Commit c8244935 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm: compaction: make isolate_lru_page() filter-aware again 



Commit 39deaf85 ("mm: compaction: make isolate_lru_page() filter-aware")
noted that compaction does not migrate dirty or writeback pages and that
is was meaningless to pick the page and re-add it to the LRU list.  This
had to be partially reverted because some dirty pages can be migrated by
compaction without blocking.

This patch updates "mm: compaction: make isolate_lru_page" by skipping
over pages that migration has no possibility of migrating to minimise LRU
disruption.

Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Reviewed-by: default avatarRik van <Riel&lt;riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b969c4ab

include/linux/mmzone.h

+2 −0
Original line number Diff line number Diff line
@@ -177,6 +177,8 @@ struct lruvec { 
#define ISOLATE_CLEAN		((__force isolate_mode_t)0x4)

/* Isolate unmapped file */

#define ISOLATE_UNMAPPED	((__force isolate_mode_t)0x8)

/* Isolate for asynchronous migration */

#define ISOLATE_ASYNC_MIGRATE	((__force isolate_mode_t)0x10)



/* LRU Isolation modes. */

typedef unsigned __bitwise__ isolate_mode_t;

mm/compaction.c

+3 −0
Original line number Diff line number Diff line
@@ -349,6 +349,9 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, 
			continue;

		}



		if (!cc->sync)

			mode |= ISOLATE_ASYNC_MIGRATE;



		/* Try isolate the page */

		if (__isolate_lru_page(page, mode, 0) != 0)

			continue;

mm/vmscan.c

+33 −2
Original line number Diff line number Diff line
@@ -1075,9 +1075,40 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file) 


	ret = -EBUSY;



	if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page)))

	/*

	 * To minimise LRU disruption, the caller can indicate that it only

	 * wants to isolate pages it will be able to operate on without

	 * blocking - clean pages for the most part.

	 *

	 * ISOLATE_CLEAN means that only clean pages should be isolated. This

	 * is used by reclaim when it is cannot write to backing storage

	 *

	 * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages

	 * that it is possible to migrate without blocking

	 */

	if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) {

		/* All the caller can do on PageWriteback is block */

		if (PageWriteback(page))

			return ret;



		if (PageDirty(page)) {

			struct address_space *mapping;



			/* ISOLATE_CLEAN means only clean pages */

			if (mode & ISOLATE_CLEAN)

				return ret;



			/*

			 * Only pages without mappings or that have a

			 * ->migratepage callback are possible to migrate

			 * without blocking

			 */

			mapping = page_mapping(page);

			if (mapping && !mapping->a_ops->migratepage)

				return ret;

		}

	}



	if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))

		return ret;

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