linux-kernel - [RFC PATCH v2 3/7] mm: migrate: allocate the right size of non hugetlb or THP compound pages.

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Message-Id: <20211209230414.2766515-4-zi.yan@sent.com>
Date:   Thu,  9 Dec 2021 18:04:10 -0500
From:   Zi Yan <zi.yan@...t.com>
To:     David Hildenbrand <david@...hat.com>, linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        linuxppc-dev@...ts.ozlabs.org,
        virtualization@...ts.linux-foundation.org,
        iommu@...ts.linux-foundation.org, Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Eric Ren <renzhengeek@...il.com>, Zi Yan <ziy@...dia.com>
Subject: [RFC PATCH v2 3/7] mm: migrate: allocate the right size of non hugetlb or THP compound pages.

From: Zi Yan <ziy@...dia.com>

alloc_migration_target() is used by alloc_contig_range() and non-LRU
movable compound pages can be migrated. Current code does not allocate the
right page size for such pages. Check THP precisely using
is_transparent_huge() and add allocation support for non-LRU compound
pages.

Signed-off-by: Zi Yan <ziy@...dia.com>
---
 mm/migrate.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index d487a399253b..2ce3c771b1de 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1563,7 +1563,7 @@ struct page *alloc_migration_target(struct page *page, unsigned long private)
 		return alloc_huge_page_nodemask(h, nid, mtc->nmask, gfp_mask);
 	}
 
-	if (PageTransHuge(page)) {
+	if (is_transparent_hugepage(page)) {
 		/*
 		 * clear __GFP_RECLAIM to make the migration callback
 		 * consistent with regular THP allocations.
@@ -1572,13 +1572,17 @@ struct page *alloc_migration_target(struct page *page, unsigned long private)
 		gfp_mask |= GFP_TRANSHUGE;
 		order = HPAGE_PMD_ORDER;
 	}
+	if (PageCompound(page)) {
+		gfp_mask |= __GFP_COMP;
+		order = compound_order(page);
+	}
 	zidx = zone_idx(page_zone(page));
 	if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
 		gfp_mask |= __GFP_HIGHMEM;
 
 	new_page = __alloc_pages(gfp_mask, order, nid, mtc->nmask);
 
-	if (new_page && PageTransHuge(new_page))
+	if (new_page && is_transparent_hugepage(page))
 		prep_transhuge_page(new_page);
 
 	return new_page;
-- 
2.33.0