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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_GIT 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 ADDFFC43219 for ; Fri, 3 May 2019 08:55:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82EA62075C for ; Fri, 3 May 2019 08:55:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726632AbfECIzn (ORCPT ); Fri, 3 May 2019 04:55:43 -0400 Received: from mga18.intel.com ([134.134.136.126]:31447 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726138AbfECIzn (ORCPT ); Fri, 3 May 2019 04:55:43 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 May 2019 01:55:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,425,1549958400"; d="scan'208";a="321087550" Received: from black.fi.intel.com (HELO black.fi.intel.com.) ([10.237.72.28]) by orsmga005.jf.intel.com with ESMTP; 03 May 2019 01:55:40 -0700 From: Alexander Shishkin To: Peter Zijlstra Cc: Arnaldo Carvalho de Melo , Ingo Molnar , linux-kernel@vger.kernel.org, jolsa@redhat.com, adrian.hunter@intel.com, Alexander Shishkin Subject: [PATCH 0/2] perf: Fix AUX software double buffering Date: Fri, 3 May 2019 11:55:34 +0300 Message-Id: <20190503085536.24119-1-alexander.shishkin@linux.intel.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, There was a problem with 04fe30a61514 ("perf/ring_buffer: Use high order allocations for AUX buffers optimistically") that made buffers that were previously scattered across multiple pages into one large buffer, breaking double buffering. In practice, this manifests easily for non-privileged users, whose buffers are generally smaller than MAX_ORDER and would fit into one high-order allocation. Root's default AUX buffer size is larger and would get split, so they are less affected. The fix is trivial and we also get rid of one PMU capability as a bonus. Alexander Shishkin (2): perf: Fix AUX software double buffering perf, pt: Remove software double buffering PMU capability arch/x86/events/intel/pt.c | 3 +-- include/linux/perf_event.h | 1 - kernel/events/ring_buffer.c | 3 +-- 3 files changed, 2 insertions(+), 5 deletions(-) -- 2.20.1