Commit 89eb946a authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

mm: Convert page migration to XArray 



Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
parent 560d454b

mm/migrate.c

+18 −30
Original line number Diff line number Diff line
@@ -323,7 +323,7 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, 
	page = migration_entry_to_page(entry);



	/*

	 * Once radix-tree replacement of page migration started, page_count

	 * Once page cache replacement of page migration started, page_count

	 * *must* be zero. And, we don't want to call wait_on_page_locked()

	 * against a page without get_page().

	 * So, we use get_page_unless_zero(), here. Even failed, page fault
@@ -438,10 +438,10 @@ int migrate_page_move_mapping(struct address_space *mapping, 
		struct buffer_head *head, enum migrate_mode mode,

		int extra_count)

{

	XA_STATE(xas, &mapping->i_pages, page_index(page));

	struct zone *oldzone, *newzone;

	int dirty;

	int expected_count = 1 + extra_count;

	void **pslot;



	/*

	 * Device public or private pages have an extra refcount as they are
@@ -467,21 +467,16 @@ int migrate_page_move_mapping(struct address_space *mapping, 
	oldzone = page_zone(page);

	newzone = page_zone(newpage);



	xa_lock_irq(&mapping->i_pages);



	pslot = radix_tree_lookup_slot(&mapping->i_pages,

 					page_index(page));

	xas_lock_irq(&xas);



	expected_count += hpage_nr_pages(page) + page_has_private(page);

	if (page_count(page) != expected_count ||

		radix_tree_deref_slot_protected(pslot,

					&mapping->i_pages.xa_lock) != page) {

		xa_unlock_irq(&mapping->i_pages);

	if (page_count(page) != expected_count || xas_load(&xas) != page) {

		xas_unlock_irq(&xas);

		return -EAGAIN;

	}



	if (!page_ref_freeze(page, expected_count)) {

		xa_unlock_irq(&mapping->i_pages);

		xas_unlock_irq(&xas);

		return -EAGAIN;

	}
@@ -495,7 +490,7 @@ int migrate_page_move_mapping(struct address_space *mapping, 
	if (mode == MIGRATE_ASYNC && head &&

			!buffer_migrate_lock_buffers(head, mode)) {

		page_ref_unfreeze(page, expected_count);

		xa_unlock_irq(&mapping->i_pages);

		xas_unlock_irq(&xas);

		return -EAGAIN;

	}
@@ -523,16 +518,13 @@ int migrate_page_move_mapping(struct address_space *mapping, 
		SetPageDirty(newpage);

	}



	radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);

	xas_store(&xas, newpage);

	if (PageTransHuge(page)) {

		int i;

		int index = page_index(page);



		for (i = 1; i < HPAGE_PMD_NR; i++) {

			pslot = radix_tree_lookup_slot(&mapping->i_pages,

						       index + i);

			radix_tree_replace_slot(&mapping->i_pages, pslot,

						newpage + i);

			xas_next(&xas);

			xas_store(&xas, newpage + i);

		}

	}
@@ -543,7 +535,7 @@ int migrate_page_move_mapping(struct address_space *mapping, 
	 */

	page_ref_unfreeze(page, expected_count - hpage_nr_pages(page));



	xa_unlock(&mapping->i_pages);

	xas_unlock(&xas);

	/* Leave irq disabled to prevent preemption while updating stats */



	/*
@@ -583,22 +575,18 @@ EXPORT_SYMBOL(migrate_page_move_mapping); 
int migrate_huge_page_move_mapping(struct address_space *mapping,

				   struct page *newpage, struct page *page)

{

	XA_STATE(xas, &mapping->i_pages, page_index(page));

	int expected_count;

	void **pslot;



	xa_lock_irq(&mapping->i_pages);



	pslot = radix_tree_lookup_slot(&mapping->i_pages, page_index(page));



	xas_lock_irq(&xas);

	expected_count = 2 + page_has_private(page);

	if (page_count(page) != expected_count ||

		radix_tree_deref_slot_protected(pslot, &mapping->i_pages.xa_lock) != page) {

		xa_unlock_irq(&mapping->i_pages);

	if (page_count(page) != expected_count || xas_load(&xas) != page) {

		xas_unlock_irq(&xas);

		return -EAGAIN;

	}



	if (!page_ref_freeze(page, expected_count)) {

		xa_unlock_irq(&mapping->i_pages);

		xas_unlock_irq(&xas);

		return -EAGAIN;

	}
@@ -607,11 +595,11 @@ int migrate_huge_page_move_mapping(struct address_space *mapping, 


	get_page(newpage);



	radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);

	xas_store(&xas, newpage);



	page_ref_unfreeze(page, expected_count - 1);



	xa_unlock_irq(&mapping->i_pages);

	xas_unlock_irq(&xas);



	return MIGRATEPAGE_SUCCESS;

}