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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,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 44C89ECDE4B for ; Thu, 8 Nov 2018 22:02:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C46720817 for ; Thu, 8 Nov 2018 22:02:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="SEYy1Gvg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0C46720817 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731132AbeKIHkZ (ORCPT ); Fri, 9 Nov 2018 02:40:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:60034 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727045AbeKIHkY (ORCPT ); Fri, 9 Nov 2018 02:40:24 -0500 Received: from localhost (unknown [208.72.13.198]) (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 380DC2081C; Thu, 8 Nov 2018 22:02:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541714575; bh=SPQbLxBUBiwLXvCblOMvQCVQc2Wt0MF+3/zrJQD765Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SEYy1Gvgxh42KaE59w8hmJAfR44MpQbcWd/rFEJphu+5PRM/Z3vbVz+kjDsQ7NP5T d3Q95YfLCUU8RfnlrJtWFzBJwS+8kGNQAXsu0yV/J7Z8WtnJdwXYI0E2K8/Vh5SRUh MaeoXVhuV1eqVf7EtdJusxSFDkpL5zR/zGi7+sog= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jiri Olsa , "Peter Zijlstra (Intel)" , Alexander Shishkin , Andrew Vagin , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Jiri Olsa , Linus Torvalds , Namhyung Kim , Stephane Eranian , Thomas Gleixner , Vince Weaver , Ingo Molnar , Sasha Levin Subject: [PATCH 4.9 027/171] perf/ring_buffer: Prevent concurent ring buffer access Date: Thu, 8 Nov 2018 13:49:57 -0800 Message-Id: <20181108215129.257622004@linuxfoundation.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181108215127.257643509@linuxfoundation.org> References: <20181108215127.257643509@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review 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 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit cd6fb677ce7e460c25bdd66f689734102ec7d642 ] Some of the scheduling tracepoints allow the perf_tp_event code to write to ring buffer under different cpu than the code is running on. This results in corrupted ring buffer data demonstrated in following perf commands: # perf record -e 'sched:sched_switch,sched:sched_wakeup' perf bench sched messaging # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 0.383 [sec] [ perf record: Woken up 8 times to write data ] 0x42b890 [0]: failed to process type: -1765585640 [ perf record: Captured and wrote 4.825 MB perf.data (29669 samples) ] # perf report --stdio 0x42b890 [0]: failed to process type: -1765585640 The reason for the corruption are some of the scheduling tracepoints, that have __perf_task dfined and thus allow to store data to another cpu ring buffer: sched_waking sched_wakeup sched_wakeup_new sched_stat_wait sched_stat_sleep sched_stat_iowait sched_stat_blocked The perf_tp_event function first store samples for current cpu related events defined for tracepoint: hlist_for_each_entry_rcu(event, head, hlist_entry) perf_swevent_event(event, count, &data, regs); And then iterates events of the 'task' and store the sample for any task's event that passes tracepoint checks: ctx = rcu_dereference(task->perf_event_ctxp[perf_sw_context]); list_for_each_entry_rcu(event, &ctx->event_list, event_entry) { if (event->attr.type != PERF_TYPE_TRACEPOINT) continue; if (event->attr.config != entry->type) continue; perf_swevent_event(event, count, &data, regs); } Above code can race with same code running on another cpu, ending up with 2 cpus trying to store under the same ring buffer, which is specifically not allowed. This patch prevents the problem, by allowing only events with the same current cpu to receive the event. NOTE: this requires the use of (per-task-)per-cpu buffers for this feature to work; perf-record does this. Signed-off-by: Jiri Olsa [peterz: small edits to Changelog] Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Andrew Vagin Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Fixes: e6dab5ffab59 ("perf/trace: Add ability to set a target task for events") Link: http://lkml.kernel.org/r/20180923161343.GB15054@krava Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/events/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 95bd00d9f2c3..3caf1a863a0b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7737,6 +7737,8 @@ void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size, goto unlock; list_for_each_entry_rcu(event, &ctx->event_list, event_entry) { + if (event->cpu != smp_processor_id()) + continue; if (event->attr.type != PERF_TYPE_TRACEPOINT) continue; if (event->attr.config != entry->type) -- 2.17.1