isolate_freepages() is currently somewhat hard to follow thanks to many different pfn variables. Especially misleading is the name 'high_pfn' which looks like it is related to the 'low_pfn' variable, but in fact it is not.
This patch renames the 'high_pfn' variable to a hopefully less confusing name, and slightly changes its handling without a functional change. A comment made obsolete by recent changes is also updated. Signed-off-by: Vlastimil Babka <[email protected]> Cc: Minchan Kim <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Bartlomiej Zolnierkiewicz <[email protected]> Cc: Michal Nazarewicz <[email protected]> Cc: Naoya Horiguchi <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Rik van Riel <[email protected]> --- mm/compaction.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 627dc2e..169c7b2 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -671,7 +671,7 @@ static void isolate_freepages(struct zone *zone, struct compact_control *cc) { struct page *page; - unsigned long high_pfn, low_pfn, pfn, z_end_pfn; + unsigned long pfn, low_pfn, next_free_pfn, z_end_pfn; int nr_freepages = cc->nr_freepages; struct list_head *freelist = &cc->freepages; @@ -688,11 +688,10 @@ static void isolate_freepages(struct zone *zone, low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages); /* - * Take care that if the migration scanner is at the end of the zone - * that the free scanner does not accidentally move to the next zone - * in the next isolation cycle. + * Seed the value for max(next_free_pfn, pfn) updates. If there are + * none, the pfn < low_pfn check will kick in. */ - high_pfn = min(low_pfn, pfn); + next_free_pfn = 0; z_end_pfn = zone_end_pfn(zone); @@ -754,7 +753,7 @@ static void isolate_freepages(struct zone *zone, */ if (isolated) { cc->finished_update_free = true; - high_pfn = max(high_pfn, pfn); + next_free_pfn = max(next_free_pfn, pfn); } } @@ -766,9 +765,9 @@ static void isolate_freepages(struct zone *zone, * so that compact_finished() may detect this */ if (pfn < low_pfn) - cc->free_pfn = max(pfn, zone->zone_start_pfn); - else - cc->free_pfn = high_pfn; + next_free_pfn = max(pfn, zone->zone_start_pfn); + + cc->free_pfn = next_free_pfn; cc->nr_freepages = nr_freepages; } -- 1.8.4.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
