Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753936Ab3H0VeS (ORCPT ); Tue, 27 Aug 2013 17:34:18 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:41487 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751835Ab3H0VeR (ORCPT ); Tue, 27 Aug 2013 17:34:17 -0400 Date: Tue, 27 Aug 2013 14:34:15 -0700 From: Andrew Morton To: Wanpeng Li Cc: Chen Gong , Andi Kleen , Fengguang Wu , Tony Luck , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/3] mm/hwpoison: fix return value of madvise_hwpoison Message-Id: <20130827143415.fa284d67f0ae838079b5a5aa@linux-foundation.org> In-Reply-To: <521c5ddd.c9fc440a.2724.ffff8c70SMTPIN_ADDED_BROKEN@mx.google.com> References: <1377571171-9958-1-git-send-email-liwanp@linux.vnet.ibm.com> <1377571171-9958-3-git-send-email-liwanp@linux.vnet.ibm.com> <1377574096-y8hxgzdw-mutt-n-horiguchi@ah.jp.nec.com> <521c1f3f.813d320a.6ba7.5a17SMTPIN_ADDED_BROKEN@mx.google.com> <1377574896-5k1diwl4-mutt-n-horiguchi@ah.jp.nec.com> <20130827073701.GA23035@gchen.bj.intel.com> <521c5ddd.c9fc440a.2724.ffff8c70SMTPIN_ADDED_BROKEN@mx.google.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3006 Lines: 88 On Tue, 27 Aug 2013 16:02:29 +0800 Wanpeng Li wrote: > Hi Chen, > On Tue, Aug 27, 2013 at 03:37:01AM -0400, Chen Gong wrote: > >> On Tue, Aug 27, 2013 at 11:38:27AM +0800, Wanpeng Li wrote: > >> > Hi Naoya, > >> > On Mon, Aug 26, 2013 at 11:28:16PM -0400, Naoya Horiguchi wrote: > >> > >On Tue, Aug 27, 2013 at 10:39:31AM +0800, Wanpeng Li wrote: > >> > >> The return value outside for loop is always zero which means madvise_hwpoison > >> > >> return success, however, this is not truth for soft_offline_page w/ failure > >> > >> return value. > >> > > > >> > >I don't understand what you want to do for what reason. Could you clarify > >> > >those? > >> > > >> > int ret is defined in two place in madvise_hwpoison. One is out of for > >> > loop and its value is always zero(zero means success for madvise), the > >> > other one is in for loop. The soft_offline_page function maybe return > >> > -EBUSY and break, however, the ret out of for loop is return which means > >> > madvise_hwpoison success. > >> > >> Oh, I see. Thanks. > >> > >I don't think such change is a good idea. The original code is obviously > >easy to confuse people. Why not removing redundant local variable? > > > > I think the trick here is get_user_pages_fast will return the number of > pages pinned. It is always 1 in madvise_hwpoison, the return value of > memory_failure is ignored. Therefore we still need to reset ret to 0 > before return madvise_hwpoison. erk, madvise_hwpoison() has two locals with the same name. Bad. From: Andrew Morton Subject: mm/madvise.c:madvise_hwpoison(): remove local `ret' madvise_hwpoison() has two locals called "ret". Fix it all up. Cc: Wanpeng Li Cc: Naoya Horiguchi Cc: Andi Kleen Signed-off-by: Andrew Morton --- mm/madvise.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff -puN mm/madvise.c~a mm/madvise.c --- a/mm/madvise.c~a +++ a/mm/madvise.c @@ -343,15 +343,16 @@ static long madvise_remove(struct vm_are */ static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end) { - int ret = 0; - if (!capable(CAP_SYS_ADMIN)) return -EPERM; for (; start < end; start += PAGE_SIZE) { struct page *p; - int ret = get_user_pages_fast(start, 1, 0, &p); + int ret; + + ret = get_user_pages_fast(start, 1, 0, &p); if (ret != 1) return ret; + if (PageHWPoison(p)) { put_page(p); continue; @@ -369,7 +370,7 @@ static int madvise_hwpoison(int bhv, uns /* Ignore return value for now */ memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED); } - return ret; + return 0; } #endif _ -- 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/