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Mon, 07 Jul 2025 14:51:06 -0400 X-MC-Unique: puodWzYmPnWtPJi8IF8K7w-1 X-Mimecast-MFC-AGG-ID: puodWzYmPnWtPJi8IF8K7w_1751914265 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AE6A619560A6; Mon, 7 Jul 2025 18:51:04 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.80.96]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 3B03A19560AB; Mon, 7 Jul 2025 18:51:03 +0000 (UTC) From: Luiz Capitulino To: david@redhat.com, willy@infradead.org, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, shivankg@amd.com, sj@kernel.org Subject: [PATCH v2 1/4] mm/memory: introduce is_huge_zero_pfn() and use it in vm_normal_page_pmd() Date: Mon, 7 Jul 2025 14:50:43 -0400 Message-ID: <0e343f6f088fc79f625161b5d74567d696f2228e.1751914235.git.luizcap@redhat.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 X-Rspam-User: X-Rspamd-Queue-Id: 6460E80011 X-Rspamd-Server: rspam09 X-Stat-Signature: n8at1tmcjhkiehzyu7ohuh5zagqsu9kp X-HE-Tag: 1751914270-54019 X-HE-Meta: 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 YYbG4MnE UaJbYNd55CCuvNMrzXVu/0ypM4j/N3FoRRSlbvrrKjTCHPZ92QFq5Am7WcdMHCQqUkISHwYB+Iy4woOhwIiDPj/xdSzZSnL0n1Tl+5BeLWAyA7slsVByJFhrw2pg8c4N3jYB9SYsGh4JsVDTnkzQdLRoHaaxQLvLNIzYesvGrFDyYrb7DxUpgczaXwu6uNgUhxqACCEMVCpVOS3uOxCRB/yMRdpCcPfygdGFB9PvXzyw0zFDdeZwvsAPlqBIZnuJrR+wO8P0OJisOzGAjWAu8TSavGQgNKLdl+kqnzJVsv+1hmWDsXFDmAxCZNVdzGCJfd7VNN1tZJwvxFbTk+iblsp9wQQyUgZtIFf+W2M64lkluxPbHiaPxCx7PHjyFc1sRBuOBpeh6LbfJiMJUu7ByZFQwTWEU3qBo01jM X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: David Hildenbrand Let's avoid working with the PMD when not required. If vm_normal_page_pmd() would be called on something that is not a present pmd, it would already be a bug (pfn possibly garbage). While at it, let's support passing in any pfn covered by the huge zero folio by masking off PFN bits -- which should be rather cheap. Signed-off-by: David Hildenbrand Reviewed-by: Oscar Salvador Signed-off-by: Luiz Capitulino --- include/linux/huge_mm.h | 12 +++++++++++- mm/memory.c | 2 +- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 2f190c90192d..59e93fba15f4 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -486,9 +486,14 @@ static inline bool is_huge_zero_folio(const struct folio *folio) return READ_ONCE(huge_zero_folio) == folio; } +static inline bool is_huge_zero_pfn(unsigned long pfn) +{ + return READ_ONCE(huge_zero_pfn) == (pfn & ~(HPAGE_PMD_NR - 1)); +} + static inline bool is_huge_zero_pmd(pmd_t pmd) { - return pmd_present(pmd) && READ_ONCE(huge_zero_pfn) == pmd_pfn(pmd); + return pmd_present(pmd) && is_huge_zero_pfn(pmd_pfn(pmd)); } struct folio *mm_get_huge_zero_folio(struct mm_struct *mm); @@ -636,6 +641,11 @@ static inline bool is_huge_zero_folio(const struct folio *folio) return false; } +static inline bool is_huge_zero_pfn(unsigned long pfn) +{ + return false; +} + static inline bool is_huge_zero_pmd(pmd_t pmd) { return false; diff --git a/mm/memory.c b/mm/memory.c index b0cda5aab398..3a765553bacb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -687,7 +687,7 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, if (pmd_devmap(pmd)) return NULL; - if (is_huge_zero_pmd(pmd)) + if (is_huge_zero_pfn(pfn)) return NULL; if (unlikely(pfn > highest_memmap_pfn)) return NULL; -- 2.50.0