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=-9.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 18DCAC4332D for ; Tue, 2 Mar 2021 20:14:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C895D64F2A for ; Tue, 2 Mar 2021 20:14:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1836291AbhCBUIO (ORCPT ); Tue, 2 Mar 2021 15:08:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1580135AbhCBRaZ (ORCPT ); Tue, 2 Mar 2021 12:30:25 -0500 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CBC8C0617A7 for ; Tue, 2 Mar 2021 09:29:21 -0800 (PST) Received: by mail-pj1-x102e.google.com with SMTP id l18so2477513pji.3 for ; Tue, 02 Mar 2021 09:29:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=3aMc27tpAIEfKlaleQ63UwE+oQiX3xp96PGjmghrhTg=; b=iUwjJGNfPxHb9Lk8qYHVrPWUX+3s+sN3sTys7j387re1W2aHHgvnCu+5BErtGgbufa 8yLRV+PZVRpkXCcVfwcm3pvpK3yZA/ID0YyAYYFumfgYbizl7E2JSojdq/FTtZr2cNZv z4jN+B5NNg8v4XzwXFH5TePq93QtmtkYJdPGFN7Iugt30e7toqDSUnC5tIg7LmEQsLc5 2A+8WMf95zaUxlk33oPgSG/7TlEjiSxH1YPbZMhqL/rhOcygTvIL0Rrc+/E6ndoIO6ef jcDKy/nLnsDodMZj+GuykGbXTYx9gkVpjxct6XAW5txZujQAaq/01PdvS/Cx9CwKeErm eJsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=3aMc27tpAIEfKlaleQ63UwE+oQiX3xp96PGjmghrhTg=; b=rZ0gw3zu5g+SiKblw0OjpJqxLxDhtaTixT9/snXFWEVfKBdZk0YXgUcaW1sOpQvS5t mXorid5MLpdhgm6UuH7Vk+KTQ6RHAjWvh3KhiRzve/kak+QU7NuKSQQsV2GYWjVVUON+ byJOdbQ2tzzfVzUXNrQUxE7mGGXATf5n/pc/xadp650J2M94cfa+JcG8RduksHXWqgXB f32gda68Q2emiU2uIrqG+s/dRx3OnTCFmW4gNr8LeB0Q2F5uXjfRnkEtc4SmsIX0HGk/ GDRitFD8Wt/GWRfxlPWE2UsQ0rE3UN0MeUR7lAPGhS6MBdygoe+cUyy2r3b00SPygh/L PnuA== X-Gm-Message-State: AOAM532E1gGDsc81g3u+RBFFxcl8UOkQLZH1S3sNnCBbYVAzm1d1U4SL rVU8xGvfKhEJk6V2vm2Nguw= X-Google-Smtp-Source: ABdhPJwo06XEcbjKhcPToXinlb0dWl2XGRjySi5KIHLpgZ1P0zL/Tw34MyTvOh8jXZ32KZOSz+3fOw== X-Received: by 2002:a17:902:8697:b029:e3:9724:e260 with SMTP id g23-20020a1709028697b02900e39724e260mr4460941plo.31.1614706161096; Tue, 02 Mar 2021 09:29:21 -0800 (PST) Received: from google.com ([2620:15c:211:201:297a:af1:8ccf:6094]) by smtp.gmail.com with ESMTPSA id b188sm23106282pfg.179.2021.03.02.09.29.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Mar 2021 09:29:20 -0800 (PST) Sender: Minchan Kim Date: Tue, 2 Mar 2021 09:29:18 -0800 From: Minchan Kim To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Oscar Salvador , Michal Hocko , 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, 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 I agree it's not useful to dump just range. Rather than, dump_page would be much helpful. Acked-by: Minchan Kim