From: Michal Nazarewicz mina86@mina86.com
This commit introduces isolate_freepages_range() function which generalises isolate_freepages_block() so that it can be used on arbitrary PFN ranges.
isolate_freepages_block() is left with only minor changes.
Signed-off-by: Michal Nazarewicz mina86@mina86.com Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com Acked-by: Mel Gorman mel@csn.ul.ie Tested-by: Rob Clark rob.clark@linaro.org Tested-by: Ohad Ben-Cohen ohad@wizery.com Tested-by: Benjamin Gaignard benjamin.gaignard@linaro.org --- mm/compaction.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++--------- 1 files changed, 93 insertions(+), 18 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c index 9bbcc53..9fef891 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -54,24 +54,20 @@ static unsigned long release_freepages(struct list_head *freelist) return count; }
-/* Isolate free pages onto a private freelist. Must hold zone->lock */ -static unsigned long isolate_freepages_block(struct zone *zone, - unsigned long blockpfn, - struct list_head *freelist) +/* + * Isolate free pages onto a private freelist. Caller must hold zone->lock. + * If @strict is true, will abort returning 0 on any invalid PFNs or non-free + * pages inside of the pageblock (even though it may still end up isolating + * some pages). + */ +static unsigned long isolate_freepages_block(unsigned long blockpfn, + unsigned long end_pfn, + struct list_head *freelist, + bool strict) { - unsigned long zone_end_pfn, end_pfn; int nr_scanned = 0, total_isolated = 0; struct page *cursor;
- /* Get the last PFN we should scan for free pages at */ - zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages; - end_pfn = min(blockpfn + pageblock_nr_pages, zone_end_pfn); - - /* Find the first usable PFN in the block to initialse page cursor */ - for (; blockpfn < end_pfn; blockpfn++) { - if (pfn_valid_within(blockpfn)) - break; - } cursor = pfn_to_page(blockpfn);
/* Isolate free pages. This assumes the block is valid */ @@ -79,15 +75,23 @@ static unsigned long isolate_freepages_block(struct zone *zone, int isolated, i; struct page *page = cursor;
- if (!pfn_valid_within(blockpfn)) + if (!pfn_valid_within(blockpfn)) { + if (strict) + return 0; continue; + } nr_scanned++;
- if (!PageBuddy(page)) + if (!PageBuddy(page)) { + if (strict) + return 0; continue; + }
/* Found a free page, break it into order-0 pages */ isolated = split_free_page(page); + if (!isolated && strict) + return 0; total_isolated += isolated; for (i = 0; i < isolated; i++) { list_add(&page->lru, freelist); @@ -105,6 +109,73 @@ static unsigned long isolate_freepages_block(struct zone *zone, return total_isolated; }
+/** + * isolate_freepages_range() - isolate free pages. + * @start_pfn: The first PFN to start isolating. + * @end_pfn: The one-past-last PFN. + * + * Non-free pages, invalid PFNs, or zone boundaries within the + * [start_pfn, end_pfn) range are considered errors, cause function to + * undo its actions and return zero. + * + * Otherwise, function returns one-past-the-last PFN of isolated page + * (which may be greater then end_pfn if end fell in a middle of + * a free page). + */ +static unsigned long +isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn) +{ + unsigned long isolated, pfn, block_end_pfn, flags; + struct zone *zone = NULL; + LIST_HEAD(freelist); + + if (pfn_valid(start_pfn)) + zone = page_zone(pfn_to_page(start_pfn)); + + for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) { + if (!pfn_valid(pfn) || zone != page_zone(pfn_to_page(pfn))) + break; + + /* + * On subsequent iterations ALIGN() is actually not needed, + * but we keep it that we not to complicate the code. + */ + block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); + block_end_pfn = min(block_end_pfn, end_pfn); + + spin_lock_irqsave(&zone->lock, flags); + isolated = isolate_freepages_block(pfn, block_end_pfn, + &freelist, true); + spin_unlock_irqrestore(&zone->lock, flags); + + /* + * In strict mode, isolate_freepages_block() returns 0 if + * there are any holes in the block (ie. invalid PFNs or + * non-free pages). + */ + if (!isolated) + break; + + /* + * If we managed to isolate pages, it is always (1 << n) * + * pageblock_nr_pages for some non-negative n. (Max order + * page may span two pageblocks). + */ + } + + /* split_free_page does not map the pages */ + map_pages(&freelist); + + if (pfn < end_pfn) { + /* Loop terminated early, cleanup. */ + release_freepages(&freelist); + return 0; + } + + /* We don't use freelists for anything. */ + return pfn; +} + /* Returns true if the page is within a block suitable for migration to */ static bool suitable_migration_target(struct page *page) { @@ -145,7 +216,7 @@ static void isolate_freepages(struct zone *zone, struct compact_control *cc) { struct page *page; - unsigned long high_pfn, low_pfn, pfn; + unsigned long high_pfn, low_pfn, pfn, zone_end_pfn, end_pfn; unsigned long flags; int nr_freepages = cc->nr_freepages; struct list_head *freelist = &cc->freepages; @@ -165,6 +236,8 @@ static void isolate_freepages(struct zone *zone, */ high_pfn = min(low_pfn, pfn);
+ zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages; + /* * Isolate free pages until enough are available to migrate the * pages on cc->migratepages. We stop searching if the migrate @@ -201,7 +274,9 @@ static void isolate_freepages(struct zone *zone, isolated = 0; spin_lock_irqsave(&zone->lock, flags); if (suitable_migration_target(page)) { - isolated = isolate_freepages_block(zone, pfn, freelist); + end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn); + isolated = isolate_freepages_block(pfn, end_pfn, + freelist, false); nr_freepages += isolated; } spin_unlock_irqrestore(&zone->lock, flags);