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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4890009e759sm216401175e9.6.2026.04.20.05.50.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 05:50:52 -0700 (PDT) Date: Mon, 20 Apr 2026 08:50:49 -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 v2 11/18] mm: skip zeroing in vma_alloc_zeroed_movable_folio for pre-zeroed pages Message-ID: <39c3c8e647fc4c8e3dcb5c9d12f2e29b5404e8f2.1776689093.git.mst@redhat.com> References: Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: 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: 2YIVl2ikG8yxoaXfKQkIyFyW24nNj7Xt5Zgw35TJkmE_1776689453 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Use vma_alloc_folio_hints() and check PGHINT_ZEROED 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 Assisted-by: cursor-agent:GPT-5.4-xhigh --- 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..8bb67772c1cb 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -321,9 +321,11 @@ struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, unsigned long vaddr) { struct folio *folio; + pghint_t hints; - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); - if (folio && user_alloc_needs_zeroing()) + folio = vma_alloc_folio_hints(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr, + &hints); + if (folio && user_alloc_needs_zeroing() && !(hints & PGHINT_ZEROED)) clear_user_highpage(&folio->page, vaddr); return folio; -- MST