Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d0d96328 authored Jan 08, 2006 by Christoph Lameter Committed by Linus Torvalds Jan 08, 2006

[PATCH] SwapMig: Switch error handling in migrate_pages to use -Exx



Use -Exxx instead of numeric return codes and cleanup the code in
migrate_pages() using -Exx error codes.

Consolidate successful migration handling

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent d4984711

mm/vmscan.c

+34 −22

Original line number	Original line	Diff line number	Diff line
	@@ -606,10 +606,6 @@ int putback_lru_pages(struct list_head *l)
	/*		/*
	* swapout a single page		* swapout a single page
	* page is locked upon entry, unlocked on exit		* page is locked upon entry, unlocked on exit
	*
	* return codes:
	* 0 = complete
	* 1 = retry
	*/		*/
	static int swap_page(struct page *page)		static int swap_page(struct page *page)
	{		{
	@@ -650,7 +646,7 @@ static int swap_page(struct page *page)
	unlock_page(page);		unlock_page(page);

	retry:		retry:
	return 1;		return -EAGAIN;
	}		}
	/*		/*
	* migrate_pages		* migrate_pages
	@@ -669,6 +665,8 @@ static int swap_page(struct page *page)
	* is only swapping out pages and never touches the second		* is only swapping out pages and never touches the second
	* list. The direct migration patchset		* list. The direct migration patchset
	* extends this function to avoid the use of swap.		* extends this function to avoid the use of swap.
			*
			* Return: Number of pages not migrated when "to" ran empty.
	*/		*/
	int migrate_pages(struct list_head from, struct list_head to,		int migrate_pages(struct list_head from, struct list_head to,
	struct list_head moved, struct list_head failed)		struct list_head moved, struct list_head failed)
	@@ -679,6 +677,7 @@ int migrate_pages(struct list_head from, struct list_head to,
	struct page *page;		struct page *page;
	struct page *page2;		struct page *page2;
	int swapwrite = current->flags & PF_SWAPWRITE;		int swapwrite = current->flags & PF_SWAPWRITE;
			int rc;

	if (!swapwrite)		if (!swapwrite)
	current->flags \|= PF_SWAPWRITE;		current->flags \|= PF_SWAPWRITE;
	@@ -689,22 +688,23 @@ int migrate_pages(struct list_head from, struct list_head to,
	list_for_each_entry_safe(page, page2, from, lru) {		list_for_each_entry_safe(page, page2, from, lru) {
	cond_resched();		cond_resched();

	if (page_count(page) == 1) {		rc = 0;
			if (page_count(page) == 1)
	/* page was freed from under us. So we are done. */		/* page was freed from under us. So we are done. */
	list_move(&page->lru, moved);		goto next;
	continue;
	}
	/*		/*
	* Skip locked pages during the first two passes to give the		* Skip locked pages during the first two passes to give the
	* functions holding the lock time to release the page. Later we		* functions holding the lock time to release the page. Later we
	* use lock_page() to have a higher chance of acquiring the		* use lock_page() to have a higher chance of acquiring the
	* lock.		* lock.
	*/		*/
			rc = -EAGAIN;
	if (pass > 2)		if (pass > 2)
	lock_page(page);		lock_page(page);
	else		else
	if (TestSetPageLocked(page))		if (TestSetPageLocked(page))
	goto retry_later;		goto next;

	/*		/*
	* Only wait on writeback if we have already done a pass where		* Only wait on writeback if we have already done a pass where
	@@ -713,18 +713,19 @@ int migrate_pages(struct list_head from, struct list_head to,
	if (pass > 0) {		if (pass > 0) {
	wait_on_page_writeback(page);		wait_on_page_writeback(page);
	} else {		} else {
	if (PageWriteback(page)) {		if (PageWriteback(page))
	unlock_page(page);		goto unlock_page;
	goto retry_later;
	}
	}		}

			/*
			* Anonymous pages must have swap cache references otherwise
			* the information contained in the page maps cannot be
			* preserved.
			*/
	if (PageAnon(page) && !PageSwapCache(page)) {		if (PageAnon(page) && !PageSwapCache(page)) {
	if (!add_to_swap(page, GFP_KERNEL)) {		if (!add_to_swap(page, GFP_KERNEL)) {
	unlock_page(page);		rc = -ENOMEM;
	list_move(&page->lru, failed);		goto unlock_page;
	nr_failed++;
	continue;
	}		}
	}		}

	@@ -732,12 +733,23 @@ int migrate_pages(struct list_head from, struct list_head to,
	* Page is properly locked and writeback is complete.		* Page is properly locked and writeback is complete.
	* Try to migrate the page.		* Try to migrate the page.
	*/		*/
	if (!swap_page(page)) {		rc = swap_page(page);
			goto next;

			unlock_page:
			unlock_page(page);

			next:
			if (rc == -EAGAIN) {
			retry++;
			} else if (rc) {
			/* Permanent failure */
			list_move(&page->lru, failed);
			nr_failed++;
			} else {
			/* Success */
	list_move(&page->lru, moved);		list_move(&page->lru, moved);
	continue;
	}		}
	retry_later:
	retry++;
	}		}
	if (retry && pass++ < 10)		if (retry && pass++ < 10)
	goto redo;		goto redo;