From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f50.google.com (mail-pa0-f50.google.com [209.85.220.50]) by kanga.kvack.org (Postfix) with ESMTP id 28D2F6B0036 for ; Mon, 28 Jul 2014 19:24:16 -0400 (EDT) Received: by mail-pa0-f50.google.com with SMTP id et14so11304208pad.37 for ; Mon, 28 Jul 2014 16:24:15 -0700 (PDT) Received: from mga02.intel.com (mga02.intel.com. [134.134.136.20]) by mx.google.com with ESMTP id lm5si19282362pab.182.2014.07.28.16.24.14 for ; Mon, 28 Jul 2014 16:24:15 -0700 (PDT) Message-ID: <53D6DB9C.7030109@intel.com> Date: Mon, 28 Jul 2014 16:24:12 -0700 From: Dave Hansen MIME-Version: 1.0 Subject: Re: [PATCH] memory hotplug: update the variables after memory removed References: <1406550617-19556-1-git-send-email-zhenzhang.zhang@huawei.com> <53D642E5.2010305@huawei.com> <53D6685C.1060509@intel.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Zhang Zhen , shaohui.zheng@intel.com, mgorman@suse.de, mingo@redhat.com, Linux MM , linux-kernel@vger.kernel.org, wangnan0@huawei.com, akpm@linux-foundation.org On 07/28/2014 04:12 PM, David Rientjes wrote: > I agree, but I'm not sure the suggestion is any better than the patch. I > think it would be better to just figure out whether anything needs to be > updated in the caller and then call a generic function. > > So in arch_add_memory(), do > > end_pfn = PFN_UP(start + size); > if (end_pfn > max_pfn) > update_end_of_memory_vars(end_pfn); > > and in arch_remove_memory(), > > end_pfn = PFN_UP(start); > if (end_pfn < max_pfn) > update_end_of_memory_vars(end_pfn); > > and then update_end_of_memory_vars() becomes a three-liner. That does look better than my suggestion, generally. It is broken in the remove case, though. In your example, the memory being removed is assumed to be coming from the end of memory, and that isn't always the case. I think you need something like: if ((max_pfn >= start_pfn) && (max_pfn < end_pfn) update_end_of_memory_vars(start); But, yeah, that's a lot better than new functions. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org