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 3F96EC43458 for ; Mon, 29 Jun 2026 17:04:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 178496B011F; Mon, 29 Jun 2026 13:04:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 129BA6B0121; Mon, 29 Jun 2026 13:04:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EE6196B0124; Mon, 29 Jun 2026 13:04:38 -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 C42156B011F for ; Mon, 29 Jun 2026 13:04:38 -0400 (EDT) Received: from smtpin17.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 16DB3C12CF for ; Mon, 29 Jun 2026 17:04:37 +0000 (UTC) X-FDA: 84933574194.17.ACD5372 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf18.hostedemail.com (Postfix) with ESMTP id 2CEB21C0011 for ; Mon, 29 Jun 2026 17:04:35 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="KR+HDkX/"; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1782752675; b=e5HefH/nNojHkJbePHuk/bZsUEwsDzDGy+KbsJArkmI/wwpyNGTa94tfyGJJrs8OLdh/io 71aGjNPPIoHEhm4j9p87hd8CsOjvWHGxKkk1f5MO+Gj053W8nGdFtPWLJDncd/fX3YiC9T /E4xZi4bidUEr7uJZDJNXh1H9LnlAts= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1782752675; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Ul6f7sQKvd0dorXycCkumAOsgczpxyVqCRrPVWEZxzE=; b=bg2Om6zoVE3FGxvJuT9ClRrIbo3HUaCOSFR0F8F4C4yVfqundfC1Gl6AV21SGZGYuGebQS SWObs9NivG4RuZpAu4E0epsG8KhH8yJU0n0m39TlDypCvsDV0oSU7eabn9zm+MZPV6ZY3C CZb1j4k6JcGkPE3pmHdqByWB7op1T/8= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="KR+HDkX/"; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 60E2342A7F; Mon, 29 Jun 2026 17:04:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E80491F000E9; Mon, 29 Jun 2026 17:04:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782752674; bh=Ul6f7sQKvd0dorXycCkumAOsgczpxyVqCRrPVWEZxzE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=KR+HDkX/e+DWcI70K4NbnOWmimZctb8DsZesFzOfoRbt2YiJJd5ywFThe+vJUJZdh p63fxw//X5QEMiVKFfh+/Xo7AbACmQSqVfULumqMNXeqwt7oYJdiswxglOvpvm+gYP RuBv/kqyqTbU50PT22VB7eCTe1A12DHVqVdOoo56Y4B6UyZeBUUWz9OKlMZ8FyaPhJ +LLqVW339hEBK/8pv6fsO0HBTB4ZgQT69C7X+n022la3K8wqD1ZFVfO0XvoFWTY1AS pq3oPNKGNHJOSTzC5LxbaMmsFi/5xTr02h+zqPvJgtGu4vb69ixMJRmkmRaMkE8uxw NltG1ROyCmuVw== Message-ID: <20a5dfd4-b3c7-450a-8a70-08d0345aade4@kernel.org> Date: Mon, 29 Jun 2026 19:04:25 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] mm: memory-failure: fix HWPoison flag race with non-atomic page flag ops To: Andi Kleen , "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Miaohe Lin , Naoya Horiguchi , Andrew Morton , Oscar Salvador , Hidehiro Kawai , Rik van Riel , Vlastimil Babka , Lorenzo Stoakes , "Liam R. 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 2CEB21C0011 X-Stat-Signature: g55xxcfmodxkntkb4pe16qa8d9r43gtc X-HE-Tag: 1782752675-267238 X-HE-Meta: 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 aSf6TRZD 0ZTkQGohIeBO5uhlfx/z16v0JrJnb4tBOUiKmRq3tZbQof3JdKW3ILx0sUMDOr75gCxK6oHeBoiwGsVL50TsEDRBGp6OUqyl7mntkfuQJdKMJdZ6527ccUPiHnpfXFH+bRQqL3Dsdj/ao75kqApkmbB5M4gYoFfWEz/vklxtWnjkXB5vbX3HqOCDL5Om2gpFhinWzZoGyl4LwK+l4DENA7p4FizCXgVnzHDaUCdyIjgmUcO2ejO5gDsaetz5vN9kMhSWGpyeHpeKAxf13sXaDjoNeEmz3mzEtyT8LXKfgKfErrUU2LYoGqvLFuxX+rewFoybgWgMFYKgdz03G6jfZJXp78g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/29/26 18:54, Andi Kleen wrote: >> 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) We discussed that a bit already. Hypervisors make it fairly unpredictable how long you would actually have to spin. -- Cheers, David