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Subject[PATCH v3 07/10] migration: clean up unmap_and_move
Date
The unmap_and_move is one of big messy functions.
This patch try to clean up.

It can help readability and make unmap_and_move_ilru simple.
unmap_and_move_ilru will be introduced by next patch.

Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
mm/migrate.c | 82 +++++++++++++++++++++++++++++++++------------------------
1 files changed, 47 insertions(+), 35 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 874c081..3aec310 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -645,38 +645,18 @@ static int move_to_new_page(struct page *newpage, struct page *page,
return rc;
}

-/*
- * Obtain the lock on page, remove all ptes and migrate the page
- * to the newly allocated page in newpage.
- */
-static int unmap_and_move(new_page_t get_new_page, unsigned long private,
- struct page *page, int force, bool offlining, bool sync)
+static int __unmap_and_move(struct page *page, struct page *newpage,
+ int force, bool offlining, bool sync)
{
- int rc = 0;
- int *result = NULL;
- struct page *newpage = get_new_page(page, private, &result);
+ int rc = -EAGAIN;
int remap_swapcache = 1;
int charge = 0;
struct mem_cgroup *mem;
struct anon_vma *anon_vma = NULL;

- if (!newpage)
- return -ENOMEM;
-
- if (page_count(page) == 1) {
- /* page was freed from under us. So we are done. */
- goto move_newpage;
- }
- if (unlikely(PageTransHuge(page)))
- if (unlikely(split_huge_page(page)))
- goto move_newpage;
-
- /* prepare cgroup just returns 0 or -ENOMEM */
- rc = -EAGAIN;
-
if (!trylock_page(page)) {
if (!force || !sync)
- goto move_newpage;
+ goto out;

/*
* It's not safe for direct compaction to call lock_page.
@@ -692,7 +672,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
* altogether.
*/
if (current->flags & PF_MEMALLOC)
- goto move_newpage;
+ goto out;

lock_page(page);
}
@@ -813,9 +793,13 @@ uncharge:
mem_cgroup_end_migration(mem, page, newpage, rc == 0);
unlock:
unlock_page(page);
+out:
+ return rc;
+}

-move_newpage:
- if (rc != -EAGAIN) {
+static void __put_lru_pages(struct page *page, struct page *newpage)
+{
+ if (page != NULL) {
/*
* A page that has been migrated has all references
* removed and will be freed. A page that has not been
@@ -827,20 +811,48 @@ move_newpage:
page_is_file_cache(page));
putback_lru_page(page);
}
-
/*
* Move the new page to the LRU. If migration was not successful
* then this will free the page.
*/
putback_lru_page(newpage);
+}

- if (result) {
- if (rc)
- *result = rc;
- else
- *result = page_to_nid(newpage);
- }
- return rc;
+/*
+ * Obtain the lock on page, remove all ptes and migrate the page
+ * to the newly allocated page in newpage.
+ */
+static int unmap_and_move(new_page_t get_new_page, unsigned long private,
+ struct page *page, int force, bool offlining, bool sync)
+{
+ int rc = 0;
+ int *result = NULL;
+ struct page *newpage = get_new_page(page, private, &result);
+
+ if (!newpage)
+ return -ENOMEM;
+
+ if (page_count(page) == 1) {
+ /* page was freed from under us. So we are done. */
+ goto out;
+ }
+
+ if (unlikely(PageTransHuge(page)))
+ if (unlikely(split_huge_page(page)))
+ goto out;
+
+ rc = __unmap_and_move(page, newpage, force, offlining, sync);
+ if (rc == -EAGAIN)
+ page = NULL;
+out:
+ __put_lru_pages(page, newpage);
+ if (result) {
+ if (rc)
+ *result = rc;
+ else
+ *result = page_to_nid(newpage);
+ }
+ return rc;
}

/*
--
1.7.0.4


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