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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 3C016C67863 for ; Mon, 22 Oct 2018 13:47:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 355212064C for ; Mon, 22 Oct 2018 13:46:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 355212064C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728175AbeJVWFi (ORCPT ); Mon, 22 Oct 2018 18:05:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:49938 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727820AbeJVWFi (ORCPT ); Mon, 22 Oct 2018 18:05:38 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0272FAE8B; Mon, 22 Oct 2018 13:46:57 +0000 (UTC) Date: Mon, 22 Oct 2018 15:46:57 +0200 From: Michal Hocko To: Vlastimil Babka Cc: "Kirill A. Shutemov" , Andrew Morton , Mel Gorman , David Rientjes , Andrea Argangeli , Zi Yan , Stefan Priebe - Profihost AG , linux-mm@kvack.org, LKML Subject: Re: [PATCH 2/2] mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask Message-ID: <20181022134657.GG18839@dhcp22.suse.cz> References: <20180925120326.24392-1-mhocko@kernel.org> <20180925120326.24392-3-mhocko@kernel.org> <20180926133039.y7o5x4nafovxzh2s@kshutemo-mobl1> <20180926141708.GX6278@dhcp22.suse.cz> <20180926142227.GZ6278@dhcp22.suse.cz> <26cb01ff-a094-79f4-7ceb-291e5e053c58@suse.cz> <20181022133058.GE18839@dhcp22.suse.cz> <18476b0b-7300-f340-5845-9de0a019c65c@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <18476b0b-7300-f340-5845-9de0a019c65c@suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 22-10-18 15:35:24, Vlastimil Babka wrote: > On 10/22/18 3:30 PM, Michal Hocko wrote: > > On Mon 22-10-18 15:15:38, Vlastimil Babka wrote: > >>> Forgot to add. One notable exception would be that the previous code > >>> would allow to hit > >>> WARN_ON_ONCE(policy->mode == MPOL_BIND && (gfp & __GFP_THISNODE)); > >>> in policy_node if the requested node (e.g. cpu local one) was outside of > >>> the mbind nodemask. This is not possible now. We haven't heard about any > >>> such warning yet so it is unlikely that it happens though. > >> > >> I don't think the previous code could hit the warning, as the hugepage > >> path that would add __GFP_THISNODE didn't call policy_node() (containing > >> the warning) at all. IIRC early of your patch did hit the warning > >> though, which is why you added the MPOL_BIND policy check. > > > > Are you sure? What prevents node_isset(node, policy_nodemask()) == F and > > fallback to the !huge allocation path? > > That can indeed happen, but then the code also skipped the "gfp |= > __GFP_THISNODE" part, right? So the warning wouldn't trigger. I thought I have crawled all the code paths back then but maybe there were some phantom ones... If you are sure about then we can stick with the original changelog. -- Michal Hocko SUSE Labs