From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754508AbbCBOXh (ORCPT ); Mon, 2 Mar 2015 09:23:37 -0500 Received: from mga02.intel.com ([134.134.136.20]:43339 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753148AbbCBOXg (ORCPT ); Mon, 2 Mar 2015 09:23:36 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,675,1418112000"; d="scan'208";a="673880322" From: kan.liang@intel.com To: acme@redhat.com Cc: linux-kernel@vger.kernel.org, xiakaixu@huawei.com, a.p.zijlstra@chello.nl, ak@linux.intel.com, Kan Liang Subject: [PATCH 1/1] Revert "perf: Remove the extra validity check on nr_pages" Date: Mon, 2 Mar 2015 02:14:26 -0500 Message-Id: <1425280466-7830-1-git-send-email-kan.liang@intel.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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! 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