[PATCH] SwapMig: Extend parameters for migrate_pages()

Extend the parameters of migrate_pages() to allow the caller control over the fate of successfully migrated or impossible to migrate pages. Swap migration and direct migration will have the same interface after this patch so that patches can be independently applied to the policy layer and the core migration code. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] SwapMig: Extend parameters for migrate_pages()
Extend the parameters of migrate_pages() to allow the caller control over the fate of successfully migrated or impossible to migrate pages. Swap migration and direct migration will have the same interface after this patch so that patches can be independently applied to the policy layer and the core migration code. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Christoph Lameter · Linus Torvalds
1 parent ee27497df3
Showing 3 changed files with 32 additions and 15 deletions Side-by-side Diff
include/linux/swap.h
mm/mempolicy.c
mm/vmscan.c
@@ -178,7 +178,8 @@
 #ifdef CONFIG_MIGRATION
 extern int isolate_lru_page(struct page *p);
 extern int putback_lru_pages(struct list_head *l);
-extern int migrate_pages(struct list_head *l, struct list_head *t);
+extern int migrate_pages(struct list_head *l, struct list_head *t,
+		struct list_head *moved, struct list_head *failed);
 #endif
  
 #ifdef CONFIG_MMU
@@ -429,6 +429,19 @@
 	return mpol_check_policy(mode, nodes);
 }
  
+static int swap_pages(struct list_head *pagelist)
+{
+	LIST_HEAD(moved);
+	LIST_HEAD(failed);
+	int n;
+
+	n = migrate_pages(pagelist, NULL, &moved, &failed);
+	putback_lru_pages(&failed);
+	putback_lru_pages(&moved);
+
+	return n;
+}
+
 long do_mbind(unsigned long start, unsigned long len,
 		unsigned long mode, nodemask_t *nmask, unsigned long flags)
 {
  
@@ -481,10 +494,13 @@
 	      (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) ? &pagelist : NULL);
 	err = PTR_ERR(vma);
 	if (!IS_ERR(vma)) {
+		int nr_failed = 0;
+
 		err = mbind_range(vma, start, end, new);
 		if (!list_empty(&pagelist))
-			migrate_pages(&pagelist, NULL);
-		if (!err && !list_empty(&pagelist) && (flags & MPOL_MF_STRICT))
+			nr_failed = swap_pages(&pagelist);
+
+		if (!err && nr_failed && (flags & MPOL_MF_STRICT))
 			err = -EIO;
 	}
 	if (!list_empty(&pagelist))
  
  
@@ -635,11 +651,12 @@
 	down_read(&mm->mmap_sem);
 	check_range(mm, mm->mmap->vm_start, TASK_SIZE, &nodes,
 			flags | MPOL_MF_DISCONTIG_OK, &pagelist);
+
 	if (!list_empty(&pagelist)) {
-		migrate_pages(&pagelist, NULL);
-		if (!list_empty(&pagelist))
-			count = putback_lru_pages(&pagelist);
+		count = swap_pages(&pagelist);
+		putback_lru_pages(&pagelist);
 	}
+
 	up_read(&mm->mmap_sem);
 	return count;
 }
@@ -670,10 +670,10 @@
  * list. The direct migration patchset
  * extends this function to avoid the use of swap.
  */
-int migrate_pages(struct list_head *l, struct list_head *t)
+int migrate_pages(struct list_head *from, struct list_head *to,
+		  struct list_head *moved, struct list_head *failed)
 {
 	int retry;
-	LIST_HEAD(failed);
 	int nr_failed = 0;
 	int pass = 0;
 	struct page *page;
  
@@ -686,12 +686,12 @@
 redo:
 	retry = 0;
  
-	list_for_each_entry_safe(page, page2, l, lru) {
+	list_for_each_entry_safe(page, page2, from, lru) {
 		cond_resched();
  
 		if (page_count(page) == 1) {
 			/* page was freed from under us. So we are done. */
-			move_to_lru(page);
+			list_move(&page->lru, moved);
 			continue;
 		}
 		/*
@@ -722,7 +722,7 @@
 		if (PageAnon(page) && !PageSwapCache(page)) {
 			if (!add_to_swap(page, GFP_KERNEL)) {
 				unlock_page(page);
-				list_move(&page->lru, &failed);
+				list_move(&page->lru, failed);
 				nr_failed++;
 				continue;
 			}
  
@@ -732,8 +732,10 @@
 		 * Page is properly locked and writeback is complete.
 		 * Try to migrate the page.
 		 */
-		if (!swap_page(page))
+		if (!swap_page(page)) {
+			list_move(&page->lru, moved);
 			continue;
+		}
 retry_later:
 		retry++;
 	}
@@ -742,9 +744,6 @@
  
 	if (!swapwrite)
 		current->flags &= ~PF_SWAPWRITE;
-
-	if (!list_empty(&failed))
-		list_splice(&failed, l);
  
 	return nr_failed + retry;
 }
...	...	@@ -178,7 +178,8 @@
178	178	#ifdef CONFIG_MIGRATION
179	179	extern int isolate_lru_page(struct page *p);
180	180	extern int putback_lru_pages(struct list_head *l);
181		-extern int migrate_pages(struct list_head l, struct list_head t);
	181	+extern int migrate_pages(struct list_head l, struct list_head t,
	182	+ struct list_head moved, struct list_head failed);
182	183	#endif
183	184
184	185	#ifdef CONFIG_MMU
...	...	@@ -429,6 +429,19 @@
429	429	return mpol_check_policy(mode, nodes);
430	430	}
431	431
	432	+static int swap_pages(struct list_head *pagelist)
	433	+{
	434	+ LIST_HEAD(moved);
	435	+ LIST_HEAD(failed);
	436	+ int n;
	437	+
	438	+ n = migrate_pages(pagelist, NULL, &moved, &failed);
	439	+ putback_lru_pages(&failed);
	440	+ putback_lru_pages(&moved);
	441	+
	442	+ return n;
	443	+}
	444	+
432	445	long do_mbind(unsigned long start, unsigned long len,
433	446	unsigned long mode, nodemask_t *nmask, unsigned long flags)
434	447	{
435	448
...	...	@@ -481,10 +494,13 @@
481	494	(flags & (MPOL_MF_MOVE \| MPOL_MF_MOVE_ALL)) ? &pagelist : NULL);
482	495	err = PTR_ERR(vma);
483	496	if (!IS_ERR(vma)) {
	497	+ int nr_failed = 0;
	498	+
484	499	err = mbind_range(vma, start, end, new);
485	500	if (!list_empty(&pagelist))
486		- migrate_pages(&pagelist, NULL);
487		- if (!err && !list_empty(&pagelist) && (flags & MPOL_MF_STRICT))
	501	+ nr_failed = swap_pages(&pagelist);
	502	+
	503	+ if (!err && nr_failed && (flags & MPOL_MF_STRICT))
488	504	err = -EIO;
489	505	}
490	506	if (!list_empty(&pagelist))
491	507
492	508
...	...	@@ -635,11 +651,12 @@
635	651	down_read(&mm->mmap_sem);
636	652	check_range(mm, mm->mmap->vm_start, TASK_SIZE, &nodes,
637	653	flags \| MPOL_MF_DISCONTIG_OK, &pagelist);
	654	+
638	655	if (!list_empty(&pagelist)) {
639		- migrate_pages(&pagelist, NULL);
640		- if (!list_empty(&pagelist))
641		- count = putback_lru_pages(&pagelist);
	656	+ count = swap_pages(&pagelist);
	657	+ putback_lru_pages(&pagelist);
642	658	}
	659	+
643	660	up_read(&mm->mmap_sem);
644	661	return count;
645	662	}
...	...	@@ -670,10 +670,10 @@
670	670	* list. The direct migration patchset
671	671	* extends this function to avoid the use of swap.
672	672	*/
673		-int migrate_pages(struct list_head l, struct list_head t)
	673	+int migrate_pages(struct list_head from, struct list_head to,
	674	+ struct list_head moved, struct list_head failed)
674	675	{
675	676	int retry;
676		- LIST_HEAD(failed);
677	677	int nr_failed = 0;
678	678	int pass = 0;
679	679	struct page *page;
680	680
...	...	@@ -686,12 +686,12 @@
686	686	redo:
687	687	retry = 0;
688	688
689		- list_for_each_entry_safe(page, page2, l, lru) {
	689	+ list_for_each_entry_safe(page, page2, from, lru) {
690	690	cond_resched();
691	691
692	692	if (page_count(page) == 1) {
693	693	/* page was freed from under us. So we are done. */
694		- move_to_lru(page);
	694	+ list_move(&page->lru, moved);
695	695	continue;
696	696	}
697	697	/*
...	...	@@ -722,7 +722,7 @@
722	722	if (PageAnon(page) && !PageSwapCache(page)) {
723	723	if (!add_to_swap(page, GFP_KERNEL)) {
724	724	unlock_page(page);
725		- list_move(&page->lru, &failed);
	725	+ list_move(&page->lru, failed);
726	726	nr_failed++;
727	727	continue;
728	728	}
729	729
...	...	@@ -732,8 +732,10 @@
732	732	* Page is properly locked and writeback is complete.
733	733	* Try to migrate the page.
734	734	*/
735		- if (!swap_page(page))
	735	+ if (!swap_page(page)) {
	736	+ list_move(&page->lru, moved);
736	737	continue;
	738	+ }
737	739	retry_later:
738	740	retry++;
739	741	}
...	...	@@ -742,9 +744,6 @@
742	744
743	745	if (!swapwrite)
744	746	current->flags &= ~PF_SWAPWRITE;
745		-
746		- if (!list_empty(&failed))
747		- list_splice(&failed, l);
748	747
749	748	return nr_failed + retry;
750	749	}