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 X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D145C433DF for ; Mon, 6 Jul 2020 22:14:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D553A206E9 for ; Mon, 6 Jul 2020 22:14:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726864AbgGFWOT convert rfc822-to-8bit (ORCPT ); Mon, 6 Jul 2020 18:14:19 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:2535 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725942AbgGFWOT (ORCPT ); Mon, 6 Jul 2020 18:14:19 -0400 Received: from dggemi404-hub.china.huawei.com (unknown [172.30.72.57]) by Forcepoint Email with ESMTP id 2A032ACAB1B20B52FFF3; Tue, 7 Jul 2020 06:14:17 +0800 (CST) Received: from DGGEMI525-MBS.china.huawei.com ([169.254.6.177]) by dggemi404-hub.china.huawei.com ([10.3.17.142]) with mapi id 14.03.0487.000; Tue, 7 Jul 2020 06:14:10 +0800 From: "Song Bao Hua (Barry Song)" To: Roman Gushchin CC: "akpm@linux-foundation.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Linuxarm , Mike Kravetz , Jonathan Cameron Subject: RE: [PATCH] mm/hugetlb: avoid hardcoding while checking if cma is reserved Thread-Topic: [PATCH] mm/hugetlb: avoid hardcoding while checking if cma is reserved Thread-Index: AQHWU3HjjsPjy1jnSk6RkQtfiUWhe6j6kUUAgACKkEA= Date: Mon, 6 Jul 2020 22:14:10 +0000 Message-ID: References: <20200706084405.14236-1-song.bao.hua@hisilicon.com> <20200706214808.GB152560@carbon.lan> In-Reply-To: <20200706214808.GB152560@carbon.lan> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.126.201.98] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Roman Gushchin [mailto:guro@fb.com] > Sent: Tuesday, July 7, 2020 9:48 AM > To: Song Bao Hua (Barry Song) > Cc: akpm@linux-foundation.org; linux-mm@kvack.org; > linux-kernel@vger.kernel.org; Linuxarm ; Mike > Kravetz ; Jonathan Cameron > > Subject: Re: [PATCH] mm/hugetlb: avoid hardcoding while checking if cma is > reserved > > On Mon, Jul 06, 2020 at 08:44:05PM +1200, Barry Song wrote: > > Hello, Barry! > > > hugetlb_cma[0] can be NULL due to various reasons, for example, node0 has > > no memory. Thus, NULL hugetlb_cma[0] doesn't necessarily mean cma is not > > enabled. gigantic pages might have been reserved on other nodes. > > Just curious, is it a real-life problem you've seen? If so, I wonder how > you're using the hugetlb_cma option, and what's the outcome? Yes. It is kind of stupid but I once got a board on which node0 has no DDR though node1 and node3 have memory. I actually prefer we get cma size of per node by: cma size of one node = hugetlb_cma/ (nodes with memory) rather than: cma size of one node = hugetlb_cma/ (all online nodes) but unfortunately, or the N_MEMORY infrastructures are not ready yet. I mean: for_each_node_state(nid, N_MEMORY) { int res; size = min(per_node, hugetlb_cma_size - reserved); size = round_up(size, PAGE_SIZE << order); res = cma_declare_contiguous_nid(0, size, 0, PAGE_SIZE << order, 0, false, "hugetlb", &hugetlb_cma[nid], nid); ... } > > > > > Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages > using cma") > > Cc: Roman Gushchin > > Cc: Mike Kravetz > > Cc: Jonathan Cameron > > Signed-off-by: Barry Song > > --- > > mm/hugetlb.c | 18 +++++++++++++++--- > > 1 file changed, 15 insertions(+), 3 deletions(-) > > > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > > index 57ece74e3aae..603aa854aa89 100644 > > --- a/mm/hugetlb.c > > +++ b/mm/hugetlb.c > > @@ -2571,9 +2571,21 @@ static void __init > hugetlb_hstate_alloc_pages(struct hstate *h) > > > > for (i = 0; i < h->max_huge_pages; ++i) { > > if (hstate_is_gigantic(h)) { > > - if (IS_ENABLED(CONFIG_CMA) && hugetlb_cma[0]) { > > - pr_warn_once("HugeTLB: hugetlb_cma is enabled, skip > boot time allocation\n"); > > - break; > > + if (IS_ENABLED(CONFIG_CMA)) { > > + int nid; > > + bool cma_reserved = false; > > + > > + for_each_node_state(nid, N_ONLINE) { > > + if (hugetlb_cma[nid]) { > > + pr_warn_once("HugeTLB: hugetlb_cma is > reserved," > > + "skip boot time allocation\n"); > > + cma_reserved = true; > > + break; > > + } > > + } > > + > > + if (cma_reserved) > > + break; > > It's a valid problem, and I like to see it fixed. But I wonder if it would be better > to introduce a new helper bool hugetlb_cma_enabled()? And move both > IS_ENABLED(CONFIG_CMA) > and hugetlb_cma[nid] checks there? Yep. that would be more readable. > > Thank you! Thanks Barry