list of pages to migrate and a function
+ * that determines from the page to be migrated and the private data
+ * the target of the move and allocates the page.
*
* The function returns after 10 attempts or if no pages
* are movable anymore because to has become empty
* or no retryable pages exist anymore. All pages will be
* retruned to the LRU or freed.
*
- * Return: Number of pages not migrated.
+ * Return: Number of pages not migrated or error code.
*/
-int migrate_pages(struct list_head *from, struct list_head *to)
+int migrate_pages(struct list_head *from,
+ new_page_t get_new_page, unsigned long private)
{
int retry = 1;
int nr_failed = 0;
@@ -671,15 +677,14 @@
retry = 0;
list_for_each_entry_safe(page, page2, from, lru) {
-
- if (list_empty(to))
- break;
-
cond_resched();
- rc = unmap_and_move(lru_to_page(to), page, pass > 2);
+ rc = unmap_and_move(get_new_page, private,
+ page, pass > 2);
switch(rc) {
+ case -ENOMEM:
+ goto out;
case -EAGAIN:
retry++;
break;
@@ -692,72 +697,16 @@
}
}
}
-
+ rc = 0;
+out:
if (!swapwrite)
current->flags &= ~PF_SWAPWRITE;
putback_lru_pages(from);
+
+ if (rc)
+ return rc;
+
return nr_failed + retry;
}
-/*
- * 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);
- int err = 0;
- unsigned long offset = 0;
- int nr_pages;
- int nr_failed = 0;
- 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);
-
- if (err >= 0) {
- nr_failed += err;
- if (list_empty(&newlist) && !list_empty(pagelist))
- goto redo;
- }
-out:
-
- /* Calculate number of leftover pages */
- list_for_each(p, pagelist)
- nr_failed++;
- return nr_failed;
-}