From: Baolin Wang baolin.wang@linux.alibaba.com
mainline inclusion from mainline-v6.9-rc1 commit 1883e8ac96ddd73a87db7f2f8c06111148a3db6f category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CXS6 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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It can not improve the fragmentation if we isolate the target free pages exceeding cc->order, especially when the cc->order is less than pageblock_order. For example, suppose the pageblock_order is MAX_ORDER (size is 4M) and cc->order is 2M THP size, we should not isolate other 2M free pages to be the migration target, which can not improve the fragmentation.
Moreover this is also applicable for large folio compaction.
Link: https://lkml.kernel.org/r/afcd9377351c259df7a25a388a4a0d5862b986f4.170592839... Signed-off-by: Baolin Wang baolin.wang@linux.alibaba.com Acked-by: Mel Gorman mgorman@techsingularity.net Cc: Vlastimil Babka vbabka@suse.cz Cc: Zi Yan ziy@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/compaction.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/compaction.c b/mm/compaction.c index 923c9a480ea8..1a2ddc1e1a91 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1347,12 +1347,14 @@ static bool suitable_migration_target(struct compact_control *cc, { /* If the page is a large free page, then disallow migration */ if (PageBuddy(page)) { + int order = cc->order > 0 ? cc->order : pageblock_order; + /* * We are checking page_order without zone->lock taken. But * the only small danger is that we skip a potentially suitable * pageblock, so it's not worth to check order for valid range. */ - if (buddy_order_unsafe(page) >= pageblock_order) + if (buddy_order_unsafe(page) >= order) return false; }