From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755435AbbCBVEX (ORCPT ); Mon, 2 Mar 2015 16:04:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53352 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755310AbbCBVEE (ORCPT ); Mon, 2 Mar 2015 16:04:04 -0500 Date: Mon, 2 Mar 2015 18:03:49 -0300 From: Arnaldo Carvalho de Melo To: kan.liang@intel.com Cc: Ingo Molnar , linux-kernel@vger.kernel.org, xiakaixu@huawei.com, a.p.zijlstra@chello.nl, ak@linux.intel.com Subject: Re: [PATCH 1/1] Revert "perf: Remove the extra validity check on nr_pages" Message-ID: <20150302210349.GA2289@redhat.com> References: <1425280466-7830-1-git-send-email-kan.liang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1425280466-7830-1-git-send-email-kan.liang@intel.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.20 (2009-12-10) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Mon, Mar 02, 2015 at 02:14:26AM -0500, kan.liang@intel.com escreveu: > From: Kan Liang > > This reverts commit 74390aa55678 ("perf: Remove the extra validity check > on nr_pages") > > nr_pages equals to number of pages - 1 in perf_mmap. So nr_pages = 0 is > valide. So the nr_pages != 0 && !is_power_of_2(nr_pages) are all > needed for checking. Otherwise, for example, perf test 6 failed. > perf test 6 > 6: x86 rdpmc test :Error: > mmap() syscall returned with (Invalid argument) > FAILED! Yeah, my bad, we need to revert this, its just on tip/perf/core, will put the revert in my next pull request, thanks for spotting this! - Arnaldo > Signed-off-by: Kan Liang > --- > kernel/events/core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 89f0f16..a83581c 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -4423,7 +4423,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) > * If we have rb pages ensure they're a power-of-two number, so we > * can do bitmasks instead of modulo. > */ > - if (!is_power_of_2(nr_pages)) > + if (nr_pages != 0 && !is_power_of_2(nr_pages)) > return -EINVAL; > > if (vma_size != PAGE_SIZE * (1 + nr_pages)) > -- > 1.8.3.1