From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7D84C282C4 for ; Wed, 13 Feb 2019 01:40:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7396B2190A for ; Wed, 13 Feb 2019 01:40:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733133AbfBMBkL (ORCPT ); Tue, 12 Feb 2019 20:40:11 -0500 Received: from mga05.intel.com ([192.55.52.43]:17068 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727458AbfBMBkK (ORCPT ); Tue, 12 Feb 2019 20:40:10 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Feb 2019 17:40:08 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,364,1544515200"; d="scan'208";a="124043653" Received: from yjin15-mobl.ccr.corp.intel.com (HELO [10.239.159.76]) ([10.239.159.76]) by fmsmga008.fm.intel.com with ESMTP; 12 Feb 2019 17:40:06 -0800 Subject: Re: [PATCH] perf/core: don't WARN for impossible rb sizes To: Peter Zijlstra Cc: Mark Rutland , linux-kernel@vger.kernel.org, julien.thierry@arm.com, Alexander Shishkin , Ingo Molnar , Jiri Olsa , Namhyung Kim , "Jin, Yao" , Arnaldo Carvalho de Melo References: <20190110142745.25495-1-mark.rutland@arm.com> <1f71da66-4783-0108-668c-cdffca499719@linux.intel.com> <20190212130756.GH32494@hirez.programming.kicks-ass.net> From: "Jin, Yao" Message-ID: <023208e9-4aec-3401-8ec1-6368a01df8f7@linux.intel.com> Date: Wed, 13 Feb 2019 09:40:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190212130756.GH32494@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/12/2019 9:07 PM, Peter Zijlstra wrote: > On Tue, Feb 12, 2019 at 10:42:38AM +0800, Jin, Yao wrote: >>> diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c >>> index 4a9937076331..309ef5a64af5 100644 >>> --- a/kernel/events/ring_buffer.c >>> +++ b/kernel/events/ring_buffer.c >>> @@ -734,6 +734,9 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags) >>> size = sizeof(struct ring_buffer); >>> size += nr_pages * sizeof(void *); >>> + if (order_base_2(size) >= MAX_ORDER) >>> + goto fail; >>> + >>> rb = kzalloc(size, GFP_KERNEL); > > Yes, Boris also send the entire morning bisecting this. > > The problem is that @size is in bytes and MAX_ORDER is in pages. > > That should be: > > if (order_base_2(size) >= PAGE_SHIFT+MAX_ORDER) > > Thanks Peter! This fix works! Thanks Jin Yao