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Commit 5c3f9a67 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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mm: page migration remove_migration_ptes at lock+unlock level 



Clean up page migration a little more by calling remove_migration_ptes()
from the same level, on success or on failure, from __unmap_and_move() or
from unmap_and_move_huge_page().

Don't reset page->mapping of a PageAnon old page in move_to_new_page(),
leave that to when the page is freed.  Except for here in page migration,
it has been an invariant that a PageAnon (bit set in page->mapping) page
stays PageAnon until it is freed, and I think we're safer to keep to that.

And with the above rearrangement, it's necessary because zap_pte_range()
wants to identify whether a migration entry represents a file or an anon
page, to update the appropriate rss stats without waiting on it.

Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7db7671f

mm/migrate.c

+19 −15
Original line number Diff line number Diff line
@@ -722,7 +722,7 @@ static int fallback_migrate_page(struct address_space *mapping, 
 *  MIGRATEPAGE_SUCCESS - success

 */

static int move_to_new_page(struct page *newpage, struct page *page,

				int page_was_mapped, enum migrate_mode mode)

				enum migrate_mode mode)

{

	struct address_space *mapping;

	int rc;
@@ -755,19 +755,21 @@ static int move_to_new_page(struct page *newpage, struct page *page, 
		 * space which also has its own migratepage callback. This

		 * is the most common path for page migration.

		 */

		rc = mapping->a_ops->migratepage(mapping,

						newpage, page, mode);

		rc = mapping->a_ops->migratepage(mapping, newpage, page, mode);

	else

		rc = fallback_migrate_page(mapping, newpage, page, mode);



	if (rc != MIGRATEPAGE_SUCCESS) {

		set_page_memcg(newpage, NULL);

		newpage->mapping = NULL;

	} else {

	/*

	 * When successful, old pagecache page->mapping must be cleared before

	 * page is freed; but stats require that PageAnon be left as PageAnon.

	 */

	if (rc == MIGRATEPAGE_SUCCESS) {

		set_page_memcg(page, NULL);

		if (page_was_mapped)

			remove_migration_ptes(page, newpage);

		if (!PageAnon(page))

			page->mapping = NULL;

	} else {

		set_page_memcg(newpage, NULL);

		newpage->mapping = NULL;

	}

	return rc;

}
@@ -902,10 +904,11 @@ static int __unmap_and_move(struct page *page, struct page *newpage, 
	}



	if (!page_mapped(page))

		rc = move_to_new_page(newpage, page, page_was_mapped, mode);

		rc = move_to_new_page(newpage, page, mode);



	if (rc && page_was_mapped)

		remove_migration_ptes(page, page);

	if (page_was_mapped)

		remove_migration_ptes(page,

			rc == MIGRATEPAGE_SUCCESS ? newpage : page);



out_unlock_both:

	unlock_page(newpage);
@@ -1066,10 +1069,11 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, 
	}



	if (!page_mapped(hpage))

		rc = move_to_new_page(new_hpage, hpage, page_was_mapped, mode);

		rc = move_to_new_page(new_hpage, hpage, mode);



	if (rc != MIGRATEPAGE_SUCCESS && page_was_mapped)

		remove_migration_ptes(hpage, hpage);

	if (page_was_mapped)

		remove_migration_ptes(hpage,

			rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage);



	unlock_page(new_hpage);