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 4D464C43458 for ; Mon, 29 Jun 2026 16:54:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3D2DB6B0108; Mon, 29 Jun 2026 12:54:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3A9E96B010E; Mon, 29 Jun 2026 12:54:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2E8286B012E; Mon, 29 Jun 2026 12:54:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 0B1C76B0108 for ; Mon, 29 Jun 2026 12:54:21 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 8D98AC08AD for ; Mon, 29 Jun 2026 16:54:20 +0000 (UTC) X-FDA: 84933548280.27.97CD9D4 Received: from one.firstfloor.org (one.firstfloor.org [65.21.254.221]) by imf12.hostedemail.com (Postfix) with ESMTP id BC18D40004 for ; Mon, 29 Jun 2026 16:54:18 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=firstfloor.org header.s=mail header.b=hoWtijM2; spf=pass (imf12.hostedemail.com: domain of andi@firstfloor.org designates 65.21.254.221 as permitted sender) smtp.mailfrom=andi@firstfloor.org; dmarc=none ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1782752059; b=VJlQVknxqH/S4xWdpr8E38VGe9uOZTLhtgEWJOojIVdEG+rU4vy3LnxXjF4whdKNWiR9IJ OW7dAN9QSiWFJ9JBxOL1yx+UPO3dxi3YEkpk0OU6I2dU8K/BLAk93v4KJa++hbE+wuuUB9 F21mzvvDw066PVaCx58PKvgG0dkdNnE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1782752059; 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=V/pQiZoUMv0onkL3b5U2urgbwPUPyC5DN0rKgL9DusY=; b=D87Uot02uSyiyEaVmZpcWMXs2EVrCNZSUlZUNOZnRailacTWqx5frSpDeObceAxxe86A4n kDsCb9QIx1vH4Q7WDd5vE6UcsOGzinnptD8iNxoycKETjf37if3V1+qZCkV+zJMQSDykwG lX49vdW9KBpSzoEAGtryyx0CaUZGX4w= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=firstfloor.org header.s=mail header.b=hoWtijM2; spf=pass (imf12.hostedemail.com: domain of andi@firstfloor.org designates 65.21.254.221 as permitted sender) smtp.mailfrom=andi@firstfloor.org; dmarc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=firstfloor.org; s=mail; t=1782752056; bh=1+OvXKBSJrqCTEswr/10x1x3PFYbvXrrARRRWu8wQWY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hoWtijM2AqSbBKMUTZCq6bVkMzzvKzt5LOopBP1s7dAvMu2N3+HakILYwnzl8+PTo +c3Cmh256PoUfNEjUDL35me5A6xvVF8ay7UTiSdT7LmpKCS0ndfTBXyVjUiG3TtRvK 4ayK3EgxLineaOIqccO9Xquu2luPFw9fRsywBdnQ= Received: by one.firstfloor.org (Postfix, from userid 503) id 3D29B5EAB0; Mon, 29 Jun 2026 18:54:16 +0200 (CEST) Date: Mon, 29 Jun 2026 09:54:16 -0700 From: Andi Kleen To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, David Hildenbrand , Miaohe Lin , Naoya Horiguchi , Andrew Morton , Oscar Salvador , Hidehiro Kawai , Rik van Riel , Vlastimil Babka , Lorenzo Stoakes , "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 , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Hao Li , Kiryl Shutsemau , Byungchul Park , linux-mm@kvack.org, linux-cxl@vger.kernel.org, David Hildenbrand Subject: Re: [PATCH 0/2] mm: memory-failure: fix HWPoison flag race with non-atomic page flag ops Message-ID: References: <20260629033608-mutt-send-email-mst@kernel.org> <20260629043417-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260629043417-mutt-send-email-mst@kernel.org> X-Rspamd-Queue-Id: BC18D40004 X-Stat-Signature: hy1sk3nf6d1fs4d1u44d7mk4hu3jc9sc X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1782752058-924509 X-HE-Meta: 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 aVvPUCWh 4A9UmT0jfBvtH6LOmbuE4wOxmofDPm8z6tNOXVMkO2Fv4TgnDQUI7dR6pVIxiXAhbIX/OJc19vbKWDMi1xnk6wBkrXZmYP48elBGBEMDhtiUjHRpH47zyDJxhl2MpQKMYIM36vtZ7QScluhMoJHiRZyub5GDkdmtqFFU3VX12waama28AWMaaY3P6vH8VhGWaLW+ORFSqNIL3jImafc8Kw7+MmxIJcW4+Ixt+sY3v+N4oBljt5gFUxebVajJiCRgTk8tFIH9VKJ0eoGOf7wgg5u5ibm4HRDkWWUvnoFFUQj+zgq5glnrlAte+SA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > However, this was a basic test, when allocating 4k pages. With 2M hugepages: > > insns/iter cycles/iter > ------------------------------------------------------- > base 20758 +/- 12.5 191208 +/-1946.6 > rcu 20785 +/- 3.7 197108 +/- 132.1 > atomic 20727 +/- 6.4 204591 +/- 160.2 > > rcu vs base +27 (+0.13%) +5900 (+3.09%) > atomic vs base -31 (-0.15%) +13383 (+7.00%) > > and even with THP: > > insns/iter cycles/iter > ------------------------------------------------------- > base 27220 +/- 2.8 192151 +/- 483.3 > rcu 27248 +/- 30.1 194159 +/-2746.6 > atomic 27186 +/- 3.2 200526 +/- 746.2 > > rcu vs base +28 (+0.10%) +2008 (+1.04%) > atomic vs base -34 (-0.12%) +8374 (+4.36%) > > > needs more thought. Well the alternative is to not bother with RCU, but just wait a bit and check if the bit stuck and repeat if needed. While that could in theory livelock it is extremely unlikely (especially if you add a bit of randomization to the sleep) -Andi