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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 11424C4332B for ; Tue, 2 Mar 2021 07:11:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5040600CD for ; Tue, 2 Mar 2021 07:11:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1575181AbhCBDx5 (ORCPT ); Mon, 1 Mar 2021 22:53:57 -0500 Received: from mx2.suse.de ([195.135.220.15]:34534 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241351AbhCAWF5 (ORCPT ); Mon, 1 Mar 2021 17:05:57 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id CA236AB8C; Mon, 1 Mar 2021 22:05:14 +0000 (UTC) Date: Mon, 1 Mar 2021 23:05:12 +0100 From: Oscar Salvador To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Minchan Kim , Michal Hocko , Vlastimil Babka Subject: Re: [PATCH v1] mm/page_alloc: drop pr_info_ratelimited() in alloc_contig_range() Message-ID: <20210301220512.GA4425@localhost.localdomain> References: <20210301150945.77012-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210301150945.77012-1-david@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 01, 2021 at 04:09:45PM +0100, David Hildenbrand wrote: > The information that some PFNs are busy is: > a) not helpful for ordinary users: we don't even know *who* called > alloc_contig_range(). This is certainly not worth a pr_info.*(). > b) not really helpful for debugging: we don't have any details *why* > these PFNs are busy, and that is what we usually care about. > c) not complete: there are other cases where we fail alloc_contig_range() > using different paths that are not getting recorded. > > For example, we reach this path once we succeeded in isolating pageblocks, > but failed to migrate some pages - which can happen easily on > ZONE_NORMAL (i.e., has_unmovable_pages() is racy) but also on ZONE_MOVABLE > i.e., we would have to retry longer to migrate). > > For example via virtio-mem when unplugging memory, we can create quite > some noise (especially with ZONE_NORMAL) that is not of interest to > users - it's expected that some allocations may fail as memory is busy. > > Let's just drop that pr_info_ratelimit() and rather implement a dynamic > debugging mechanism in the future that can give us a better reason why > alloc_contig_range() failed on specific pages. > > Cc: Andrew Morton > Cc: Minchan Kim > Cc: Oscar Salvador > Cc: Michal Hocko > Cc: Vlastimil Babka > Signed-off-by: David Hildenbrand Reviewed-by: Oscar Salvador -- Oscar Salvador SUSE L3