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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 163FBC352A4 for ; Mon, 10 Feb 2020 13:10:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DA54520708 for ; Mon, 10 Feb 2020 13:10:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581340237; bh=tQYTd3Uh9Z2rSv3L6HeVSik4uQnzOeEVHMU0da33i0I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=sAdXaPy9bxCbr6sxeDd6YxRu0hXFe0oRiRZdeYDauSjV8bVZCyovlISxCHuExG40J EkjZolNbElpIhv8+c/9dLCevb58e6fnsebeDebqgKU2dK+JZlIlhsN7k64YBxVTJ7B A/ZVpPENLHQJQj9I7sIniCU4luorBHO7U5BRWdN0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730467AbgBJNKf (ORCPT ); Mon, 10 Feb 2020 08:10:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:36252 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728087AbgBJMjK (ORCPT ); Mon, 10 Feb 2020 07:39:10 -0500 Received: from localhost (unknown [209.37.97.194]) (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 07A8C2080C; Mon, 10 Feb 2020 12:39:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581338349; bh=tQYTd3Uh9Z2rSv3L6HeVSik4uQnzOeEVHMU0da33i0I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=glq98QcpW9RqZbAclauqASx8aFLITsPiaIu7yCTNTov9CKiwh96/jZ95sIkEtFApy ae44UnDRmX8F8L1aTDPMN5jtwlnQpz7yfoKoXU5qxa32a99TRvHLZ92HjLbLOosKrp +OV+MEjKYITxfWHpJsKlhf28SZNQkwReUh0CktbI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Shishkin , Song Liu , "Peter Zijlstra (Intel)" , Ingo Molnar Subject: [PATCH 5.4 306/309] perf/core: Fix mlock accounting in perf_mmap() Date: Mon, 10 Feb 2020 04:34:22 -0800 Message-Id: <20200210122436.377300557@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200210122406.106356946@linuxfoundation.org> References: <20200210122406.106356946@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: Song Liu commit 003461559ef7a9bd0239bae35a22ad8924d6e9ad upstream. Decreasing sysctl_perf_event_mlock between two consecutive perf_mmap()s of a perf ring buffer may lead to an integer underflow in locked memory accounting. This may lead to the undesired behaviors, such as failures in BPF map creation. Address this by adjusting the accounting logic to take into account the possibility that the amount of already locked memory may exceed the current limit. Fixes: c4b75479741c ("perf/core: Make the mlock accounting simple again") Suggested-by: Alexander Shishkin Signed-off-by: Song Liu Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Cc: Acked-by: Alexander Shishkin Link: https://lkml.kernel.org/r/20200123181146.2238074-1-songliubraving@fb.com Signed-off-by: Greg Kroah-Hartman --- kernel/events/core.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5823,7 +5823,15 @@ accounting: */ user_lock_limit *= num_online_cpus(); - user_locked = atomic_long_read(&user->locked_vm) + user_extra; + user_locked = atomic_long_read(&user->locked_vm); + + /* + * sysctl_perf_event_mlock may have changed, so that + * user->locked_vm > user_lock_limit + */ + if (user_locked > user_lock_limit) + user_locked = user_lock_limit; + user_locked += user_extra; if (user_locked <= user_lock_limit) { /* charge all to locked_vm */