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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,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 2168BC83004 for ; Tue, 28 Apr 2020 18:57:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFA65206D6 for ; Tue, 28 Apr 2020 18:57:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588100252; bh=LJPNTG9+CksbqGWw/Lw0H/aPHnvQKgLfs3lHpxgohkI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Jl8Avt1VOsilk16cb/WF9ACLsrHXjttTkEzMupIcd6/RKyJKKHsN62FRGwhV5lFNF YILihc5ZkKfzGakZrN7BLTJV8XhfmEHba44ISs/9rUEurtZtARlI9rYz8UVxpcigbO QIi5Ojyx0bqLhXenqQ+ulNv2tyvkjjsbdrVLl6M0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729537AbgD1S5b (ORCPT ); Tue, 28 Apr 2020 14:57:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:45042 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729491AbgD1SaW (ORCPT ); Tue, 28 Apr 2020 14:30:22 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6DE9F2076A; Tue, 28 Apr 2020 18:30:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588098621; bh=LJPNTG9+CksbqGWw/Lw0H/aPHnvQKgLfs3lHpxgohkI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ofhWtR5qzdFtMnB0haR+s6JV0dzbfnNPPERlBXm3vMl82OXucIfZczWw24YbBps2k nUF/C866P+0z8HrUlqHoA2m6wuKRRUcZ27sYrZh+axr7Zi64LN6pwgksOHNBFdUASr WTjU0uBS4Hp9BGg6X9KS/ECeDRtiJHvzOCiWRu7w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Zijlstra , Jiri Olsa , Ingo Molnar , Sasha Levin Subject: [PATCH 4.19 029/131] perf/core: Disable page faults when getting phys address Date: Tue, 28 Apr 2020 20:24:01 +0200 Message-Id: <20200428182228.805413119@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200428182224.822179290@linuxfoundation.org> References: <20200428182224.822179290@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 8c70ee23fbe91..00fb2fe92c4d6 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6411,9 +6411,12 @@ 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