Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759802Ab3EAWcO (ORCPT ); Wed, 1 May 2013 18:32:14 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:43547 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759209Ab3EAWcL (ORCPT ); Wed, 1 May 2013 18:32:11 -0400 Message-ID: <518197E2.7050004@linux.vnet.ibm.com> Date: Wed, 01 May 2013 15:32:02 -0700 From: Cody P Schafer User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: David Rientjes CC: Andrew Morton , Linux MM , LKML Subject: Re: [PATCH 1/4] mmzone: make holding lock_memory_hotplug() a requirement for updating pgdat size References: <1367446635-12856-1-git-send-email-cody@linux.vnet.ibm.com> <1367446635-12856-2-git-send-email-cody@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13050122-7408-0000-0000-00000FB7B14D Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1218 Lines: 31 On 05/01/2013 03:26 PM, David Rientjes wrote: > On Wed, 1 May 2013, Cody P Schafer wrote: > >> All updaters of pgdat size (spanned_pages, start_pfn, and >> present_pages) currently also hold lock_memory_hotplug() (in addition >> to pgdat_resize_lock()). >> >> Document this and make holding of that lock a requirement on the update >> side for now, but keep the pgdat_resize_lock() around for readers that >> can't lock a mutex. >> >> Signed-off-by: Cody P Schafer > > Nack, these fields are initialized at boot without lock_memory_hotplug(), > so you're statement is wrong, and all you need is pgdat_resize_lock(). They are also initialized at boot without pgdat_resize_lock(), if we consider boot time, quite a few of the statements on when locking is required are wrong. That said, you are correct that it is not strictly required to hold lock_memory_hotplug() when updating the fields in question because pgdat_resize_lock() is used. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/