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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,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 59F92C2D0EA for ; Wed, 8 Apr 2020 12:20:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3423F2087E for ; Wed, 8 Apr 2020 12:20:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728253AbgDHMU1 (ORCPT ); Wed, 8 Apr 2020 08:20:27 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:49623 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727666AbgDHMU0 (ORCPT ); Wed, 8 Apr 2020 08:20:26 -0400 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jM9gt-00062k-F9; Wed, 08 Apr 2020 14:20:23 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 773D01C0131; Wed, 8 Apr 2020 14:20:21 +0200 (CEST) Date: Wed, 08 Apr 2020 12:20:21 -0000 From: "tip-bot2 for Jiri Olsa" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/urgent] perf/core: Disable page faults when getting phys address Cc: Peter Zijlstra , Jiri Olsa , Ingo Molnar , x86 , LKML In-Reply-To: <20200407141427.3184722-1-jolsa@kernel.org> References: <20200407141427.3184722-1-jolsa@kernel.org> MIME-Version: 1.0 Message-ID: <158634842102.28353.10574957272961464103.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the perf/urgent branch of tip: Commit-ID: d3296fb372bf7497b0e5d0478c4e7a677ec6f6e9 Gitweb: https://git.kernel.org/tip/d3296fb372bf7497b0e5d0478c4e7a677ec6f6e9 Author: Jiri Olsa AuthorDate: Tue, 07 Apr 2020 16:14:27 +02:00 Committer: Ingo Molnar CommitterDate: Wed, 08 Apr 2020 11:33:46 +02:00 perf/core: Disable page faults when getting phys address We hit following warning when running tests on kernel compiled with CONFIG_DEBUG_ATOMIC_SLEEP=y: WARNING: CPU: 19 PID: 4472 at mm/gup.c:2381 __get_user_pages_fast+0x1a4/0x200 CPU: 19 PID: 4472 Comm: dummy Not tainted 5.6.0-rc6+ #3 RIP: 0010:__get_user_pages_fast+0x1a4/0x200 ... Call Trace: perf_prepare_sample+0xff1/0x1d90 perf_event_output_forward+0xe8/0x210 __perf_event_overflow+0x11a/0x310 __intel_pmu_pebs_event+0x657/0x850 intel_pmu_drain_pebs_nhm+0x7de/0x11d0 handle_pmi_common+0x1b2/0x650 intel_pmu_handle_irq+0x17b/0x370 perf_event_nmi_handler+0x40/0x60 nmi_handle+0x192/0x590 default_do_nmi+0x6d/0x150 do_nmi+0x2f9/0x3c0 nmi+0x8e/0xd7 While __get_user_pages_fast() is IRQ-safe, it calls access_ok(), which warns on: WARN_ON_ONCE(!in_task() && !pagefault_disabled()) Peter suggested disabling page faults around __get_user_pages_fast(), which gets rid of the warning in access_ok() call. Suggested-by: Peter Zijlstra Signed-off-by: Jiri Olsa Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lkml.kernel.org/r/20200407141427.3184722-1-jolsa@kernel.org --- kernel/events/core.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 26de0a5..bc9b98a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6934,9 +6934,12 @@ static u64 perf_virt_to_phys(u64 virt) * Try IRQ-safe __get_user_pages_fast first. * If failed, leave phys_addr as 0. */ - if ((current->mm != NULL) && - (__get_user_pages_fast(virt, 1, 0, &p) == 1)) - phys_addr = page_to_phys(p) + virt % PAGE_SIZE; + if (current->mm != NULL) { + pagefault_disable(); + if (__get_user_pages_fast(virt, 1, 0, &p) == 1) + phys_addr = page_to_phys(p) + virt % PAGE_SIZE; + pagefault_enable(); + } if (p) put_page(p);