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Mon, 14 Jul 2025 09:17:12 -0400 X-MC-Unique: X42RbnBUM9mJmbfIthzxuw-1 X-Mimecast-MFC-AGG-ID: X42RbnBUM9mJmbfIthzxuw_1752499030 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 540BA1801210; Mon, 14 Jul 2025 13:17:10 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.80.96]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9041F18002B5; Mon, 14 Jul 2025 13:17:08 +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, harry.yoo@oracle.com Subject: [PATCH v3 1/4] mm/memory: introduce is_huge_zero_pfn() and use it in vm_normal_page_pmd() Date: Mon, 14 Jul 2025 09:16:51 -0400 Message-ID: <4940826e99f0c709a7cf7beb94f53288320aea5a.1752499009.git.luizcap@redhat.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Rspamd-Queue-Id: E80E4A0008 X-Stat-Signature: s5yeorcynhpn79idskykchmsw5yn4ako X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1752499035-839111 X-HE-Meta: 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 Svob6Qhc 5i0P5uLaM+Zh2r6icrDQBrQC0QfSk6IpAmtGFhQHRoGJF2YDn7ydhxrGZskksQw+EsVdEd/H//dJkAU3X7HGi48KJflv0cdaGhql0/IQfedcOhNacKBMmYzFt3Himm9o+GAO8wZ97E1h1diut6pvFnmtLr2v8K8eGC2U8sszueSYl0NF3RaiGIdmjtP2mAo0sLDPHQci2SG5fXVx9qXwylpblRXASBgLdJojB3NIZl1TCCjpfUC6tdOsn9C/n0lrDHNjzX6arSMCXQ/26erEUzG3DLWwv3Fb356wHhv+gN6apuCwAZ4EqepVGIslfQh50mf2MzHTSavp4zON002TFI+runX9P0KNzqKyxc0GHcGWLTCUMiWzxJxWzbPGdRIQBGi35YPFCczw2x86bgR/qbjw14CWkRlfzFXWK 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