diff options
| -rw-r--r-- | mm/compaction.c | 91 |
1 files changed, 57 insertions, 34 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index 8058e3f98f08..1067c07cb33d 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -67,6 +67,49 @@ static inline bool migrate_async_suitable(int migratetype) return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE; } +/* + * Check that the whole (or subset of) a pageblock given by the interval of + * [start_pfn, end_pfn) is valid and within the same zone, before scanning it + * with the migration of free compaction scanner. The scanners then need to + * use only pfn_valid_within() check for arches that allow holes within + * pageblocks. + * + * Return struct page pointer of start_pfn, or NULL if checks were not passed. + * + * It's possible on some configurations to have a setup like node0 node1 node0 + * i.e. it's possible that all pages within a zones range of pages do not + * belong to a single zone. We assume that a border between node0 and node1 + * can occur within a single pageblock, but not a node0 node1 node0 + * interleaving within a single pageblock. It is therefore sufficient to check + * the first and last page of a pageblock and avoid checking each individual + * page in a pageblock. + */ +static struct page *pageblock_pfn_to_page(unsigned long start_pfn, + unsigned long end_pfn, struct zone *zone) +{ + struct page *start_page; + struct page *end_page; + + /* end_pfn is one past the range we are checking */ + end_pfn--; + + if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn)) + return NULL; + + start_page = pfn_to_page(start_pfn); + + if (page_zone(start_page) != zone) + return NULL; + + end_page = pfn_to_page(end_pfn); + + /* This gives a shorter code than deriving page_zone(end_page) */ + if (page_zone_id(start_page) != page_zone_id(end_page)) + return NULL; + + return start_page; +} + #ifdef CONFIG_COMPACTION /* Returns true if the pageblock should be scanned for pages to isolate. */ static inline bool isolation_suitable(struct compact_control *cc, @@ -371,17 +414,17 @@ isolate_freepages_range(struct compact_control *cc, unsigned long isolated, pfn, block_end_pfn; LIST_HEAD(freelist); - for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) { - if (!pfn_valid(pfn) || cc->zone != page_zone(pfn_to_page(pfn))) - break; + pfn = start_pfn; + block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); + + for (; pfn < end_pfn; pfn += isolated, + block_end_pfn += pageblock_nr_pages) { - /* - * 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); + if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone)) + break; + isolated = isolate_freepages_block(cc, pfn, block_end_pfn, &freelist, true); @@ -507,15 +550,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, continue; nr_scanned++; - /* - * Get the page and ensure the page is within the same zone. - * See the comment in isolate_freepages about overlapping - * nodes. It is deliberate that the new zone lock is not taken - * as memory compaction should not move pages between nodes. - */ page = pfn_to_page(low_pfn); - if (page_zone(page) != zone) - continue; if (!valid_page) valid_page = page; @@ -653,8 +688,7 @@ isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn, block_end_pfn = min(block_end_pfn, end_pfn); - /* Skip whole pageblock in case of a memory hole */ - if (!pfn_valid(pfn)) + if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone)) continue; pfn = isolate_migratepages_block(cc, pfn, block_end_pfn, @@ -727,18 +761,9 @@ static void isolate_freepages(struct compact_control *cc) && compact_should_abort(cc)) break; - if (!pfn_valid(block_start_pfn)) - continue; - - /* - * Check for overlapping nodes/zones. It's possible on some - * configurations to have a setup like - * node0 node1 node0 - * i.e. it's possible that all pages within a zones range of - * pages do not belong to a single zone. - */ - page = pfn_to_page(block_start_pfn); - if (page_zone(page) != zone) + page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, + zone); + if (!page) continue; /* Check the block is suitable for migration */ @@ -873,12 +898,10 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, && compact_should_abort(cc)) break; - /* Skip whole pageblock in case of a memory hole */ - if (!pfn_valid(low_pfn)) + page = pageblock_pfn_to_page(low_pfn, end_pfn, zone); + if (!page) continue; - page = pfn_to_page(low_pfn); - /* If isolation recently failed, do not retry */ if (!isolation_suitable(cc, page)) continue; |