In fast_isolate_around(), it assumes the pageblock is fully scanned if cc->nr_freepages < cc->nr_migratepages after trying to isolate some free pages, and will set skip flag to avoid scanning in future. However this can miss setting the skip flag for a fully scanned pageblock (returned 'start_pfn' is equal to 'end_pfn') in the case where cc->nr_freepages is larger than cc->nr_migratepages. So using the returned 'start_pfn' from isolate_freepages_block() and 'end_pfn' to decide if a pageblock is fully scanned makes more sense. It can also cover the case where cc->nr_freepages < cc->nr_migratepages, which means the 'start_pfn' is usually equal to 'end_pfn' except some uncommon fatal error occurs after non-strict mode isolation. Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index 3737c6591bfb..1e5183f39ca9 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1411,7 +1411,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn) isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false); /* Skip this pageblock in the future as it's full or nearly full */ - if (cc->nr_freepages < cc->nr_migratepages) + if (start_pfn == end_pfn) set_pageblock_skip(page); return; -- 2.27.0
