From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx138.postini.com [74.125.245.138]) by kanga.kvack.org (Postfix) with SMTP id 25C6A6B005A for ; Tue, 17 Jul 2012 11:41:10 -0400 (EDT) Received: by obhx4 with SMTP id x4so993929obh.14 for ; Tue, 17 Jul 2012 08:41:09 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1342528415-2291-1-git-send-email-js1304@gmail.com> <1342528415-2291-2-git-send-email-js1304@gmail.com> Date: Wed, 18 Jul 2012 00:41:08 +0900 Message-ID: Subject: Re: [PATCH 2/4 v2] mm: fix possible incorrect return value of migrate_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, Sasha Levin 2012/7/17 Christoph Lameter : > On Tue, 17 Jul 2012, Joonsoo Kim wrote: > >> @@ -1382,6 +1382,8 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode, >> >> err = do_migrate_pages(mm, old, new, >> capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE); >> + if (err > 0) >> + err = -EBUSY; >> >> mmput(mm); >> out: > > Why not have do_migrate_pages() return EBUSY if we do not need the number > of failed/retried pages? There is no serious reason. do_migrate_pages() have two callsites, although another one doesn't use return value. do_migrate_pages() is commented "Return the number of page ...". And my focus is fixing possible error in migrate_pages() syscall. So, I keep to return the number of failed/retired pages. If we really think the number of failed/retired pages is useless, in that time, instead that do_migrate_pages() return EBUSY, we can make migrate_pages() return EBUSY. I think it is better to fix all the related codes at one go. -- 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