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Commit 7039e1db authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Mel Gorman
Browse files

mm: migrate: Introduce migrate_misplaced_page() 



Note: This was originally based on Peter's patch "mm/migrate: Introduce
	migrate_misplaced_page()" but borrows extremely heavily from Andrea's
	"autonuma: memory follows CPU algorithm and task/mm_autonuma stats
	collection". The end result is barely recognisable so signed-offs
	had to be dropped. If original authors are ok with it, I'll
	re-add the signed-off-bys.

Add migrate_misplaced_page() which deals with migrating pages from
faults.

Based-on-work-by: default avatarLee Schermerhorn <Lee.Schermerhorn@hp.com>
Based-on-work-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Based-on-work-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
parent 771fb4d8

include/linux/migrate.h

+11 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ enum migrate_reason { 
	MR_MEMORY_HOTPLUG,

	MR_SYSCALL,		/* also applies to cpusets */

	MR_MEMPOLICY_MBIND,

	MR_NUMA_MISPLACED,

	MR_CMA

};
@@ -73,4 +74,14 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping, 
#define fail_migrate_page NULL



#endif /* CONFIG_MIGRATION */



#ifdef CONFIG_NUMA_BALANCING

extern int migrate_misplaced_page(struct page *page, int node);

#else

static inline int migrate_misplaced_page(struct page *page, int node)

{

	return -EAGAIN; /* can't migrate now */

}

#endif /* CONFIG_NUMA_BALANCING */



#endif /* _LINUX_MIGRATE_H */

mm/migrate.c

+106 −2
Original line number Diff line number Diff line
@@ -282,7 +282,7 @@ static int migrate_page_move_mapping(struct address_space *mapping, 
		struct page *newpage, struct page *page,

		struct buffer_head *head, enum migrate_mode mode)

{

	int expected_count;

	int expected_count = 0;

	void **pslot;



	if (!mapping) {
@@ -1415,4 +1415,108 @@ int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, 
 	}

 	return err;

}

#endif
 


#ifdef CONFIG_NUMA_BALANCING

/*

 * Returns true if this is a safe migration target node for misplaced NUMA

 * pages. Currently it only checks the watermarks which crude

 */

static bool migrate_balanced_pgdat(struct pglist_data *pgdat,

				   int nr_migrate_pages)

{

	int z;

	for (z = pgdat->nr_zones - 1; z >= 0; z--) {

		struct zone *zone = pgdat->node_zones + z;



		if (!populated_zone(zone))

			continue;



		if (zone->all_unreclaimable)

			continue;



		/* Avoid waking kswapd by allocating pages_to_migrate pages. */

		if (!zone_watermark_ok(zone, 0,

				       high_wmark_pages(zone) +

				       nr_migrate_pages,

				       0, 0))

			continue;

		return true;

	}

	return false;

}



static struct page *alloc_misplaced_dst_page(struct page *page,

					   unsigned long data,

					   int **result)

{

	int nid = (int) data;

	struct page *newpage;



	newpage = alloc_pages_exact_node(nid,

					 (GFP_HIGHUSER_MOVABLE | GFP_THISNODE |

					  __GFP_NOMEMALLOC | __GFP_NORETRY |

					  __GFP_NOWARN) &

					 ~GFP_IOFS, 0);

	return newpage;

}



/*

 * Attempt to migrate a misplaced page to the specified destination

 * node. Caller is expected to have an elevated reference count on

 * the page that will be dropped by this function before returning.

 */

int migrate_misplaced_page(struct page *page, int node)

{

	int isolated = 0;

	LIST_HEAD(migratepages);



	/*

	 * Don't migrate pages that are mapped in multiple processes.

	 * TODO: Handle false sharing detection instead of this hammer

	 */

	if (page_mapcount(page) != 1) {

		put_page(page);

		goto out;

	}



	/* Avoid migrating to a node that is nearly full */

	if (migrate_balanced_pgdat(NODE_DATA(node), 1)) {

		int page_lru;



		if (isolate_lru_page(page)) {

			put_page(page);

			goto out;

		}

		isolated = 1;



		/*

		 * Page is isolated which takes a reference count so now the

		 * callers reference can be safely dropped without the page

		 * disappearing underneath us during migration

		 */

		put_page(page);



		page_lru = page_is_file_cache(page);

		inc_zone_page_state(page, NR_ISOLATED_ANON + page_lru);

		list_add(&page->lru, &migratepages);

	}



	if (isolated) {

		int nr_remaining;



		nr_remaining = migrate_pages(&migratepages,

				alloc_misplaced_dst_page,

				node, false, MIGRATE_ASYNC,

				MR_NUMA_MISPLACED);

		if (nr_remaining) {

			putback_lru_pages(&migratepages);

			isolated = 0;

		}

	}

	BUG_ON(!list_empty(&migratepages));

out:

	return isolated;

}

#endif /* CONFIG_NUMA_BALANCING */



#endif /* CONFIG_NUMA */