Date:   Sat, 18 Feb 2023 00:27:49 +0000
In-Reply-To: <20230218002819.1486479-1-jthoughton@google.com>
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Message-ID: <20230218002819.1486479-17-jthoughton@google.com>
Subject: [PATCH v2 16/46] hugetlb: make default arch_make_huge_pte understand
 small mappings
From:   James Houghton <jthoughton@google.com>
To:     Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Peter Xu <peterx@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     David Hildenbrand <david@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Mina Almasry <almasrymina@google.com>,
        "Zach O'Keefe" <zokeefe@google.com>,
        Manish Mishra <manish.mishra@nutanix.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Baolin Wang <baolin.wang@linux.alibaba.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Yang Shi <shy828301@gmail.com>,
        Frank van der Linden <fvdl@google.com>,
        Jiaqi Yan <jiaqiyan@google.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        James Houghton <jthoughton@google.com>
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Precedence: bulk

This is a simple change: don't create a "huge" PTE if we are making a
regular, PAGE_SIZE PTE. All architectures that want to implement HGM
likely need to be changed in a similar way if they implement their own
version of arch_make_huge_pte.

Signed-off-by: James Houghton <jthoughton@google.com>

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 726d581158b1..b767b6889dea 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -899,7 +899,7 @@ static inline void arch_clear_hugepage_flags(struct page *page) { }
 static inline pte_t arch_make_huge_pte(pte_t entry, unsigned int shift,
 				       vm_flags_t flags)
 {
-	return pte_mkhuge(entry);
+	return shift > PAGE_SHIFT ? pte_mkhuge(entry) : entry;
 }
 #endif
 
-- 
2.39.2.637.g21b0678d19-goog