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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43d6f4bf2b4sm12414218f8f.20.2026.04.12.15.50.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Apr 2026 15:51:00 -0700 (PDT) Date: Sun, 12 Apr 2026 18:50:57 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Andrew Morton , David Hildenbrand , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , linux-mm@kvack.org, virtualization@lists.linux.dev, Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang Subject: [PATCH RFC 6/9] mm: skip zeroing in vma_alloc_anon_folio_pmd for pre-zeroed pages Message-ID: <7287019f2665c85a7a7fb5ffc25d7203bdfa9a9c.1776033771.git.mst@redhat.com> References: MIME-Version: 1.0 In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: c4SJT684gTcNJNdR8caQ1dtHyTOoAg8Hd_SFJA06Hak_1776034261 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Queue-Id: A86D140009 X-Stat-Signature: fd5sxszhes77dxypbibpxf66xyuo8r66 X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1776034264-231860 X-HE-Meta: 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 5B5zqBzl ubldAaVeklbRtrctsVB/YObatBbgD67drQ00lI+vFkqizTWdk7jQUwGta9Q2yvfOMLlZ4rzF8VEkpK8WJsdiBKqgmAIT0xvh3NLQjmdwGnyB75UzHy/OMx4jVXGYKS2Rq3vIhlZrTSw2WPXULYihYk0l10gDEvwfZvt5NzXyjBh0o05Fdjcugd9l2mXys5BhadW1rhPNDVrDKhITKuVzIxtc0WVFqrmRuQ4EQXnETGeiHPCOWTeTW4/5qkyTpqCZT3purTmB+EkJHL7xc14C1tHUN5NRcIb+hOreKyFIoge+Mo6cYCLtSQCY8NbSLkFuj5yqkvZMMjozVSLY4RPnkyL+OhmSytNdKkHkGSK1BhNQvrsQYXDJB8raTlw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Use __GFP_PREZEROED and folio_test_clear_prezeroed() to skip folio_zero_user() in the PMD THP anonymous page allocation path when the page is already zeroed. Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 --- mm/huge_memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8e2746ea74ad..3b9b53fad0f1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1256,7 +1256,7 @@ EXPORT_SYMBOL_GPL(thp_get_unmapped_area); static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, unsigned long addr) { - gfp_t gfp = vma_thp_gfp_mask(vma); + gfp_t gfp = vma_thp_gfp_mask(vma) | __GFP_PREZEROED; const int order = HPAGE_PMD_ORDER; struct folio *folio; @@ -1285,7 +1285,7 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, * make sure that the page corresponding to the faulting address will be * hot in the cache after zeroing. */ - if (user_alloc_needs_zeroing()) + if (user_alloc_needs_zeroing() && !folio_test_clear_prezeroed(folio)) folio_zero_user(folio, addr); /* * The memory barrier inside __folio_mark_uptodate makes sure that -- MST