[PATCH] page migration reorg
Centralize 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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 96195dc..e93cc74 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -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;
@@ -331,17 +329,10 @@
struct vm_area_struct *first, *vma, *prev;
if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
- /* Must have swap device for migration */
- if (nr_swap_pages <= 0)
- return ERR_PTR(-ENODEV);
- /*
- * Clear the LRU lists so pages can be isolated.
- * Note that pages may be moved off the LRU after we have
- * drained them. Those pages will fail to migrate like other
- * pages that may be busy.
- */
- lru_add_drain_all();
+ err = migrate_prep();
+ if (err)
+ return ERR_PTR(err);
}
first = find_vma(mm, start);
@@ -550,92 +541,18 @@
return err;
}
+#ifdef CONFIG_MIGRATION
/*
* page migration
*/
-
static void migrate_page_add(struct page *page, struct list_head *pagelist,
unsigned long flags)
{
/*
* Avoid migrating a page that is shared with others.
*/
- if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1) {
- if (isolate_lru_page(page))
- list_add_tail(&page->lru, pagelist);
- }
-}
-
-/*
- * 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;
+ if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1)
+ isolate_lru_page(page, pagelist);
}
/*
@@ -742,8 +659,23 @@
if (err < 0)
return err;
return busy;
+
}
+#else
+
+static void migrate_page_add(struct page *page, struct list_head *pagelist,
+ unsigned long flags)
+{
+}
+
+int do_migrate_pages(struct mm_struct *mm,
+ const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags)
+{
+ return -ENOSYS;
+}
+#endif
+
long do_mbind(unsigned long start, unsigned long len,
unsigned long mode, nodemask_t *nmask, unsigned long flags)
{
@@ -808,6 +740,7 @@
if (!err && nr_failed && (flags & MPOL_MF_STRICT))
err = -EIO;
}
+
if (!list_empty(&pagelist))
putback_lru_pages(&pagelist);