From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755719AbeAHU3z (ORCPT + 1 other); Mon, 8 Jan 2018 15:29:55 -0500 Received: from mail-it0-f51.google.com ([209.85.214.51]:37563 "EHLO mail-it0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755603AbeAHU3x (ORCPT ); Mon, 8 Jan 2018 15:29:53 -0500 X-Google-Smtp-Source: ACJfBotbSfHfQz0+8FXV42qWT0wPYk2Oh/u+iIcrp+MHxkXcFB2VACwNZnI2JS15WkOvlbPJPIghRQ== From: Vince Weaver X-Google-Original-From: Vince Weaver Date: Mon, 8 Jan 2018 15:29:42 -0500 (EST) X-X-Sender: vince@macbook-air To: Ingo Molnar cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo Subject: Re: perf: perf_fuzzer quickly locks up on 4.15-rc7 In-Reply-To: <20180108173005.lkglqrixb2ota6g2@gmail.com> Message-ID: References: <20180108173005.lkglqrixb2ota6g2@gmail.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Mon, 8 Jan 2018, Ingo Molnar wrote: > > Note that the page table isolation (PTI) feature has a number of effects on perf > and on NMI handlers, so one of the things to try would be to disable PTI. Yes, it seems to be a KPTI issue. With KPTI disabled I can fuzz for a few hours, no problems. With KPTI enabled the perf_fuzzer on this haswell machine will lock up within minutes. It's a hard lockup with nothing over the serial console. It is not deterministic/reproducible either. Vince