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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43d63dec27fsm27061714f8f.11.2026.04.12.15.50.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Apr 2026 15:50:52 -0700 (PDT) Date: Sun, 12 Apr 2026 18:50:50 -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 , "Liam R. Howlett" , Mike Rapoport Subject: [PATCH RFC 4/9] mm: skip zeroing in vma_alloc_zeroed_movable_folio for pre-zeroed pages Message-ID: <027a31beac698f90e76aa68ba6a6101ba60246d0.1776033771.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: oHaWrfr8Vd-Q7AHV7t07cL53RnKRlhMG5rEnr9R32j4_1776034255 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Stat-Signature: pqmnpz7zkdqu6bkn6kdzzmaoimkf389f X-Rspamd-Queue-Id: 25BB0C000C X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1776034257-900910 X-HE-Meta: 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 4UuAypDs bbFL5t4SGj9Kr36M2x9A/44BLJCKiHg6ZXhvfoBvAY6uALgdpcmz8biVxqe7GxFOfIh+ijd5jD++3+E7EV9BaHEXqF/yeUbt6i7bf5GMQmsOdps7PG9IZ8lB8wo5MuwoOc8wPYelVuJ8BRa8UxveWIp8Y2sZ8v8AQEH780oorGOEpETkfZZ2MbAWivEnGgG6sS2fRAvWxf3YhkxwPaCkhcPjWhRhN1C3zHfmwx8YigO3/zjcketHzeEf+uzvQdnlaJxxVBiaowUzW9sPoLd2p5dm7bGxOHMBjGQ3y6nz8VBkGnHPabb+h9oZ6gYtW/XNQ9k92eySQc7kS3h2KNsRakZxdL8/K1lfrWBaWWDbgvb2b5sVCTOJoCRMHAg== 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 clear_user_highpage() when the page is already zeroed. On x86, vma_alloc_zeroed_movable_folio is overridden by a macro that uses __GFP_ZERO directly, so this change has no effect there. Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 --- include/linux/highmem.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index af03db851a1d..b649e7e315f4 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -322,8 +322,10 @@ struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, { struct folio *folio; - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); - if (folio && user_alloc_needs_zeroing()) + folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_PREZEROED, + 0, vma, vaddr); + if (folio && user_alloc_needs_zeroing() && + !folio_test_clear_prezeroed(folio)) clear_user_highpage(&folio->page, vaddr); return folio; -- MST