Commit 64c8902e authored by Huang Ying's avatar Huang Ying Committed by Andrew Morton
Browse files

migrate_pages: split unmap_and_move() to _unmap() and _move() 

This is a preparation patch to batch the folio unmapping and moving.

In this patch, unmap_and_move() is split to migrate_folio_unmap() and
migrate_folio_move().  So, we can batch _unmap() and _move() in different
loops later.  To pass some information between unmap and move, the
original unused dst->mapping and dst->private are used.

Link: https://lkml.kernel.org/r/20230213123444.155149-5-ying.huang@intel.com


Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Reviewed-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: default avatarXin Hao <xhao@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Bharata B Rao <bharata@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 42012e04

include/linux/migrate.h

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ struct migration_target_control; 
 * - zero on page migration success;

 */

#define MIGRATEPAGE_SUCCESS		0

#define MIGRATEPAGE_UNMAP		1



/**

 * struct movable_operations - Driver page migration

mm/migrate.c

+128 −41
Original line number Diff line number Diff line
@@ -1027,11 +1027,53 @@ static int move_to_new_folio(struct folio *dst, struct folio *src, 
	return rc;

}



static int __unmap_and_move(struct folio *src, struct folio *dst,

/*

 * To record some information during migration, we use some unused

 * fields (mapping and private) of struct folio of the newly allocated

 * destination folio.  This is safe because nobody is using them

 * except us.

 */

static void __migrate_folio_record(struct folio *dst,

				   unsigned long page_was_mapped,

				   struct anon_vma *anon_vma)

{

	dst->mapping = (void *)anon_vma;

	dst->private = (void *)page_was_mapped;

}



static void __migrate_folio_extract(struct folio *dst,

				   int *page_was_mappedp,

				   struct anon_vma **anon_vmap)

{

	*anon_vmap = (void *)dst->mapping;

	*page_was_mappedp = (unsigned long)dst->private;

	dst->mapping = NULL;

	dst->private = NULL;

}



/* Cleanup src folio upon migration success */

static void migrate_folio_done(struct folio *src,

			       enum migrate_reason reason)

{

	/*

	 * Compaction can migrate also non-LRU pages which are

	 * not accounted to NR_ISOLATED_*. They can be recognized

	 * as __PageMovable

	 */

	if (likely(!__folio_test_movable(src)))

		mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +

				    folio_is_file_lru(src), -folio_nr_pages(src));



	if (reason != MR_MEMORY_FAILURE)

		/* We release the page in page_handle_poison. */

		folio_put(src);

}



static int __migrate_folio_unmap(struct folio *src, struct folio *dst,

				int force, enum migrate_mode mode)

{

	int rc = -EAGAIN;

	bool page_was_mapped = false;

	int page_was_mapped = 0;

	struct anon_vma *anon_vma = NULL;

	bool is_lru = !__PageMovable(&src->page);
@@ -1107,8 +1149,8 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, 
		goto out_unlock;



	if (unlikely(!is_lru)) {

		rc = move_to_new_folio(dst, src, mode);

		goto out_unlock_both;

		__migrate_folio_record(dst, page_was_mapped, anon_vma);

		return MIGRATEPAGE_UNMAP;

	}



	/*
@@ -1133,11 +1175,42 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, 
		VM_BUG_ON_FOLIO(folio_test_anon(src) &&

			       !folio_test_ksm(src) && !anon_vma, src);

		try_to_migrate(src, 0);

		page_was_mapped = true;

		page_was_mapped = 1;

	}



	if (!folio_mapped(src))

	if (!folio_mapped(src)) {

		__migrate_folio_record(dst, page_was_mapped, anon_vma);

		return MIGRATEPAGE_UNMAP;

	}



	if (page_was_mapped)

		remove_migration_ptes(src, src, false);



out_unlock_both:

	folio_unlock(dst);

out_unlock:

	/* Drop an anon_vma reference if we took one */

	if (anon_vma)

		put_anon_vma(anon_vma);

	folio_unlock(src);

out:



	return rc;

}



static int __migrate_folio_move(struct folio *src, struct folio *dst,

				enum migrate_mode mode)

{

	int rc;

	int page_was_mapped = 0;

	struct anon_vma *anon_vma = NULL;

	bool is_lru = !__PageMovable(&src->page);



	__migrate_folio_extract(dst, &page_was_mapped, &anon_vma);



	rc = move_to_new_folio(dst, src, mode);

	if (unlikely(!is_lru))

		goto out_unlock_both;



	/*

	 * When successful, push dst to LRU immediately: so that if it
@@ -1160,12 +1233,10 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, 


out_unlock_both:

	folio_unlock(dst);

out_unlock:

	/* Drop an anon_vma reference if we took one */

	if (anon_vma)

		put_anon_vma(anon_vma);

	folio_unlock(src);

out:

	/*

	 * If migration is successful, decrease refcount of dst,

	 * which will not free the page because new page owner increased
@@ -1177,19 +1248,15 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, 
	return rc;

}



/*

 * Obtain the lock on folio, remove all ptes and migrate the folio

 * to the newly allocated folio in dst.

 */

static int unmap_and_move(new_page_t get_new_page,

				   free_page_t put_new_page,

/* Obtain the lock on page, remove all ptes. */

static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page,

			       unsigned long private, struct folio *src,

				   int force, enum migrate_mode mode,

				   enum migrate_reason reason,

			       struct folio **dstp, int force,

			       enum migrate_mode mode, enum migrate_reason reason,

			       struct list_head *ret)

{

	struct folio *dst;

	int rc = MIGRATEPAGE_SUCCESS;

	int rc = MIGRATEPAGE_UNMAP;

	struct page *newpage = NULL;



	if (!thp_migration_supported() && folio_test_transhuge(src))
@@ -1200,20 +1267,49 @@ static int unmap_and_move(new_page_t get_new_page, 
		folio_clear_active(src);

		folio_clear_unevictable(src);

		/* free_pages_prepare() will clear PG_isolated. */

		goto out;

		list_del(&src->lru);

		migrate_folio_done(src, reason);

		return MIGRATEPAGE_SUCCESS;

	}



	newpage = get_new_page(&src->page, private);

	if (!newpage)

		return -ENOMEM;

	dst = page_folio(newpage);

	*dstp = dst;



	dst->private = NULL;

	rc = __unmap_and_move(src, dst, force, mode);

	rc = __migrate_folio_unmap(src, dst, force, mode);

	if (rc == MIGRATEPAGE_UNMAP)

		return rc;



	/*

	 * A folio that has not been unmapped will be restored to

	 * right list unless we want to retry.

	 */

	if (rc != -EAGAIN)

		list_move_tail(&src->lru, ret);



	if (put_new_page)

		put_new_page(&dst->page, private);

	else

		folio_put(dst);



	return rc;

}



/* Migrate the folio to the newly allocated folio in dst. */

static int migrate_folio_move(free_page_t put_new_page, unsigned long private,

			      struct folio *src, struct folio *dst,

			      enum migrate_mode mode, enum migrate_reason reason,

			      struct list_head *ret)

{

	int rc;



	rc = __migrate_folio_move(src, dst, mode);

	if (rc == MIGRATEPAGE_SUCCESS)

		set_page_owner_migrate_reason(&dst->page, reason);



out:

	if (rc != -EAGAIN) {

		/*

		 * A folio that has been migrated has all references
@@ -1229,20 +1325,7 @@ static int unmap_and_move(new_page_t get_new_page, 
	 * we want to retry.

	 */

	if (rc == MIGRATEPAGE_SUCCESS) {

		/*

		 * Compaction can migrate also non-LRU folios which are

		 * not accounted to NR_ISOLATED_*. They can be recognized

		 * as __folio_test_movable

		 */

		if (likely(!__folio_test_movable(src)))

			mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +

					folio_is_file_lru(src), -folio_nr_pages(src));



		if (reason != MR_MEMORY_FAILURE)

			/*

			 * We release the folio in page_handle_poison.

			 */

			folio_put(src);

		migrate_folio_done(src, reason);

	} else {

		if (rc != -EAGAIN)

			list_add_tail(&src->lru, ret);
@@ -1534,7 +1617,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, 
	int pass = 0;

	bool is_large = false;

	bool is_thp = false;

	struct folio *folio, *folio2;

	struct folio *folio, *folio2, *dst = NULL;

	int rc, nr_pages;

	LIST_HEAD(split_folios);

	bool nosplit = (reason == MR_NUMA_MISPLACED);
@@ -1561,8 +1644,12 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, 


			cond_resched();



			rc = unmap_and_move(get_new_page, put_new_page,

					    private, folio, pass > 2, mode,

			rc = migrate_folio_unmap(get_new_page, put_new_page, private,

						 folio, &dst, pass > 2, mode,

						 reason, ret_folios);

			if (rc == MIGRATEPAGE_UNMAP)

				rc = migrate_folio_move(put_new_page, private,

							folio, dst, mode,

							reason, ret_folios);

			/*

			 * The rules are: