From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6D44C337BBD for ; Sun, 12 Apr 2026 22:51:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776034262; cv=none; b=rm2IVlWfX/DcKpKOHJvowSNoYmYsO7pFrZ22c2jfjQGcxbPD8u18m4WgVatqWYIPMgZW9fBANBxNOH2sf7z10c8qY75mSvER0ItuvCoPVWTNqKON3aZOZEceGzD4KXTGGgZS9gbOjJV+YDW1rrpyLCvPZgSsOFRnZ+inJoqG6tk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776034262; c=relaxed/simple; bh=6gjSNaFIDSNyW8+yvCTZyht2lyKWhv9QbxmNHAkjjAY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: In-Reply-To:Content-Type:Content-Disposition; b=P5p/Vl/OIX4hxDRxLG0C1k7LH/yPVujEZ1DCfdOVdEoZLl6fKVQ0PzPkVevJBEy+HfFVMWtCCtxbC8HSTJNgULUyWQd86xMt6iRkcOMp9jurP9C7yP41GfQhSVSjfHFOlr40ofCsu/PChsObhdROAe/Gz1demYhRtNicia6r21M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=HvMhdOti; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HvMhdOti" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1776034260; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZObZy/vetFZ/0CGX/0sKWeCj7TXTkOR8AcV2oS2lySk=; b=HvMhdOtibyxBwhAWHaNAFk3A6aBGnH/GzAku+k13qfIPXWWrFxxd6xPEQXzlOcmTQPyyQb BV8TRHzxYkSwWzdbf/hCNVXOJxfCWPlx2t0f54LexKCFugm9clGyG1aWKAvD676rfWjA66 NOYkxl2XlWx1zlBZ4kecp6ADBn5E9/o= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-564-VRXn1ImgOyqza0w7jvfbBA-1; Sun, 12 Apr 2026 18:50:59 -0400 X-MC-Unique: VRXn1ImgOyqza0w7jvfbBA-1 X-Mimecast-MFC-AGG-ID: VRXn1ImgOyqza0w7jvfbBA_1776034258 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-43d7730e9e3so219828f8f.2 for ; Sun, 12 Apr 2026 15:50:59 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776034258; x=1776639058; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ZObZy/vetFZ/0CGX/0sKWeCj7TXTkOR8AcV2oS2lySk=; b=DzS81aThzBsPe3YakpNB/hcsj/2CMUhycq3UgFgIDES8GhuKXKAZg+JWVeLOb2nzzH TG/aRPLgczsnvdnnFPzM+YAqpWGh1284XltRLlNRh9TZ/roiE/vuar+o6jLdOTXOcbP/ WCaEZ3Ci2u6g5p0ZtPwuSdMioHpAOErasVoWfagBIeXB+LHhsG3/L+5YNar5w2ey12bz sI/nLqBIYiV7E/ff4B9BO1c/UNO+XmcmNlyv8Lrk4ZPlPUivLnHpO5op3FmQSFhQTHMn supvbt4fluINdWST5iaThk42o8lWvyhmh4OqAsCa+U4nUfJqTIWAolbNYc5aqM9WuTam pQAw== X-Forwarded-Encrypted: i=1; AFNElJ/Ist34FSSeDObgM1lHfW6s0HrT1Ivsp5nYn6OaElEYJYlFoEsu0+xfXR815DXRmVEeepIW4H5rJIXmlmbOCw==@lists.linux.dev X-Gm-Message-State: AOJu0YwHTQgCrSmGaX+lWm+1b6ArTjztMnwUwUDnFb+ZNpTjJGZYeKTc v4nHwyP5bCPUkaxtfio3j+NE+J0dJ8c+U7SJzepq835KTF+AwXidUFumbsyGSoQ2xTwaITRlp6h LmiWCBBDnIOii3wD5EeOD0Csk0U0K30WEpX4Z5VsMONiP+2Exl/yptD24KrD0ytQjf13v X-Gm-Gg: AeBDietPY2r4nHDzfkX+4+scDh4FNKwxiE8eFV7ibBZ6plxCNgMYuDGXtjiaiuogoFv 5br8CzVdZ4sA7fbANn2/GwGjhJjHUysH7d++yQOpIv+8sssRhdD4Uby4IPviKCpKYPXmnm7WaCF ptdQ9LNmumC8sMrdBVNmRgEaQAKuXvnZE0mTBpG2S4JdgiZ134K79w4aVOrpxmGI6QicNtNy7uy 1Wmy8gXYaG87N2mWatYvuDgawbbSoj6hXhm8Ac5hw/R39DvG0dlQG7wzT671ZPiNWP5uBTXo9qO 21FG/0Q2MJIV5tPXC1ftUE7hbbdwfnEzVk/Eq9QZb4xAeArNbSkBFm3qPu6UJ+ro4MXOEGOBbKz aY2dGdv+BspOK5+bEEo+fn7eq27SGXBzLWhNF275PkfM= X-Received: by 2002:a05:6000:250f:b0:43d:1c7a:8b5b with SMTP id ffacd0b85a97d-43d642d1d00mr16517168f8f.40.1776034258050; Sun, 12 Apr 2026 15:50:58 -0700 (PDT) X-Received: by 2002:a05:6000:250f:b0:43d:1c7a:8b5b with SMTP id ffacd0b85a97d-43d642d1d00mr16517133f8f.40.1776034257540; Sun, 12 Apr 2026 15:50:57 -0700 (PDT) Received: from redhat.com (IGLD-80-230-25-21.inter.net.il. [80.230.25.21]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43d7400708dsm9145343f8f.25.2026.04.12.15.50.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Apr 2026 15:50:56 -0700 (PDT) Date: Sun, 12 Apr 2026 18:50:54 -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 5/9] mm: skip zeroing in alloc_anon_folio for pre-zeroed pages Message-ID: <56ae30d7f080b089e4fdc93c4d6e2353a9e0123a.1776033771.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: wZjdu3k0OHg83OQdQeKNzcV-vDKxVtXsO2SZivcwEqY_1776034258 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Use __GFP_PREZEROED and folio_test_clear_prezeroed() to skip folio_zero_user() in the mTHP anonymous page allocation path when the page is already zeroed. Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 --- mm/memory.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 07778814b4a8..2f61321a81fd 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5176,7 +5176,7 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf) goto fallback; /* Try allocating the highest of the remaining orders. */ - gfp = vma_thp_gfp_mask(vma); + gfp = vma_thp_gfp_mask(vma) | __GFP_PREZEROED; while (orders) { addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order); folio = vma_alloc_folio(gfp, order, vma, addr); @@ -5194,7 +5194,8 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf) * 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, vmf->address); return folio; } -- MST