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,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 916C9C2BA83 for ; Thu, 13 Feb 2020 15:54:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5B22C24676 for ; Thu, 13 Feb 2020 15:54:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581609263; bh=mPnSoR/YyvQL2wOzJz4i83uyE95FR0NBKs0Au3JO9XM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Mk1I4HiIEf5gZL31oyaxsN0CU5wvWR4yJAPFeGiAW1Mmiu61aK8Wyn9ZVRnC/CxjA 3wmA7velmzsfFMUwdd684kj0gbD3v75rmXI6fDvUdh0NMPxCyelhG2aawAiJskENUz eRGY7Ms+4IplpS1HjJ3NVDo9V0MFL/m+qZqd7uLk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388263AbgBMPyW (ORCPT ); Thu, 13 Feb 2020 10:54:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:42842 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728371AbgBMPZz (ORCPT ); Thu, 13 Feb 2020 10:25:55 -0500 Received: from localhost (unknown [104.132.1.104]) (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 90ACE24693; Thu, 13 Feb 2020 15:25:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581607554; bh=mPnSoR/YyvQL2wOzJz4i83uyE95FR0NBKs0Au3JO9XM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2CR4C+6RuC+eEzihfNcifoqGbo/Fdb/yT0LkCgDWIoVF6A+CfQlm7x0Fl7U0tYZj3 b4FSE8IHSyit5pvt67JInJrtsGBku8NKcTBRFUqv3BiN0C/viZ1RwcwQIsVcb4+YoU GVAyJTeAavNQwHrps51CYY45IQKjLYie02Ky6m/Y= 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 4.14 139/173] perf/core: Fix mlock accounting in perf_mmap() Date: Thu, 13 Feb 2020 07:20:42 -0800 Message-Id: <20200213152006.863124046@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200213151931.677980430@linuxfoundation.org> References: <20200213151931.677980430@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 @@ -5441,7 +5441,15 @@ 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) extra = user_locked - user_lock_limit;