From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755508AbbBLKYc (ORCPT ); Thu, 12 Feb 2015 05:24:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39230 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755441AbbBLKYa (ORCPT ); Thu, 12 Feb 2015 05:24:30 -0500 From: Vitaly Kuznetsov To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , "K. Y. Srinivasan" , Haiyang Zhang , Andrew Morton , Yasuaki Ishimatsu , Tang Chen , Vlastimil Babka , David Rientjes , Fabian Frederick , Zhang Zhen , Vladimir Davydov , Wang Nan , "Rafael J. Wysocki" , devel@linuxdriverproject.org, linux-mm@kvack.org Subject: [PATCH RESEND 2/3] memory_hotplug: add note about holding device_hotplug_lock and add_memory() Date: Thu, 12 Feb 2015 11:23:53 +0100 Message-Id: <1423736634-338-3-git-send-email-vkuznets@redhat.com> In-Reply-To: <1423736634-338-1-git-send-email-vkuznets@redhat.com> References: <1423736634-338-1-git-send-email-vkuznets@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org add_memory() is supposed to be run with device_hotplug_lock grabbed, otherwise it can race with e.g. device_online(). ACPI memory hotplug does that already but e.g. Hyper-V ballooning driver doesn't. Signed-off-by: Vitaly Kuznetsov --- mm/memory_hotplug.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 9fab107..41638eb 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1213,7 +1213,11 @@ int zone_for_memory(int nid, u64 start, u64 size, int zone_default) return zone_default; } -/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */ +/* + * NOTE: The caller must call lock_device_hotplug() to serialize hotplug + * and online/offline operations before this call. + * We are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG. + */ int __ref add_memory(int nid, u64 start, u64 size) { pg_data_t *pgdat = NULL; -- 1.9.3