4.4-stable review patch. If anyone has any objections, please let me know.
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From: Joonsoo Kim iamjoonsoo.kim@lge.com
commit e1409c325fdc1fef7b3d8025c51892355f065d15 upstream.
pageblock_pfn_to_page() is used to check there is valid pfn and all pages in the pageblock is in a single zone. If there is a hole in the pageblock, passing arbitrary position to pageblock_pfn_to_page() could cause to skip whole pageblock scanning, instead of just skipping the hole page. For deterministic behaviour, it's better to always pass pageblock aligned range to pageblock_pfn_to_page(). It will also help further optimization on pageblock_pfn_to_page() in the following patch.
Signed-off-by: Joonsoo Kim iamjoonsoo.kim@lge.com Cc: Aaron Lu aaron.lu@intel.com Cc: David Rientjes rientjes@google.com Cc: Mel Gorman mgorman@suse.de Cc: Rik van Riel riel@redhat.com Acked-by: Vlastimil Babka vbabka@suse.cz Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Mel Gorman mgorman@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- mm/compaction.c | 41 ++++++++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 11 deletions(-)
--- a/mm/compaction.c +++ b/mm/compaction.c @@ -553,13 +553,17 @@ unsigned long isolate_freepages_range(struct compact_control *cc, unsigned long start_pfn, unsigned long end_pfn) { - unsigned long isolated, pfn, block_end_pfn; + unsigned long isolated, pfn, block_start_pfn, block_end_pfn; LIST_HEAD(freelist);
pfn = start_pfn; + block_start_pfn = pfn & ~(pageblock_nr_pages - 1); + if (block_start_pfn < cc->zone->zone_start_pfn) + block_start_pfn = cc->zone->zone_start_pfn; block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
for (; pfn < end_pfn; pfn += isolated, + block_start_pfn = block_end_pfn, block_end_pfn += pageblock_nr_pages) { /* Protect pfn from changing by isolate_freepages_block */ unsigned long isolate_start_pfn = pfn; @@ -572,11 +576,13 @@ isolate_freepages_range(struct compact_c * scanning range to right one. */ if (pfn >= block_end_pfn) { + block_start_pfn = pfn & ~(pageblock_nr_pages - 1); 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)) + if (!pageblock_pfn_to_page(block_start_pfn, + block_end_pfn, cc->zone)) break;
isolated = isolate_freepages_block(cc, &isolate_start_pfn, @@ -862,18 +868,23 @@ unsigned long isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn, unsigned long end_pfn) { - unsigned long pfn, block_end_pfn; + unsigned long pfn, block_start_pfn, block_end_pfn;
/* Scan block by block. First and last block may be incomplete */ pfn = start_pfn; + block_start_pfn = pfn & ~(pageblock_nr_pages - 1); + if (block_start_pfn < cc->zone->zone_start_pfn) + block_start_pfn = cc->zone->zone_start_pfn; block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
for (; pfn < end_pfn; pfn = block_end_pfn, + block_start_pfn = block_end_pfn, block_end_pfn += pageblock_nr_pages) {
block_end_pfn = min(block_end_pfn, end_pfn);
- if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone)) + if (!pageblock_pfn_to_page(block_start_pfn, + block_end_pfn, cc->zone)) continue;
pfn = isolate_migratepages_block(cc, pfn, block_end_pfn, @@ -1091,7 +1102,9 @@ int sysctl_compact_unevictable_allowed _ static isolate_migrate_t isolate_migratepages(struct zone *zone, struct compact_control *cc) { - unsigned long low_pfn, end_pfn; + unsigned long block_start_pfn; + unsigned long block_end_pfn; + unsigned long low_pfn; unsigned long isolate_start_pfn; struct page *page; const isolate_mode_t isolate_mode = @@ -1103,16 +1116,21 @@ static isolate_migrate_t isolate_migrate * initialized by compact_zone() */ low_pfn = cc->migrate_pfn; + block_start_pfn = cc->migrate_pfn & ~(pageblock_nr_pages - 1); + if (block_start_pfn < zone->zone_start_pfn) + block_start_pfn = zone->zone_start_pfn;
/* Only scan within a pageblock boundary */ - end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages); + block_end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
/* * Iterate over whole pageblocks until we find the first suitable. * Do not cross the free scanner. */ - for (; end_pfn <= cc->free_pfn; - low_pfn = end_pfn, end_pfn += pageblock_nr_pages) { + for (; block_end_pfn <= cc->free_pfn; + low_pfn = block_end_pfn, + block_start_pfn = block_end_pfn, + block_end_pfn += pageblock_nr_pages) {
/* * This can potentially iterate a massively long zone with @@ -1123,7 +1141,8 @@ static isolate_migrate_t isolate_migrate && compact_should_abort(cc)) break;
- page = pageblock_pfn_to_page(low_pfn, end_pfn, zone); + page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, + zone); if (!page) continue;
@@ -1142,8 +1161,8 @@ static isolate_migrate_t isolate_migrate
/* Perform the isolation */ isolate_start_pfn = low_pfn; - low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn, - isolate_mode); + low_pfn = isolate_migratepages_block(cc, low_pfn, + block_end_pfn, isolate_mode);
if (!low_pfn || cc->contended) { acct_isolated(zone, cc);