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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 BBA77C5519F for ; Fri, 20 Nov 2020 08:26:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 493EC22244 for ; Fri, 20 Nov 2020 08:26:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="DcriLmSI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727070AbgKTIZy (ORCPT ); Fri, 20 Nov 2020 03:25:54 -0500 Received: from mx2.suse.de ([195.135.220.15]:41726 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726335AbgKTIZy (ORCPT ); Fri, 20 Nov 2020 03:25:54 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1605860753; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/oTRUaXAkYZygv3UYXt9E76OSLD00b7IWkOMbS8VPYQ=; b=DcriLmSI4f5H4oP0GWaRgjSuOqA7oZrxcDDFHKyxbNxbzD8/TTcfgNdpMsQwzOIR2+ugd0 Wgq/7T/NznJ7gUMNJqV4wT8JjqtoCqB92NnGby/owput568qoAf0diC/e+DphHSS+PSKW1 BPFcOgn8cCRkQRK+WDmlhz5EOGwqDHw= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C37C3AFDC; Fri, 20 Nov 2020 08:25:52 +0000 (UTC) Date: Fri, 20 Nov 2020 09:25:52 +0100 From: Michal Hocko To: Muchun Song Cc: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, osalvador@suse.de, song.bao.hua@hisilicon.com, duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v5 21/21] mm/hugetlb: Disable freeing vmemmap if struct page size is not power of two Message-ID: <20201120082552.GI3200@dhcp22.suse.cz> References: <20201120064325.34492-1-songmuchun@bytedance.com> <20201120064325.34492-22-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201120064325.34492-22-songmuchun@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 20-11-20 14:43:25, Muchun Song wrote: > We only can free the unused vmemmap to the buddy system when the > size of struct page is a power of two. Can we actually have !power_of_2 struct pages? > > Signed-off-by: Muchun Song > --- > mm/hugetlb_vmemmap.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index c3b3fc041903..7bb749a3eea2 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -671,7 +671,8 @@ void __init hugetlb_vmemmap_init(struct hstate *h) > unsigned int order = huge_page_order(h); > unsigned int vmemmap_pages; > > - if (hugetlb_free_vmemmap_disabled) { > + if (hugetlb_free_vmemmap_disabled || > + !is_power_of_2(sizeof(struct page))) { > pr_info("disable free vmemmap pages for %s\n", h->name); > return; > } > -- > 2.11.0 > -- Michal Hocko SUSE Labs