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 3FA9EECAAD3 for ; Thu, 15 Sep 2022 04:04:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 729626B0071; Thu, 15 Sep 2022 00:04:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6B16F8D0002; Thu, 15 Sep 2022 00:04:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 551878D0001; Thu, 15 Sep 2022 00:04:23 -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 429F26B0071 for ; Thu, 15 Sep 2022 00:04:23 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 148021207B1 for ; Thu, 15 Sep 2022 04:04:23 +0000 (UTC) X-FDA: 79912977606.27.9642730 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf16.hostedemail.com (Postfix) with ESMTP id 862E01800A2 for ; Thu, 15 Sep 2022 04:04:21 +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 17FC11682; Wed, 14 Sep 2022 21:04:27 -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 105FB3F71A; Wed, 14 Sep 2022 21:04:17 -0700 (PDT) Message-ID: Date: Thu, 15 Sep 2022 09:34:15 +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: Doug Berger , Mike Kravetz , Muchun Song Cc: Andrew Morton , 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: <20220914190917.3517663-1-opendmb@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663214661; a=rsa-sha256; cv=none; b=qwqCbad66kCZO0rVnW+hP2L5Xn8M0Xcbwtkk1VaVQh3Fvc9UmVfrzmptI3PBpM3pcGaywL OQvZBYri5YPo8v7IUSmUnKbY5dsqXuJTOJMJeUtLKkwU6d0nHqkA3KFxbv5N9kF825DQZV K6I89OWRkDnsGGB4fPFDl46YEe3lIIQ= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=none; spf=pass (imf16.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663214661; 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=dGenGNFixSUfvjBcMpAQ6R5uUlnwP9tMHtyYapDVSlA=; b=RrwBDc0Hs/m0uc3mqD1UQ1umG7xyT8wEx/lrZxnynZi/zoGriN73WKYom1If5hfYDWK+ON Ek5GtYLUT1OKw0w43S1uShQiHmXpepuMIaf7kb0xBcthkqgPMKm0QxCA6epDvf19ylfmRG XjR0gVDkg+Y7c/fGTqF1jhMfG58Z4Mo= Authentication-Results: imf16.hostedemail.com; dkim=none; spf=pass (imf16.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com; dmarc=pass (policy=none) header.from=arm.com X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: er67bwbzzkbw9htx9ikfob787adatfys X-Rspamd-Queue-Id: 862E01800A2 X-HE-Tag: 1663214661-40560 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 00:39, 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: Reviewed-by: Anshuman Khandual > --- > mm/hugetlb.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index e070b8593b37..0bdfc7e1c933 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -3420,6 +3420,7 @@ static int demote_free_huge_page(struct hstate *h, struct page *page) > { > int i, nid = page_to_nid(page); > struct hstate *target_hstate; > + struct page *subpage; > int rc = 0; > > target_hstate = size_to_hstate(PAGE_SIZE << h->demote_order); > @@ -3453,15 +3454,16 @@ static int demote_free_huge_page(struct hstate *h, struct page *page) > mutex_lock(&target_hstate->resize_lock); > for (i = 0; i < pages_per_huge_page(h); > i += pages_per_huge_page(target_hstate)) { > + subpage = nth_page(page, i); > if (hstate_is_gigantic(target_hstate)) > - prep_compound_gigantic_page_for_demote(page + i, > + prep_compound_gigantic_page_for_demote(subpage, > target_hstate->order); > else > - prep_compound_page(page + i, target_hstate->order); > - set_page_private(page + i, 0); > - set_page_refcounted(page + i); > - prep_new_huge_page(target_hstate, page + i, nid); > - put_page(page + i); > + prep_compound_page(subpage, target_hstate->order); > + set_page_private(subpage, 0); > + set_page_refcounted(subpage); > + prep_new_huge_page(target_hstate, subpage, nid); > + put_page(subpage); > } > mutex_unlock(&target_hstate->resize_lock); >