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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 D3FADC433E6 for ; Wed, 17 Feb 2021 13:55:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E97F64D9A for ; Wed, 17 Feb 2021 13:55:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233060AbhBQNzU (ORCPT ); Wed, 17 Feb 2021 08:55:20 -0500 Received: from mx2.suse.de ([195.135.220.15]:51728 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232927AbhBQNzR (ORCPT ); Wed, 17 Feb 2021 08:55:17 -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=1613570070; 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=cGZn21Gwdacac4lJmjWs7og7us1pnxGAs5d/KiaX3Wc=; b=CuQ9syD5a9/plxWcOzZtRtU/gUDxV/DyJ0MWCNEZtRqMzA8snhlchgrKXuAE2Q1zyxViaV 9xFeI788BLis5xvMfejXS8fJoIkVbzlPDoFiCL6Uw6el5F4xYJQRz2cP9+CC345O21bZkR SnLE+caGcsCCV5znjNj/2XAkg36h4PY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D2997B761; Wed, 17 Feb 2021 13:54:30 +0000 (UTC) Date: Wed, 17 Feb 2021 14:54:24 +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 2/2] mm: Make alloc_contig_range handle in-use hugetlb pages Message-ID: References: <20210217100816.28860-1-osalvador@suse.de> <20210217100816.28860-3-osalvador@suse.de> <20210217134649.GB32488@linux> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210217134649.GB32488@linux> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 17-02-21 14:46:49, Oscar Salvador wrote: > On Wed, Feb 17, 2021 at 02:36:31PM +0100, Michal Hocko wrote: > > On Wed 17-02-21 11:08:16, Oscar Salvador wrote: > > > In-use hugetlb pages can be migrated as any other page (LRU > > > and Movable), so let alloc_contig_range handle them. > > > > > > All we need is to succesfully isolate such page. > > > > Again, this is missing a problem statement and a justification why we > > want/need this. > > Heh, I was poor in words. > > "alloc_contig_range() will fail miserably if it finds a HugeTLB page within > the range without a chance to handle them. Since HugeTLB pages can be migrated > as any other page (LRU and Movable), it does not make sense to bail out. > Enable the interface to recognize in-use HugeTLB pages and have a chance > to migrate them" > > What about something along those lines? Is this a real life problem? I know we _can_ but I do not see any reasoning _why_ should we care all that much. -- Michal Hocko SUSE Labs