Commit c2135f7c authored by Alex Shi's avatar Alex Shi Committed by Linus Torvalds
Browse files

mm/vmscan: __isolate_lru_page_prepare() cleanup 

The function just returns 2 results, so using a 'switch' to deal with its
result is unnecessary.  Also simplify it to a bool func as Vlastimil
suggested.

Also remove 'goto' by reusing list_move(), and take Matthew Wilcox's
suggestion to update comments in function.

Link: https://lkml.kernel.org/r/728874d7-2d93-4049-68c1-dcc3b2d52ccd@linux.alibaba.com


Signed-off-by: default avatarAlex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7ecc9565

include/linux/swap.h

+1 −1
Original line number Diff line number Diff line
@@ -356,7 +356,7 @@ extern void lru_cache_add_inactive_or_unevictable(struct page *page, 
extern unsigned long zone_reclaimable_pages(struct zone *zone);

extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,

					gfp_t gfp_mask, nodemask_t *mask);

extern int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode);

extern bool __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode);

extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,

						  unsigned long nr_pages,

						  gfp_t gfp_mask,

mm/compaction.c

+1 −1
Original line number Diff line number Diff line
@@ -988,7 +988,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, 
		if (unlikely(!get_page_unless_zero(page)))

			goto isolate_fail;



		if (__isolate_lru_page_prepare(page, isolate_mode) != 0)

		if (!__isolate_lru_page_prepare(page, isolate_mode))

			goto isolate_fail_put;



		/* Try isolate the page */

mm/vmscan.c

+31 −37
Original line number Diff line number Diff line
@@ -1539,19 +1539,17 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, 
 * page:	page to consider

 * mode:	one of the LRU isolation modes defined above

 *

 * returns 0 on success, -ve errno on failure.

 * returns true on success, false on failure.

 */

int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode)

bool __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode)

{

	int ret = -EBUSY;



	/* Only take pages on the LRU. */

	if (!PageLRU(page))

		return ret;

		return false;



	/* Compaction should not handle unevictable pages but CMA can do so */

	if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE))

		return ret;

		return false;



	/*

	 * To minimise LRU disruption, the caller can indicate that it only
@@ -1564,7 +1562,7 @@ int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode) 
	if (mode & ISOLATE_ASYNC_MIGRATE) {

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

		if (PageWriteback(page))

			return ret;

			return false;



		if (PageDirty(page)) {

			struct address_space *mapping;
@@ -1580,20 +1578,20 @@ int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode) 
			 * from the page cache.

			 */

			if (!trylock_page(page))

				return ret;

				return false;



			mapping = page_mapping(page);

			migrate_dirty = !mapping || mapping->a_ops->migratepage;

			unlock_page(page);

			if (!migrate_dirty)

				return ret;

				return false;

		}

	}



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

		return ret;

		return false;



	return 0;

	return true;

}



/*
@@ -1677,35 +1675,31 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, 
		 * only when the page is being freed somewhere else.

		 */

		scan += nr_pages;

		switch (__isolate_lru_page_prepare(page, mode)) {

		case 0:

		if (!__isolate_lru_page_prepare(page, mode)) {

			/* It is being freed elsewhere */

			list_move(&page->lru, src);

			continue;

		}

		/*

		 * Be careful not to clear PageLRU until after we're

		 * sure the page is not being freed elsewhere -- the

		 * page release code relies on it.

		 */

			if (unlikely(!get_page_unless_zero(page)))

				goto busy;

		if (unlikely(!get_page_unless_zero(page))) {

			list_move(&page->lru, src);

			continue;

		}



		if (!TestClearPageLRU(page)) {

				/*

				 * This page may in other isolation path,

				 * but we still hold lru_lock.

				 */

			/* Another thread is already isolating this page */

			put_page(page);

				goto busy;

			list_move(&page->lru, src);

			continue;

		}



		nr_taken += nr_pages;

		nr_zone_taken[page_zonenum(page)] += nr_pages;

		list_move(&page->lru, dst);

			break;



		default:

busy:

			/* else it is being freed elsewhere */

			list_move(&page->lru, src);

		}

	}



	/*