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From:   Doug Berger <opendmb@gmail.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Jonathan Corbet <corbet@lwn.net>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
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        Borislav Petkov <bp@suse.de>,
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        Randy Dunlap <rdunlap@infradead.org>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Doug Berger <opendmb@gmail.com>,
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        - <devicetree-spec@vger.kernel.org>,
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        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-mm@kvack.org, iommu@lists.linux.dev
Subject: [PATCH 06/21] mm/hugetlb: add hugepage isolation support
Date:   Tue, 13 Sep 2022 12:54:53 -0700
Message-Id: <20220913195508.3511038-7-opendmb@gmail.com>
In-Reply-To: <20220913195508.3511038-1-opendmb@gmail.com>
References: <20220913195508.3511038-1-opendmb@gmail.com>
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When a range of pageblocks is isolated there is at most one
hugepage that has only tail pages overlapping that range (i.e.
a hugepage that overlaps the beginning of the range).

However, that hugepage is the first migration target for an
alloc_contig_range() attempt so it already receives special
attention.

Checking whether the pageblock containing the head of a hugepage
is isolated is an inexpensive way to avoid hugepage allocations
from isolated pageblocks which makes alloc_contig_range() more
efficient.

Signed-off-by: Doug Berger <opendmb@gmail.com>
---
 mm/hugetlb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index da80889e1436..2f354423f50f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -33,6 +33,7 @@
 #include <linux/migrate.h>
 #include <linux/nospec.h>
 #include <linux/delayacct.h>
+#include <linux/page-isolation.h>
 
 #include <asm/page.h>
 #include <asm/pgalloc.h>
@@ -1135,6 +1136,10 @@ static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
 		if (PageHWPoison(page))
 			continue;
 
+		/* Check head pageblock isolation */
+		if (is_migrate_isolate_page(page))
+			continue;
+
 		list_move(&page->lru, &h->hugepage_activelist);
 		set_page_refcounted(page);
 		ClearHPageFreed(page);
-- 
2.25.1