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 A38BEC7EE25 for ; Thu, 8 Jun 2023 10:14:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235518AbjFHKO0 (ORCPT ); Thu, 8 Jun 2023 06:14:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236023AbjFHKON (ORCPT ); Thu, 8 Jun 2023 06:14:13 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 127CB2D54 for ; Thu, 8 Jun 2023 03:14:07 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8987064BBE for ; Thu, 8 Jun 2023 10:14:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 84C5BC433EF; Thu, 8 Jun 2023 10:14:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686219246; bh=A/yf/LULqe7cvpY9FNQQv9+HJYr9a5XLS/1CEJh4cUI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YCr1Wl0YP84wvIO2VnanRSDJFX8gKazY0fIbIaQQpeY8GwiC4hJKVKNwtW0q4LCzf t93zJ1seq5bE9yZRw83p/S4eY8irVRPlLZHE4zT70ZBfYBB8OH/X3eb29hyfK3F353 XbqPetAS+vr27HRFX6ytssh7f8WeSAZBa142EB+1TSWnufkB3VYtvjcFHm/6n9j9GZ jczUfeXFIjQA7EBXdX7DCGVMTVFYZ+tnHcgOjGY6svebxlSssNpgVxMIwRUPbwu7Dc NLTXt4JHsFOjeQllk02r4Aoh9kBaJnSVJN2MLSjmPTVdPELaClUG4Na86StyoAV/Jw Vnae3p4wKE9HA== Date: Thu, 8 Jun 2023 13:13:40 +0300 From: Mike Rapoport To: Michal Hocko Cc: Haifeng Xu , David Hildenbrand , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/mm_init.c: add debug messsge for dma zone Message-ID: <20230608101340.GI52412@kernel.org> References: <20230607090734.1259-1-haifeng.xu@shopee.com> <34f32148-24c3-09a3-8bec-9515139e15b1@shopee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. I'm not sure that in general dma_reserve has some value now, but that's a completely different story. > -- > Michal Hocko > SUSE Labs -- Sincerely yours, Mike.