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_CR_TRAILER, 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 4EC0BC433DB for ; Wed, 10 Feb 2021 12:27:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B41C64E31 for ; Wed, 10 Feb 2021 12:27:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230267AbhBJM1K (ORCPT ); Wed, 10 Feb 2021 07:27:10 -0500 Received: from mx2.suse.de ([195.135.220.15]:58964 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230259AbhBJMX7 (ORCPT ); Wed, 10 Feb 2021 07:23:59 -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=1612959791; 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=dsqc8ndJdURpL2hssLBy0cKI35i8iQHpKXZ5s9miM54=; b=Gwrjv6r+Ug52YikQrv8w1KdjcXPsc4u2zdbH8P4PWBeGlz0o8NjmprdDO3TjIcmfIMBsRB 9e95oVVNUsDnWNRer+IMs419+lpFOKDszcrS1khEvQv24F5cHhF174xQRJrE5Wn2NifYCj XnUZKazgkdiOIve3hGp3LkOuR6ppgYM= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id BEF6AAC97; Wed, 10 Feb 2021 12:23:11 +0000 (UTC) Date: Wed, 10 Feb 2021 13:23:10 +0100 From: Michal Hocko To: Minchan Kim Cc: Oscar Salvador , David Hildenbrand , Vlastimil Babka , Andrew Morton , linux-mm , LKML Subject: Re: [PATCH] mm: remove lru_add_drain_all in alloc_contig_range Message-ID: References: <20210209175048.361638-1-minchan@kernel.org> <20210209190332.GA3363@localhost.localdomain> <49491777-6d61-db4d-5e90-7a8b9045faca@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49491777-6d61-db4d-5e90-7a8b9045faca@suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 10-02-21 13:17:33, Vlastimil Babka wrote: > On 2/9/21 8:03 PM, Oscar Salvador wrote: > > On Tue, Feb 09, 2021 at 07:17:59PM +0100, David Hildenbrand wrote: > >> I was expecting some magical reason why this is still required but I am not > >> able to find a compelling one. Maybe this is really some historical > >> artifact. > >> > >> Let's see if other people know why this call here still exists. > > > > I also stumbled upon this while working on adding hugetlb support for > > alloc_acontig_range [1]. > > I have to confess I puzzled me a bit. > > > > I saw it going back to when the function was first introduced by > > > > commit 041d3a8cdc18dc375a128d90bbb753949a81b1fb > > Author: Michal Nazarewicz > > Date: Thu Dec 29 13:09:50 2011 +0100 > > > > mm: page_alloc: introduce alloc_contig_range() > > > > > > It does not make much sense to me. At this point our pages are free, so > > we do not care about LRU handling here. > > But I might be missing something. > > AFAICS, at the time page migration used putback_lru_page() to release the > migration source page. This would put the page on lru pvec even if it was in > fact not mapped anywhere anymore, and only the drain would actually free it. > Seems Minchan optimized this in 2016 by c6c919eb90e0 ("mm: use put_page() to > free page instead of putback_lru_page()") This would be a great addition to the changelog. Thanks a lot Vlastimil, you saved me from some archeology. With that mentioned feel free to add Acked-by: Michal Hocko > > > [1] https://lore.kernel.org/linux-mm/20210208103935.GA32103@linux/T/#md651fc6e73c656105179382f92f8b2d6073051d1 > > > > > -- Michal Hocko SUSE Labs