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 BD5B8C433DB for ; Mon, 8 Mar 2021 15:43:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79F536521D for ; Mon, 8 Mar 2021 15:43:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229690AbhCHPnQ (ORCPT ); Mon, 8 Mar 2021 10:43:16 -0500 Received: from mx2.suse.de ([195.135.220.15]:39306 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229459AbhCHPmq (ORCPT ); Mon, 8 Mar 2021 10:42:46 -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=1615218165; 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=PSwAr01wd8o8Gcv7XoZ8VHOldRlri/BnhPEeNOyHtBc=; b=kOCeT9ZjJ57p59c0D18mLh85tj1k/zY1lAzk/tqohe4PTVOW9pCHNrOAzxSZ66Fx+c1rbU 9n12STBBoSSmTvK7t7UK7pN7SsPXjPeX+eiF9R36bUFqIlacqTkxBp9nrAR3+G39hXaf5M Y4UkVEToPD7Vn2xo+NU1rOrYKrLzmUM= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A20A8AE05; Mon, 8 Mar 2021 15:42:45 +0000 (UTC) Date: Mon, 8 Mar 2021 16:42:43 +0100 From: Michal Hocko To: David Hildenbrand Cc: Minchan Kim , Andrew Morton , linux-mm , LKML , joaodias@google.com Subject: Re: [PATCH] mm: be more verbose for alloc_contig_range faliures Message-ID: References: <9f7b4b8a-5317-e382-7f21-01667e017982@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9f7b4b8a-5317-e382-7f21-01667e017982@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 08-03-21 15:13:35, David Hildenbrand wrote: > On 08.03.21 15:11, Michal Hocko wrote: > > On Mon 08-03-21 14:22:12, David Hildenbrand wrote: > > > On 08.03.21 13:49, Michal Hocko wrote: > > [...] > > > > Earlier in the discussion I have suggested dynamic debugging facility. > > > > Documentation/admin-guide/dynamic-debug-howto.rst. Have you tried to > > > > look into that direction? > > > > > > Did you see the previous mail this is based on: > > > > > > https://lkml.kernel.org/r/YEEUq8ZRn4WyYWVx@google.com > > > > > > I agree that "nofail" is misleading. Rather something like > > > "dump_on_failure", just a better name :) > > > > Yeah, I have read through the email thread. I just do not get why we > > cannot make it pr_debug() and add -DDYNAMIC_DEBUG_MODULE for > > page_alloc.c (I haven't checked whether that is possible for built in > > compile units, maybe it is not but from a quick seems it should). > > > > I really do not like this to be a part of the API. alloc_contig_range is > > Which API? Any level of the alloc_contig_range api because I strongly suspect that once there is something on the lower levels there will be a push to have it in the directly consumed api as well. Besides that I think this is just a wrong way to approach the problem. > It does not affect alloc_contig_range() itself, it's used > internally only. Sure, we could simply pr_debug() for each and every > migration failure. As long as it's default-disabled, sure. > > I do agree that we should look into properly including this into the dynamic > debugging ifrastructure. Yeah, unless we learn this is not feasible for some reason, which I do not see right now, then let's just make it pr_debug with the runtime control. -- Michal Hocko SUSE Labs