From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7D494CD8C9F for ; Mon, 8 Jun 2026 17:51:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8A02D6B0005; Mon, 8 Jun 2026 13:51:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 876C86B0088; Mon, 8 Jun 2026 13:51:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7B3716B008A; Mon, 8 Jun 2026 13:51:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 6A46B6B0005 for ; Mon, 8 Jun 2026 13:51:02 -0400 (EDT) Received: from smtpin29.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 189421638DB for ; Mon, 8 Jun 2026 17:51:02 +0000 (UTC) X-FDA: 84857486364.29.76744E3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf02.hostedemail.com (Postfix) with ESMTP id 7534180018 for ; Mon, 8 Jun 2026 17:51:00 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=FqXdrUY7; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1780941060; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=aHDkkZM0LDnjg910cSwEzql9JdvUeeXv0ZHTIK7GDLE=; b=xEtJf6GmmR4WQxTA28cpb0eTM0s4BKiBZ0rhhKNs5rCQVJgPA+CWYK+TlPLH3+VgA4cKxB gKKbBUYCBgGoJHscqu4c2ZtEmnFIc6z2CWOne7odqPOtczKoFqqtYuMeHPraaDTGpyrDK5 XoTYvPHU7epLoKbQCoD0BkK4+CqRXZs= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=FqXdrUY7; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1780941060; b=SfMWQ5NfEy2SrFP7yxQoym80z4P30HL/aBLfts1RZsybtVzHcOMPVN82n6IeHOOvLFSYNi XELnrZRyBgQhEjjCQ7PVr2HanOripLL/ABSv4NRLV0THWVdoSqS3JDC2gq2LUHPkxrT2d6 KEGLWlm7ZysfsORhbyDznn0rXST5+2Y= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id C6C1E60098; Mon, 8 Jun 2026 17:50:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D24281F00893; Mon, 8 Jun 2026 17:50:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780941059; bh=aHDkkZM0LDnjg910cSwEzql9JdvUeeXv0ZHTIK7GDLE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=FqXdrUY7MnZgXjGyS34UzEp+k9mBFwy1XPyfvBzqH9M5+Rrj97WZggA524whLavtU fex1sh7aoVw9IMLuHbqG0bK53P45PgKGPHUWWGnuSTW9bgc0GPSFWZWjJ5vXQvYnm6 jK3z3oPOO/9d8708nmY88nJxhryP72whFMVt1KqHlIeWHOf9gOvgtu09nP9cF9fTIK NZvYXB/YeKY2j/gbsgK46F08vVHhDMqb/hdaRrs1gnoNECKz8Y7N866XxI2YSKkbTY G82BRdrb2Nid29WdnkhJpE0VI5yr5LASvGW6ohHaH4bsJi3Jr2Wv2m4U+XIdkZsAwh GkNZa8J2v58QQ== Date: Mon, 8 Jun 2026 18:50:46 +0100 From: Lorenzo Stoakes To: Gregory Price Cc: "Vlastimil Babka (SUSE)" , "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, "David Hildenbrand (Arm)" , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , Muchun Song , Oscar Salvador , Andrew Morton , "Liam R. Howlett" , 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 , 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: Re: [PATCH v10 00/37] mm/virtio: skip redundant zeroing of host-zeroed pages Message-ID: References: <8d5d2fa3-a60c-4d04-b3bf-7a8fe89cb1a0@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 7534180018 X-Stat-Signature: oqukwbmue4wuz4yyyatkj893gpopht7c X-Rspam-User: X-HE-Tag: 1780941060-583238 X-HE-Meta: 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 Lnptt3KL mFeio4Z5xi5iMeH5CeRP80orA7bWumfT4rVvb0u4FT6W3vU4VSW0QSg5HbIvP29/k8n9lRdcJW41dvi8Fzuk0j5AceIsjjhszwr/p4vSyrPQDdop0OWVUrkdU+nt9ligW1+jrXgRLQLnD3xUZ0onpC9JgppIZqw2ZiTpGRx4aaWGkL/NQYQWA8pnfxRkkkHeS87Yv+X7CR9c7/VUU6I6Dv8JvT+w0kidJIxUo4YVRLH7EYdDtLMiF3Z9ncRRPCsFy5emUKITzIZyU0n6HRchGZeENkUr6flGW/hMZZRihbOMqrWtM6OOv947SakRh62DeAJMbHVUfGr/k4VA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 08, 2026 at 11:45:18AM -0400, Gregory Price wrote: > On Mon, Jun 08, 2026 at 01:13:42PM +0200, Vlastimil Babka (SUSE) wrote: > > On 6/8/26 13:02, Vlastimil Babka (SUSE) wrote: > > > On 6/8/26 10:33, Michael S. Tsirkin wrote: > > >> Further, on architectures with aliasing caches, upstream with init_on_alloc > > > > > > It seems those are niche architectures so we can ignore that part for perf > > > purposes; the other reason why user_alloc_needs_zeroing() would be true is > > > booting with init_on_alloc. > > > > OK I misread how user_alloc_needs_zeroing() works wrt init_on_alloc, as it's > > negated. But you're changing that anyway to skip that user zeroing, right? > > > > " > > This series eliminates that double-zeroing by moving the zeroing > > into the post_alloc_hook + propagating the "host > > already zeroed this page" information through the buddy allocator. > > " > > > > So relying on "everything in buddy is zeroed" would still work I'd think. > > > > This regresses for anything that previously didn't zero on free or > alloc, which is most kernel allocations. > > I think the scope of this set has increased too much based on early > feedback to fix the userland-initiated allocations piece along with the > balloon/reporting/double-zero piece. That's making all of this > difficult to continue following. Yeah I feel this is 3, 4 or 5 series put together, and there's a lot to discuss in each :) so it's pretty difficult to work with them all put together. These need to be deferred/separated. > > ~Gregory Thanks, Lorenzo