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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C6774C433DB for ; Mon, 1 Mar 2021 15:53:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 737F864DF2 for ; Mon, 1 Mar 2021 15:53:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237459AbhCAPxX (ORCPT ); Mon, 1 Mar 2021 10:53:23 -0500 Received: from mx2.suse.de ([195.135.220.15]:58172 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237394AbhCAPxV (ORCPT ); Mon, 1 Mar 2021 10:53:21 -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=1614613950; 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=J8aNPfcrByRMnbgjPkO4YD4mA4esidLDQxdZhSdcPUE=; b=BtmPBL9eZIBj17BSbuu8ZnGI06iA3+Rs6WmNS+GygDjx/RLHRj7VrE0HBdFqugSOWCfZqh uWY5xM6V344UgKDZOrBhooX+HiN7pKxTbo/Vd3iH2d1aIa64peclLR6XiJRyZ77xe7c2Kw DO0P3WuaeoDNGLTdEj4umY2M0CTAaW4= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 12E7EAF54; Mon, 1 Mar 2021 15:52:30 +0000 (UTC) Date: Mon, 1 Mar 2021 16:52:28 +0100 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Minchan Kim , Oscar Salvador , Vlastimil Babka Subject: Re: [PATCH v1] mm/page_alloc: drop pr_info_ratelimited() in alloc_contig_range() Message-ID: 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 01-03-21 16:09:45, 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 Acked-by: Michal Hocko > --- > mm/page_alloc.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 519a60d5b6f7..efb924fb13e8 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8647,8 +8647,6 @@ int alloc_contig_range(unsigned long start, unsigned long end, > > /* Make sure the range is really isolated. */ > if (test_pages_isolated(outer_start, end, 0)) { > - pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n", > - __func__, outer_start, end); > ret = -EBUSY; > goto done; > } > -- > 2.29.2 -- Michal Hocko SUSE Labs