From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757049Ab3LERNq (ORCPT ); Thu, 5 Dec 2013 12:13:46 -0500 Received: from comal.ext.ti.com ([198.47.26.152]:60602 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757028Ab3LERNp (ORCPT ); Thu, 5 Dec 2013 12:13:45 -0500 Message-ID: <52A0B42C.5080405@ti.com> Date: Thu, 5 Dec 2013 12:13:16 -0500 From: Santosh Shilimkar User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Tejun Heo CC: Grygorii Strashko , , , , Yinghai Lu , Andrew Morton Subject: Re: [PATCH v2 08/23] mm/memblock: Add memblock memory allocation apis References: <1386037658-3161-1-git-send-email-santosh.shilimkar@ti.com> <1386037658-3161-9-git-send-email-santosh.shilimkar@ti.com> <20131203232445.GX8277@htj.dyndns.org> <529F5047.50309@ti.com> <20131204160730.GQ3158@htj.dyndns.org> <529F5C55.1020707@ti.com> <52A07BBE.7060507@ti.com> <20131205165936.GB24062@mtj.dyndns.org> In-Reply-To: <20131205165936.GB24062@mtj.dyndns.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 05 December 2013 11:59 AM, Tejun Heo wrote: > Hello, > > On Thu, Dec 05, 2013 at 03:12:30PM +0200, Grygorii Strashko wrote: >> I'll try to provide more technical details here. >> As Santosh mentioned in previous e-mails, it's not easy to simply >> get rid of using MAX_NUMNODES: >> 1) we introduce new interface memblock_allocX >> 2) our interface uses memblock APIs __next_free_mem_range_rev() >> and __next_free_mem_range() >> 3) __next_free_mem_range_rev() and __next_free_mem_range() use MAX_NUMNODES >> 4) _next_free_mem_range_rev() and __next_free_mem_range() are used standalone, >> outside of our interface as part of *for_each_free_mem_range* or for_each_mem_pfn_range .. >> >> The point [4] leads to necessity to find and correct all places where memmblock APIs >> are used and where it's expected to get MAX_NUMNODES as input parameter. >> The major problem is that simple "grep" will not work, because memmblock APIs calls >> are hidden inside other MM modules and it's not always clear >> what will be passed as input parameters to APIs of these MM modules >> (for example sparse_memory_present_with_active_regions() or sparse.c). > > Isn't that kinda trivial to work around? Make those functions accept > both MAX_NUMNODES and NUMA_NO_NODE but emit warning on MAX_NUMNODES > (preferably throttled reasonably). Given the history of API, we'd > probably want to keep such warning for extended period of time but > that's what we'd need to do no matter what. > Looks a good idea. >> As result, WIP patch, I did, and which was posted by Santosh illustrates >> the probable size and complexity of the change. > > Again, I don't really mind the order things happen but I don't think > it's a good idea to spread misusage with a new API. You gotta deal > with it one way or the other. > >> Sorry, but question here is not "Do or not to do?", but rather 'how to do?", >> taking into account complexity and state of the current MM code. >> For example. would it be ok if I'll workaround the issue as in the attached patch? > > Well, it's more of when. It's not really a technically difficult > task and all I'm saying is it better be sooner than later. > Fair enough. Based on your suggestion, we will try to see if we can proceed with 4) accepting both MAX_NUMNODES and NUMA_NO_NODE. Thanks for the suggestion. regards, Santosh