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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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        Randy Dunlap <rdunlap@infradead.org>,
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        linux-mm@kvack.org, iommu@lists.linux.dev
Subject: [PATCH 02/21] mm/hugetlb: correct max_huge_pages accounting on demote
Date:   Tue, 13 Sep 2022 12:54:49 -0700
Message-Id: <20220913195508.3511038-3-opendmb@gmail.com>
In-Reply-To: <20220913195508.3511038-1-opendmb@gmail.com>
References: <20220913195508.3511038-1-opendmb@gmail.com>
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When demoting a hugepage to a smaller order, the number of pages
added to the target hstate will be the size of the large page
divided by the size of the smaller page.

Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support")
Signed-off-by: Doug Berger <opendmb@gmail.com>
---
 mm/hugetlb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e070b8593b37..79949893ac12 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3472,7 +3472,8 @@ static int demote_free_huge_page(struct hstate *h, struct page *page)
 	 * based on pool changes for the demoted page.
 	 */
 	h->max_huge_pages--;
-	target_hstate->max_huge_pages += pages_per_huge_page(h);
+	target_hstate->max_huge_pages += pages_per_huge_page(h) /
+					 pages_per_huge_page(target_hstate);
 
 	return rc;
 }
-- 
2.25.1