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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 17111C433DB for ; Fri, 26 Feb 2021 08:48:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B001160231 for ; Fri, 26 Feb 2021 08:48:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230306AbhBZIry (ORCPT ); Fri, 26 Feb 2021 03:47:54 -0500 Received: from mx2.suse.de ([195.135.220.15]:50378 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230199AbhBZIro (ORCPT ); Fri, 26 Feb 2021 03:47:44 -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=1614329218; 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=j6G83ahZDtYiFerun3sUeslIIVf/Z0b4Gpz4M3WMigY=; b=fSkzNTJtCQTQ/qzBGXzntlfnpi6JPRoSY8ESSQfRMKUq/K+0gW/MW+37fIbDrriunt/2vq 0CiQy0aKPz6vd+SwWb4tsLFMxd1u8ajmPMD10dgwWT/U/Fr/bTnW8sLA5rSOyHl1JOdQus W8O2MjYv5/ZsoRCVmVvIQCI+mKod9HQ= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4D742AC6E; Fri, 26 Feb 2021 08:46:58 +0000 (UTC) Date: Fri, 26 Feb 2021 09:46:57 +0100 From: Michal Hocko To: Oscar Salvador Cc: Andrew Morton , Mike Kravetz , David Hildenbrand , Muchun Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 2/2] mm: Make alloc_contig_range handle in-use hugetlb pages Message-ID: References: <20210222135137.25717-1-osalvador@suse.de> <20210222135137.25717-3-osalvador@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210222135137.25717-3-osalvador@suse.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 22-02-21 14:51:37, Oscar Salvador wrote: [...] > @@ -2394,9 +2397,19 @@ bool isolate_or_dissolve_huge_page(struct page *page) > */ > if (hstate_is_gigantic(h)) > return ret; > - > - if (!page_count(head) && alloc_and_dissolve_huge_page(h, head)) > +retry: > + if (page_count(head) && isolate_huge_page(head, list)) { > ret = true; > + } else if (!page_count(head)) { This is rather head spinning. Do we need to test page_count in the else branch? Do you want to optimize for a case where the page cannot be isolated because of page_huge_active? > + int err = alloc_and_dissolve_huge_page(h, head); > + > + if (!err) { > + ret = true; > + } else if (err == -EBUSY && try_again) { > + try_again = false; > + goto retry; > + } Is this retry once logic really needed? Does it really give us any real benefit? alloc_and_dissolve_huge_page already retries when the page is being freed. -- Michal Hocko SUSE Labs