From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753072AbeDKMEw (ORCPT ); Wed, 11 Apr 2018 08:04:52 -0400 Received: from mail-wm0-f53.google.com ([74.125.82.53]:35347 "EHLO mail-wm0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753041AbeDKMEv (ORCPT ); Wed, 11 Apr 2018 08:04:51 -0400 X-Google-Smtp-Source: AIpwx49LHq6zpogX9je0J4oap+KdaKZGBlvp/ACL8/AYqvRhFwZO6/D1X6Vo/GBVjOb5HiwYMziPAg== Date: Wed, 11 Apr 2018 14:04:47 +0200 From: Ingo Molnar To: Song Liu Cc: Vince Weaver , "linux-kernel@vger.kernel.org" , Peter Zijlstra Subject: Re: perf: fuzzer leads to trace_kprobe: Could not insert message flood Message-ID: <20180411120447.2gzrwijrtayjv3eg@gmail.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Song Liu wrote: > > > > On Apr 10, 2018, at 7:48 AM, Vince Weaver wrote: > > > > Author: Song Liu > > Date: Wed Dec 6 14:45:15 2017 -0800 > > > > When running the perf_fuzzer on a current git checkout my logs are flooded > > with messages such as this: > > [71487.869077] trace_kprobe: Could not insert probe at unknown+0: -22 > > [71488.174479] trace_kprobe: Could not insert probe at unknown+0: -22 > > > > Presumably this is due to the introduction of the perf_kprobe PMU in > > commit e12f03d7031a977356e3d7b75a68c2185ff8d155 > > Author: Song Liu > > Date: Wed Dec 6 14:45:15 2017 -0800 > > > > Is there a way to get this error disabled, or else rate-limited? > > > > Vince > > Hi Vince, > > Thanks for the report. > > This is a new API that creates probe together with perf_event_open(). Based on > my limited understanding of perf_fuzzer, it doesn't understand this API, and uses > it in an abnormal way. [...] Vince's point is valid: the kernel log should not be flooded with pointless messages as a response to user-space ABI uses ... Why is there a kernel log message at all, isn't an error returned? > [...] I would recommend perf_fuzzer to understand this new API and test it. > [...] This bug needs to be fixed: a new API must not effectively DoS fuzzing efforts by spamming the kernel log ... Thanks, Ingo