From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx105.postini.com [74.125.245.105]) by kanga.kvack.org (Postfix) with SMTP id B12CB6B005A for ; Sat, 28 Jul 2012 02:09:06 -0400 (EDT) Received: by obhx4 with SMTP id x4so6732299obh.14 for ; Fri, 27 Jul 2012 23:09:05 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1343411703-2720-1-git-send-email-js1304@gmail.com> <1343411703-2720-4-git-send-email-js1304@gmail.com> Date: Sat, 28 Jul 2012 15:09:05 +0900 Message-ID: Subject: Re: [RESEND PATCH 4/4 v3] mm: fix possible incorrect return value of move_pages() syscall From: JoonSoo Kim Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Brice Goglin , Minchan Kim 2012/7/28 Christoph Lameter : > On Sat, 28 Jul 2012, Joonsoo Kim wrote: > >> move_pages() syscall may return success in case that >> do_move_page_to_node_array return positive value which means migration failed. > > Nope. It only means that the migration for some pages has failed. This may > still be considered successful for the app if it moves 10000 pages and one > failed. > > This patch would break the move_pages() syscall because an error code > return from do_move_pages_to_node_array() will cause the status byte for > each page move to not be updated anymore. Application will not be able to > tell anymore which pages were successfully moved and which are not. In case of returning non-zero, valid status is not required according to man page. So, this patch would not break the move_pages() syscall. But, I agree that returning positive value only means that the migration for some pages has failed. This is my mistake, so please drop this patch. Thanks for review. -- 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