From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752935AbdBTMgQ (ORCPT ); Mon, 20 Feb 2017 07:36:16 -0500 Received: from mx2.suse.de ([195.135.220.15]:42918 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752520AbdBTMgP (ORCPT ); Mon, 20 Feb 2017 07:36:15 -0500 Date: Mon, 20 Feb 2017 13:35:50 +0100 From: Michal Hocko To: Maxime Ripard Cc: Rob Herring , Mark Rutland , Chen-Yu Tsai , Greg Kroah-Hartman , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, Thomas Petazzoni , Joonsoo Kim , m.szyprowski@samsung.com Subject: Re: [PATCH 3/8] mm: cma: Export a few symbols Message-ID: <20170220123550.GH2431@dhcp22.suse.cz> References: <2dee6c0baaf08e2c7d48ceb7e97e511c914d0f87.1486655917.git-series.maxime.ripard@free-electrons.com> <20170209192046.GB31906@dhcp22.suse.cz> <20170213134416.akgmtv3lv5m65fwx@lukather> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170213134416.akgmtv3lv5m65fwx@lukather> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 13-02-17 14:44:16, Maxime Ripard wrote: > Hi Michal, > > On Thu, Feb 09, 2017 at 08:20:47PM +0100, Michal Hocko wrote: > > [CC CMA people] > > > > On Thu 09-02-17 17:39:17, Maxime Ripard wrote: > > > Modules might want to check their CMA pool size and address for debugging > > > and / or have additional checks. > > > > > > The obvious way to do this would be through dev_get_cma_area and > > > cma_get_base and cma_get_size, that are currently not exported, which > > > results in a build failure. > > > > > > Export them to prevent such a failure. > > > > Who actually uses those exports. None of the follow up patches does > > AFAICS. > > This is for the ARM Mali GPU driver that is out of tree, unfortunately. We do not export symbols which do not have any in-tree users. > In one case (using the legacy fbdev API), the driver wants to (and > probably should) validate that the buffer as indeed been allocated > from the memory allocation pool. > > Rob suggested that instead of hardcoding it to cover the whole RAM > (which defeats the purpose of that check in the first place), we used > the memory-region bindings in the DT and follow that, which does work > great, but we still have to retrieve the base address and size of that > region, hence why this patches are needed. Anyway I would suggest talking to CMA people to find a better API for modules to use... -- Michal Hocko SUSE Labs