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 9D9A5438FEF for ; Fri, 29 May 2026 15:25:23 +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=1780068324; cv=none; b=InmozmVF53ZAUk7ATGUwgCbwYtOtFi3tyfd07zZo016wM736gVX3BWR//kXH7MhnMQWNGnfqthPAO7F09IwkGisMt3jc3C/f/rK3rMhmWx1VYCsQmNJFRJJqcjHQmszqaEYsmI5SDxChPFpMIgP573kPrYpVwRhCGlROoyMmCfA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780068324; c=relaxed/simple; bh=V5Y93H57q2xi9ZVdVLl8OLD+jeqpAWNwQzgfVZDhJj0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iIvjptdMoogN4ZG91hsnK7uGsmN2cdyBAoRvSuef0eByFlnHWKTlSd5+OTxvull9RS5jtRAvCwwtgAepSQ3yXZl7XpTNq026kCeoMPcQN/ZanPcQff3RaK1fE9mC2ieC81Ewy1Ihhbj0hvdyZRNB1xhR2eD6EoYCTdDbsFZOnoc= 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=AGIKh9vf; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=q0JWnCIX; 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="AGIKh9vf"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="q0JWnCIX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1780068322; 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=lR7ppjC8ZhT95gw1LzQhYf3JteDpTHqAJsB6tR6PXLg=; b=AGIKh9vfNI+zXMnouUkf+y0a58gOQnT3SFhUZLxdR8nuxQMUk5ODB+aNBEor1LmX3kpsbP Tz9nTaXZBpAEwnO4b8jio/tXvO2fxbJyXZAEVwsWyptMeMqdMe50ja64VqtFdSZt9nhpbi sJNuGsY+hAOiXQivQitqSw+wdF4+h70= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-382-SgwH1iOcO2maaiRVKzn3qw-1; Fri, 29 May 2026 11:25:21 -0400 X-MC-Unique: SgwH1iOcO2maaiRVKzn3qw-1 X-Mimecast-MFC-AGG-ID: SgwH1iOcO2maaiRVKzn3qw_1780068320 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-49047e9ca88so63694475e9.3 for ; Fri, 29 May 2026 08:25:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1780068320; x=1780673120; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=lR7ppjC8ZhT95gw1LzQhYf3JteDpTHqAJsB6tR6PXLg=; b=q0JWnCIX1jFA6K1B93VRFexRrcglnTmFZETuGPyWuocUxPbiMPhHOvf7UYiDS6fIDi dkmKV/GJ+fzn2kXpL4m6t4aWRAXPKg+1Du/+kVCThKr/U8xOYsmQpkkPCY5WruwHPrqF mpDxUa/BfdtSWTXnj6WxP3Iv9iVWkaD5Uwl9IsZxFeqzAhnKwYhh+3iSE3dMcpSgZx8i XMsH0czKUB6ZjlQTtzrIxoHnB/nRGakTI/YCBzjMzfxKanS2lA2eM6+c49L2PqfVY77V 7QliuzGzHLeTPq98CJkHropwZoGcYA8tSbLJxMDEJhnGndLUtICr0CXllhTv2C04SVNE hMiw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780068320; x=1780673120; 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=lR7ppjC8ZhT95gw1LzQhYf3JteDpTHqAJsB6tR6PXLg=; b=VI6QARfoxx1FfuxpTHX91YSsUFCDLIeqgVUCmALCGncml1uh0wIzmOKLTXMZB4W+1W 1dPr3fGpNH/GuLVMdh8tLZp7AlbfrUpTA2aDAokAZwC4PaMdEG0UHI4xginVCnNicrk4 dLfaJrtsPoC9qI+rwhLUOz9R7Ch1MlG++f8ArmyuDWRkrRA3+g2uU7nM41xMypxzDxjJ WECDFI1LCMJ2VFOLcIQf+sr+Y/cMXm5W3Dm7LALfV3CFiJSrnkhAcTKItX9tI5RNpw7K SA6CkqJdtry3zrE6UDlbTHXwkljjVpLElexECBsGq9nLKQ9A5fiF/RYMjsnnBW2TzcLp EKzw== X-Gm-Message-State: AOJu0Ywecj2HSvJcO3nS/7S189hw9w7C0ou85u+qYYP71HIr/AohWUDu SzAGjyNg3xFl6MyxXMc0eXH2MTIxAAxmhkWmkNDPal48c83EQdqaMoURGsHCLQkc4ZfdsqMGGpU /mDvr1mVlXaZBemtQZiq6Is92nXZLkDyusZXw1ivj0z9/henEKJnDG0vz/Egof0KdclL2GH7jbQ uaRwjQwO7PozWfYiLeyGSO0C4w4NSPOvOO8FHaVboHrU0= X-Gm-Gg: Acq92OFeoNMUy7YGd35H8U9/n+UDdXtsaas7raVYrnDiOCRfK6yEMD4lEe0qXxoa1Ya DXHnKeirafYgQhJREOXIfSbi0Ma7afhmE2x2eG48Fv+b1pXaVyt8egExTHhch5eHYDsz4Z9As19 M7yD4aR8YiIXCwribzDpy8CPIu72kdwRZFyjwFapexHaqags7uUZqlnIT5CkIfxaU1twAi0oEaj nKw5ksxeMfS/KLjSJPSd045CqiEQRgYbP94LDjD1eu7/pd83yqXDqXdwO1LHiN9Np58Q4PM9HkP A4z6r6vWbWeZpnC+KdDlsMPuUwdO2UulA6Xh0JnsUA7aIzHYkae7/6axdNtRTiOaCIK70Wi2cC2 P2Sqra6TAR/PXwaV1q2vvJ9O7YdXyLI0dEKpwv+NAIZKz+LdEvgFgDA== X-Received: by 2002:a05:600c:c3c1:20b0:490:9d1b:2022 with SMTP id 5b1f17b1804b1-490a2938ad2mr1299495e9.13.1780068319886; Fri, 29 May 2026 08:25:19 -0700 (PDT) X-Received: by 2002:a05:600c:c3c1:20b0:490:9d1b:2022 with SMTP id 5b1f17b1804b1-490a2938ad2mr1298395e9.13.1780068319303; Fri, 29 May 2026 08:25:19 -0700 (PDT) Received: from redhat.com (IGLD-80-230-25-45.inter.net.il. [80.230.25.45]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490a25e4fe7sm7967095e9.0.2026.05.29.08.25.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 May 2026 08:25:18 -0700 (PDT) Date: Fri, 29 May 2026 11:25:14 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: "David Hildenbrand (Arm)" , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , Muchun Song , Oscar Salvador , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Hugh Dickins , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Axel Rasmussen , Yuanchu Xie , Wei Xu , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , virtualization@lists.linux.dev, linux-mm@kvack.org, Andrea Arcangeli Subject: [PATCH v9 34/37] mm: page_alloc: skip kernel_init_pages for FPI_ZEROED when safe Message-ID: <5c9d3afebc53d21cd13feb05b27f503f367d46b2.1780067978.git.mst@redhat.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent In __free_pages_prepare(), when FPI_ZEROED is set the page is already known to be zero. We can skip kernel_init_pages() if page poisoning is not enabled (because poison would overwrite the zeroes). This avoids redundant zeroing work when freeing pages that are already known to contain all zeros. Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 --- mm/page_alloc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 399e2038dcd9..90a92be96ebf 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1447,7 +1447,14 @@ __always_inline bool __free_pages_prepare(struct page *page, if (kasan_has_integrated_init()) init = false; } - if (init) + /* + * Skip redundant zeroing when the page is already known-zero + * (FPI_ZEROED) and page poisoning did not overwrite it. + * When page_poisoning is enabled, kernel_poison_pages above + * wrote PAGE_POISON (0xAA), so we must re-zero. + */ + if (init && !((fpi_flags & FPI_ZEROED) && + !page_poisoning_enabled_static())) kernel_init_pages(page, 1 << order); /* -- MST