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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A9BBECAAD8 for ; Thu, 15 Sep 2022 02:49:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 780FB8D0001; Wed, 14 Sep 2022 22:49:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 731A16B0073; Wed, 14 Sep 2022 22:49:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5F8CE8D0001; Wed, 14 Sep 2022 22:49:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 50DC86B0071 for ; Wed, 14 Sep 2022 22:49:30 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 237DDAAFA1 for ; Thu, 15 Sep 2022 02:49:30 +0000 (UTC) X-FDA: 79912788900.27.2CA1F38 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf05.hostedemail.com (Postfix) with ESMTP id 7AB4A1000B7 for ; Thu, 15 Sep 2022 02:49:29 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0A66D1063; Wed, 14 Sep 2022 19:49:35 -0700 (PDT) Received: from [10.162.43.6] (unknown [10.162.43.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C76C63F71A; Wed, 14 Sep 2022 19:49:25 -0700 (PDT) Message-ID: Date: Thu, 15 Sep 2022 08:19:22 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] mm/hugetlb: correct demote page offset logic Content-Language: en-US To: Mike Kravetz , Doug Berger , Andrew Morton Cc: Muchun Song , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20220914190917.3517663-1-opendmb@gmail.com> From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf05.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663210169; a=rsa-sha256; cv=none; b=KvkMxQx6gFuwNJ9SC+uiFEfcwmHBfQV+HBPjmG/hKQ1o3o8QPGwr5r82XKu7pPIe75XrRs zK1ewzSfxUJMyoVMHR1fJ4LKIscgy2zL0o5p5A+nfxR7kYiVv8yY+M/p2uZNQPSe6Vjknl GKak81HFCoqAum/pDUFt/UlRaDKWC+w= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663210169; 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; bh=xUwyX1msHoJS+tshFPJ2fPgjV7myfYRITsUI4Mywh5E=; b=HGTEy8J3N0KCLv4cXj9M3HF4f+6OHHF1tbrYD4mcU4Ddco+nzUuUY2ycSMZh1CfUhHqCVt jup7Nk3+kT7DegG10OLD1KpaCUbWcIujZg2OcwqRAicQvavhmm7w9fpensOFimfIPbfKLS iEKv2RAzlCClI3d41ypGbIM0exiETvU= Authentication-Results: imf05.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf05.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com X-Rspam-User: X-Rspamd-Queue-Id: 7AB4A1000B7 X-Rspamd-Server: rspam01 X-Stat-Signature: cg9eqzye5qj9ah963tnosmrtm6cw51e1 X-HE-Tag: 1663210169-315540 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 9/15/22 02:48, Mike Kravetz wrote: > On 09/14/22 12:09, Doug Berger wrote: >> With gigantic pages it may not be true that struct page structures >> are contiguous across the entire gigantic page. The nth_page macro >> is used here in place of direct pointer arithmetic to correct for >> this. >> >> Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support") >> Signed-off-by: Doug Berger >> Cc: >> --- >> mm/hugetlb.c | 14 ++++++++------ >> 1 file changed, 8 insertions(+), 6 deletions(-) > > Thanks! > > Reviewed-by: Mike Kravetz > > To answer Andrew's question about user-visible runtime effects. > We could get addressing exceptions. However, this is only possible in > configurations where CONFIG_SPARSEMEM && !CONFIG_SPARSEMEM_VMEMMAP. > Such a configuration option is rare an unknown to be the default > anywhere. In that case, should this be a 'Cc: stable' ? Although it does fix the above mentioned commit for a possible configuration. But should this be backported, if there could not have been an affected system ?