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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B00FEC7EE29 for ; Thu, 8 Jun 2023 10:52:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236204AbjFHKw0 (ORCPT ); Thu, 8 Jun 2023 06:52:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235116AbjFHKwE (ORCPT ); Thu, 8 Jun 2023 06:52:04 -0400 Received: from mail-oi1-x235.google.com (mail-oi1-x235.google.com [IPv6:2607:f8b0:4864:20::235]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39A5230F6 for ; Thu, 8 Jun 2023 03:51:36 -0700 (PDT) Received: by mail-oi1-x235.google.com with SMTP id 5614622812f47-39a3f2668d5so323502b6e.1 for ; Thu, 08 Jun 2023 03:51:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shopee.com; s=shopee.com; t=1686221494; x=1688813494; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=Ps3xEBUlTo7f8loMCsGDyMpKyduVCzzLK5zLOAo2FgA=; b=Kag095czxCEU7vOdxKYZ/d98TyXJFonRNM16ghzk2PL20EnQiixiPr/iWa2l47tliV XkK2Rb5wLA9XE+C70klonvxLrh1G87LUxWiGl/fVQBaXJaRuSMDXdDyvDNhk0lwtZZYR UcO8IQH2bctkoF24qDUkRYolVPAAuiqnEu6h2El5B+9dr0rlHZiB9AnM8CjfC6ELmr2Z AhqLj1MbQEmyJjq4L4Vy0nISNYXu8gf/9pEWSFFOZZYA5J+qLzDmXijxrwX6dRqTOc1v 4R9tw2hDnepnF0pRQqSW4aHVn2Z58L3HNVhU/OyC+xhgmDhHKi6AfZhTPuTefdy0TTzA MCQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686221494; x=1688813494; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=Ps3xEBUlTo7f8loMCsGDyMpKyduVCzzLK5zLOAo2FgA=; b=j/qBND4U6+UW95HbLaKNqCDsfI3ZwYwUCYY2rscP3ISHltLr5cS6B7rYXc3UeoA5wj SMbgt7dvUEImVHw4TfPx6Bx5BHyG4L2NrP1NPqwTFrDz1PvKGfmUgFhlgPlnRO/KLg3o Rm0fEvvXGCkAgUcZNiamyZOTPV4vb09IOBcCc/FEvsDJh2k512l6UChnincveTtBLYnL ftM/3MMqqZktwK46KURNty8lf7BK/3Bt1YY+O+cY0vojjRTtrO5WeFZAGlWagwOG9lTs sswxykm+8kwwsS+waQEdRuDxYk4ygJ8D79MBZ1JJgfmdfCevoepMQb7WEF7gq9c3Zxdk gVag== X-Gm-Message-State: AC+VfDwIsA6Er6viG4FT60eg35zadDkm4acDsiZQVcnozs/OEUkBBrjD sf1B1//73zh5S+JyppdMdJkvtA== X-Google-Smtp-Source: ACHHUZ72N291wzl0vYRQgKoDRSxdlp+HNwZWEHyWBr30AaBo6mZsWxlOZiVzilpKC0RImlSen5qXSw== X-Received: by 2002:a54:450a:0:b0:39a:b7a3:7d5e with SMTP id l10-20020a54450a000000b0039ab7a37d5emr4820536oil.33.1686221494459; Thu, 08 Jun 2023 03:51:34 -0700 (PDT) Received: from [10.54.24.10] ([143.92.118.3]) by smtp.gmail.com with ESMTPSA id b15-20020a17090a010f00b00256799877ffsm1059500pjb.47.2023.06.08.03.51.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Jun 2023 03:51:34 -0700 (PDT) Message-ID: Date: Thu, 8 Jun 2023 18:51:30 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: Re: [PATCH] mm/mm_init.c: add debug messsge for dma zone To: Mike Rapoport , Michal Hocko Cc: David Hildenbrand , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230607090734.1259-1-haifeng.xu@shopee.com> <34f32148-24c3-09a3-8bec-9515139e15b1@shopee.com> <20230608101340.GI52412@kernel.org> From: Haifeng Xu In-Reply-To: <20230608101340.GI52412@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/6/8 18:13, Mike Rapoport wrote: > On Thu, Jun 08, 2023 at 11:18:02AM +0200, Michal Hocko wrote: >> On Thu 08-06-23 15:38:48, Haifeng Xu wrote: >>> >>> >>> On 2023/6/7 18:22, David Hildenbrand wrote: >>>> On 07.06.23 12:16, Michal Hocko wrote: >>>>> On Wed 07-06-23 09:07:34, Haifeng Xu wrote: >>>>>> If freesize is less than dma_reserve, print warning message to report >>>>>> this case. >>>>> >>>>> Why? >>>> >>>> I'd like to second that question, and add >>>> >>>> a) Did you run into that scenario? >>>> b) What can an admin do in that case with that error messages? >>> >>> In theory，dma_reserve shouldn't exceed freesize, so the error messages can remind us >>> to verify whether the configuration of reserved memory is correct. >> >> I am not really convinced this is worth touching the code TBH. > > The only architecture that sets the dma_reserve is x86_64 and it sets it to > the number of reserved pages in DMA zone. There is no way freesize will be > less than dma_reserve. Yes. From the comments, x86_64 calculates the dma_reserve in order to set zone watermarks more accurately. But berfore init_per_zone_wmark_min(), memblock_free_all() has already recalculated the managed pages. It seems that the dma_reserve is not really helpful to this. > > I'm not sure that in general dma_reserve has some value now, but that's a > completely different story. > >> -- >> Michal Hocko >> SUSE Labs >