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=-9.0 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=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 674A1C43381 for ; Mon, 1 Apr 2019 17:33:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 37F182070B for ; Mon, 1 Apr 2019 17:33:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554140009; bh=AZZmrHyeLP9V+hKISCkPEYCYz3uXYeKNMK8LvDw59cM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=V6x1PUm/pRZgkLaOcibX7KBgduMoyNQTHOZntTTjwfQIBzNJvpe9sHJH4jMb/qJOM elJohlZmnApe7+DLcoycPT9+A5vhnwwtfwZu9h6OYjD+tC2hDqF7e/nvzAYISoaFNg NYlEOuQIe0U+h/zTHssiVqIt549I1u0zbuYFJuas= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387628AbfDARd1 (ORCPT ); Mon, 1 Apr 2019 13:33:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:42290 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387616AbfDARdX (ORCPT ); Mon, 1 Apr 2019 13:33:23 -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 3B0C820830; Mon, 1 Apr 2019 17:33:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554140002; bh=AZZmrHyeLP9V+hKISCkPEYCYz3uXYeKNMK8LvDw59cM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q5oRfqwQiLIQ/GHDi9ag58TFzqrdMQEXtBs9VLCay/1xQpOx2pn+mJANePliytFvw Rau9vA8q6pkH0VFAzwSjbfcDtenguDmyjZxF7ry+KwVAc9rP7H/2/LPSZa3TyMSvBe 7n9XlEXKMFtPV4/UOazdpbGnKvx04bPEmtQ4Uef0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Shishkin , "Peter Zijlstra (Intel)" , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Jiri Olsa , Linus Torvalds , Stephane Eranian , Thomas Gleixner , Vince Weaver , vince@deater.net, Ingo Molnar , Sasha Levin Subject: [PATCH 4.4 076/131] perf/ring_buffer: Refuse to begin AUX transaction after rb->aux_mmap_count drops Date: Mon, 1 Apr 2019 19:02:26 +0200 Message-Id: <20190401170058.429119601@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190401170051.645954551@linuxfoundation.org> References: <20190401170051.645954551@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore 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 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit dcb10a967ce82d5ad20570693091139ae716ff76 ] When ring buffer's AUX area is unmapped and rb->aux_mmap_count drops to zero, new AUX transactions into this buffer can still be started, even though the buffer in en route to deallocation. This patch adds a check to perf_aux_output_begin() for rb->aux_mmap_count being zero, in which case there is no point starting new transactions, in other words, the ring buffers that pass a certain point in perf_mmap_close will not have their events sending new data, which clears path for freeing those buffers' pages right there and then, provided that no active transactions are holding the AUX reference. Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: vince@deater.net Link: http://lkml.kernel.org/r/1457098969-21595-2-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/events/ring_buffer.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 94dc6b0763ab..7324d83d6bd8 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -288,6 +288,13 @@ void *perf_aux_output_begin(struct perf_output_handle *handle, if (!rb_has_aux(rb) || !atomic_inc_not_zero(&rb->aux_refcount)) goto err; + /* + * If rb::aux_mmap_count is zero (and rb_has_aux() above went through), + * the aux buffer is in perf_mmap_close(), about to get freed. + */ + if (!atomic_read(&rb->aux_mmap_count)) + goto err; + /* * Nesting is not supported for AUX area, make sure nested * writers are caught early -- 2.19.1