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 2E3F8C433E0 for ; Tue, 12 Jan 2021 14:24:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0405023123 for ; Tue, 12 Jan 2021 14:24:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729809AbhALOY1 (ORCPT ); Tue, 12 Jan 2021 09:24:27 -0500 Received: from mx2.suse.de ([195.135.220.15]:57818 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725901AbhALOY0 (ORCPT ); Tue, 12 Jan 2021 09:24:26 -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=1610461420; 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=Xq1aHA8mbrEMaD5Ve0Fl96EfFqk/5ogr68Z+fQaO8D0=; b=rUyrJvvcNbludVlUMXKtBj3FaVcKKFoarrUICH/TobbkfNZkK39iW75Q5mw6kJSYFlMv4C +y7k9AL7Bkw4C24ytYRjCo3wyfRfly53q4h6kkVvkpGMxSlAXrcVjXCX03QFH04c/Idxyc GaJB/Xwnvn1U5zgx6D/kdpigldIaG28= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 55864ABD6; Tue, 12 Jan 2021 14:23:40 +0000 (UTC) Date: Tue, 12 Jan 2021 15:23:37 +0100 From: Michal Hocko To: David Hildenbrand Cc: Muchun Song , mike.kravetz@oracle.com, akpm@linux-foundation.org, n-horiguchi@ah.jp.nec.com, ak@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yang Shi Subject: Re: [PATCH v3 1/6] mm: migrate: do not migrate HugeTLB page whose refcount is one Message-ID: <20210112142337.GR22493@dhcp22.suse.cz> References: <20210110124017.86750-1-songmuchun@bytedance.com> <20210110124017.86750-2-songmuchun@bytedance.com> <1b39d654-0b8c-de3a-55d1-6ab8c2b2e0ba@redhat.com> <20210112112709.GO22493@dhcp22.suse.cz> <20210112121643.GP22493@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210112121643.GP22493@dhcp22.suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 12-01-21 13:16:45, Michal Hocko wrote: [...] > Well, currently pool pages are not migrateable but you are right that > this is likely something that we will need to look into in the future > and this optimization would stand in the way. After some more thinking I believe I was wrong in my last statement. This optimization shouldn't have any effect on pages on the pool as those stay at reference count 0 and they cannot be isolated either (clear_page_huge_active before it is enqueued). That being said, the migration code would still have to learn about about this pages but that is out of scope of this discussion. Sorry about the confusion from my side. -- Michal Hocko SUSE Labs