From:   Zi Yan <zi.yan@sent.com>
To:     David Hildenbrand <david@redhat.com>, linux-mm@kvack.org
Cc:     linux-kernel@vger.kernel.org,
        Michael Ellerman <mpe@ellerman.id.au>,
        Christoph Hellwig <hch@lst.de>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Robin Murphy <robin.murphy@arm.com>,
        linuxppc-dev@lists.ozlabs.org,
        virtualization@lists.linux-foundation.org,
        iommu@lists.linux-foundation.org, Vlastimil Babka <vbabka@suse.cz>,
        Mel Gorman <mgorman@techsingularity.net>,
        Eric Ren <renzhengeek@gmail.com>, Zi Yan <ziy@nvidia.com>
Subject: [RFC PATCH v3 3/8] mm: migrate: allocate the right size of non hugetlb or THP compound pages.
Date:   Wed,  5 Jan 2022 16:47:51 -0500
Message-Id: <20220105214756.91065-4-zi.yan@sent.com>
In-Reply-To: <20220105214756.91065-1-zi.yan@sent.com>
References: <20220105214756.91065-1-zi.yan@sent.com>
Reply-To: Zi Yan <ziy@nvidia.com>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
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From: Zi Yan <ziy@nvidia.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@nvidia.com>
---
 mm/migrate.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index c7da064b4781..b1851ffb8576 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1546,9 +1546,7 @@ struct page *alloc_migration_target(struct page *page=
, unsigned long private)
=20
 		gfp_mask =3D htlb_modify_alloc_mask(h, gfp_mask);
 		return alloc_huge_page_nodemask(h, nid, mtc->nmask, gfp_mask);
-	}
-
-	if (PageTransHuge(page)) {
+	} else if (is_transparent_hugepage(page)) {
 		/*
 		 * clear __GFP_RECLAIM to make the migration callback
 		 * consistent with regular THP allocations.
@@ -1556,14 +1554,19 @@ struct page *alloc_migration_target(struct page *pa=
ge, unsigned long private)
 		gfp_mask &=3D ~__GFP_RECLAIM;
 		gfp_mask |=3D GFP_TRANSHUGE;
 		order =3D HPAGE_PMD_ORDER;
+	} else if (PageCompound(page)) {
+		/* for non-LRU movable compound pages */
+		gfp_mask |=3D __GFP_COMP;
+		order =3D compound_order(page);
 	}
+
 	zidx =3D zone_idx(page_zone(page));
 	if (is_highmem_idx(zidx) || zidx =3D=3D ZONE_MOVABLE)
 		gfp_mask |=3D __GFP_HIGHMEM;
=20
 	new_page =3D __alloc_pages(gfp_mask, order, nid, mtc->nmask);
=20
-	if (new_page && PageTransHuge(new_page))
+	if (new_page && is_transparent_hugepage(page))
 		prep_transhuge_page(new_page);
=20
 	return new_page;
--=20
2.34.1