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-rw-r--r--include/linux/swap.h2
-rw-r--r--mm/Kconfig7
-rw-r--r--mm/vmscan.c20
3 files changed, 20 insertions, 9 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 893096e67bd..117add066f0 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -178,7 +178,9 @@ extern int vm_swappiness;
extern int isolate_lru_page(struct page *p);
extern int putback_lru_pages(struct list_head *l);
+#ifdef CONFIG_MIGRATION
extern int migrate_pages(struct list_head *l, struct list_head *t);
+#endif
#ifdef CONFIG_MMU
/* linux/mm/shmem.c */
diff --git a/mm/Kconfig b/mm/Kconfig
index b3db11f137e..a9cb80ae640 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -132,3 +132,10 @@ config SPLIT_PTLOCK_CPUS
default "4096" if ARM && !CPU_CACHE_VIPT
default "4096" if PARISC && !PA20
default "4"
+
+#
+# support for page migration
+#
+config MIGRATION
+ def_bool y if NUMA || SPARSEMEM || DISCONTIGMEM
+ depends on SWAP
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a537a7f1635..58270aea669 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -568,6 +568,7 @@ keep:
return reclaimed;
}
+#ifdef CONFIG_MIGRATION
/*
* swapout a single page
* page is locked upon entry, unlocked on exit
@@ -656,8 +657,9 @@ redo:
/*
* 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.
+ * functions holding the lock time to release the page. Later we
+ * use lock_page() to have a higher chance of acquiring the
+ * lock.
*/
if (pass > 2)
lock_page(page);
@@ -669,15 +671,15 @@ redo:
* 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)
+ if (pass > 0) {
wait_on_page_writeback(page);
- else
+ } else {
if (PageWriteback(page)) {
unlock_page(page);
goto retry_later;
}
+ }
-#ifdef CONFIG_SWAP
if (PageAnon(page) && !PageSwapCache(page)) {
if (!add_to_swap(page)) {
unlock_page(page);
@@ -686,16 +688,15 @@ redo:
continue;
}
}
-#endif /* CONFIG_SWAP */
/*
* Page is properly locked and writeback is complete.
* Try to migrate the page.
*/
- if (swap_page(page)) {
+ if (!swap_page(page))
+ continue;
retry_later:
- retry++;
- }
+ retry++;
}
if (retry && pass++ < 10)
goto redo;
@@ -708,6 +709,7 @@ retry_later:
return nr_failed + retry;
}
+#endif
/*
* zone->lru_lock is heavily contended. Some of the functions that