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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 A5904C43460 for ; Tue, 6 Apr 2021 13:41:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E690613D5 for ; Tue, 6 Apr 2021 13:41:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344605AbhDFNlX (ORCPT ); Tue, 6 Apr 2021 09:41:23 -0400 Received: from mx2.suse.de ([195.135.220.15]:46748 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238827AbhDFNlW (ORCPT ); Tue, 6 Apr 2021 09:41:22 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 811DAB1AD; Tue, 6 Apr 2021 13:41:13 +0000 (UTC) Date: Tue, 6 Apr 2021 15:41:07 +0200 From: Oscar Salvador To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Roman Gushchin , Michal Hocko , Shakeel Butt , David Hildenbrand , Muchun Song , David Rientjes , Miaohe Lin , Peter Zijlstra , Matthew Wilcox , HORIGUCHI NAOYA , "Aneesh Kumar K . V" , Waiman Long , Peter Xu , Mina Almasry , Hillf Danton , Joonsoo Kim , Barry Song , Will Deacon , Andrew Morton Subject: Re: [PATCH v4 4/8] hugetlb: create remove_hugetlb_page() to separate functionality Message-ID: References: <20210405230043.182734-1-mike.kravetz@oracle.com> <20210405230043.182734-5-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210405230043.182734-5-mike.kravetz@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 05, 2021 at 04:00:39PM -0700, Mike Kravetz wrote: > +static void remove_hugetlb_page(struct hstate *h, struct page *page, > + bool adjust_surplus) > +{ > + int nid = page_to_nid(page); > + > + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) > + return; > + > + list_del(&page->lru); > + > + if (HPageFreed(page)) { > + h->free_huge_pages--; > + h->free_huge_pages_node[nid]--; > + ClearHPageFreed(page); > + } > + if (adjust_surplus) { > + h->surplus_huge_pages--; > + h->surplus_huge_pages_node[nid]--; > + } > + > + VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page); > + VM_BUG_ON_PAGE(hugetlb_cgroup_from_page_rsvd(page), page); These checks feel a bit odd here. I would move them above, before we start messing with the counters? > + > + ClearHPageTemporary(page); Why clearing it unconditionally? I guess we do not really care, but someone might wonder why when reading the core. So I would either do as we used to do and only clear it in case of HPageTemporary(), or drop a comment. > + set_page_refcounted(page); > + set_compound_page_dtor(page, NULL_COMPOUND_DTOR); > + > + h->nr_huge_pages--; > + h->nr_huge_pages_node[nid]--; > +} As Michal pointed out, remove_hugetlb_page() from alloc_and_dissolve_huge_page() might be problematic in some cases because the new_page has not been enqueued yet. Now, I guess this might be easily fixed with checking list_empty() before going ahead with list_del() call, or with another bool parameter 'delete', with a fat comment explaining why we can get to call remove_huge_page() on a page that is not in any list. Another solution that comes to my mind is to split remove_huge_page() functionality in 1) delete from list + unaccount free and surplus pages and 2) reset page's state + unaccount nr_huge_pages But that might be just biased as would fit for my usecase. So maybe a list_empty() or the bool parameter might just do. -- Oscar Salvador SUSE L3