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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 27F2FC38A29 for ; Sat, 18 Apr 2020 14:41:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 043942224E for ; Sat, 18 Apr 2020 14:41:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587220918; bh=isVRNvQT2EACdfwVZ9k/k4qA8as+uSSfDwj793vYOTM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=x1CXTkgGtulg0Ihu/pchIr7XAIEj9aBIGNDBFkD4ljnaguY2/iUL2qCATYB6dxZVH LohU4uW4LnTgr0LFn0A7O0UJRmQ9kcX3lBA31tRmPQOKMg0KBYO8g4co5mdwcDQynM ZPtDe+BbmO8gpVN7SSPuSk7jS+ukYWpoIEmObERg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728196AbgDROl4 (ORCPT ); Sat, 18 Apr 2020 10:41:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:51416 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728107AbgDROlv (ORCPT ); Sat, 18 Apr 2020 10:41:51 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1844321D7E; Sat, 18 Apr 2020 14:41:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587220910; bh=isVRNvQT2EACdfwVZ9k/k4qA8as+uSSfDwj793vYOTM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NjNcH/32wqeQpu0L5g5eY89JRM21ooL9KPLcXJfdltixK0T1ldyIfvRB2p1FCdR81 u+44Pxtzg/OEbN9zdcC1YHa6OMXVDO6LoEqUyLTIPMpAcytDPKACXBlW9zn47tAyvf HL4XRXCkGEoksy3dlTBHEljxdV6h31z2vRSqOPi0= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jiri Olsa , Peter Zijlstra , Ingo Molnar , Sasha Levin Subject: [PATCH AUTOSEL 5.4 50/78] perf/core: Disable page faults when getting phys address Date: Sat, 18 Apr 2020 10:40:19 -0400 Message-Id: <20200418144047.9013-50-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200418144047.9013-1-sashal@kernel.org> References: <20200418144047.9013-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jiri Olsa [ Upstream commit d3296fb372bf7497b0e5d0478c4e7a677ec6f6e9 ] 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 Signed-off-by: Sasha Levin --- 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 15b123bdcaf53..72d0cfd73cf11 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6537,9 +6537,12 @@ 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); -- 2.20.1