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=-4.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 375C0C64E7B for ; Wed, 2 Dec 2020 23:31:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC3DD217A0 for ; Wed, 2 Dec 2020 23:31:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387453AbgLBXbl (ORCPT ); Wed, 2 Dec 2020 18:31:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726819AbgLBXbk (ORCPT ); Wed, 2 Dec 2020 18:31:40 -0500 Received: from mail-qt1-x842.google.com (mail-qt1-x842.google.com [IPv6:2607:f8b0:4864:20::842]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67564C0613D6 for ; Wed, 2 Dec 2020 15:31:00 -0800 (PST) Received: by mail-qt1-x842.google.com with SMTP id k4so93898qtj.10 for ; Wed, 02 Dec 2020 15:31:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=MZKIHGtuA3gRLQDXNr6MTzyQShpkGxfy4iPg0ZnOpJc=; b=HVZIZtD7by3oSo0VHfJUYl2rMpEQ2VLQwynmJg1HQ4JT/6WJb0AdIwABIY4nzMXNin 8BZmRdybGi9r3NTYAfthPpt932sR7oaxa8IVdtKyx705UfvayJezzRBF5zgBJ6ZpBSjq kfPTVEelC1MIWLsXZnCJGPQyyI7SOICJ+JZk+Yt55j1zEBvugHMUXpddK3A/4WaA8X27 egtzSVL00FZ5ujVnrK8wcHoqA8DiyIhjuOUipA8PPPEfrZJjoWn1Kk4eWqBvUNw7Qjmj MW4mO3omJ6+4PCJBBZPqnGIqeo649OBjAqVC9VIyupGFNLADyVxe5oFzGt6v5O9ITyz2 XSng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=MZKIHGtuA3gRLQDXNr6MTzyQShpkGxfy4iPg0ZnOpJc=; b=Qa5iP5zPeqMVtUewubZq2RJ4bEhZtnUgxvU+Yz4ICw7vtfb20liCP636Ix73RLsHpL baRwZnl1jUmWXH0YoPJsHWq/IbTcHDhoDFOnpzkNfrYu5kFqlMCtCflxLIVXcSb6LeGf vlRbRWS1ODDho2RKrvctO1+yvkrzmUOhZ7TeftnLjN2ZjQyG9FqKm66AtLUUvlQ5FXXY R48rT2ynQqx8I1lKU5bDwcmR1JROJompVw6p/juB7wJWemCUxdND+DWd2RAsKlrbNeq+ YyXlglbSAKB3KyhvAKFFx6lDnpVQ4K7DRL8heVwlLSnP/EWZ124f3F2jbcsO0U0rTVTH IYHQ== X-Gm-Message-State: AOAM531ws4MWc6zmQsw5OibdJHOm6aH5jkzRmfRvJ97/mvdoQnAEvZKq t9pbmitwuGivhj6qm+sXPL8= X-Google-Smtp-Source: ABdhPJzAKfrCry46Ge063OA0b5tvAqqwcRbzSeuc423xyKkyYGnaSvDDQkHJLsA80KnF3SrK+WwiCw== X-Received: by 2002:ac8:75da:: with SMTP id z26mr650437qtq.36.1606951859531; Wed, 02 Dec 2020 15:30:59 -0800 (PST) Received: from localhost ([2620:10d:c091:480::1:ec0f]) by smtp.gmail.com with ESMTPSA id o16sm219958qkg.27.2020.12.02.15.30.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Dec 2020 15:30:58 -0800 (PST) Sender: Tejun Heo Date: Wed, 2 Dec 2020 18:30:30 -0500 From: Tejun Heo To: Shakeel Butt Cc: Axel Rasmussen , Greg Thelen , Andrew Morton , Chinwen Chang , Daniel Jordan , David Rientjes , Davidlohr Bueso , Ingo Molnar , Jann Horn , Laurent Dufour , Michel Lespinasse , Stephen Rothwell , Steven Rostedt , Vlastimil Babka , Yafang Shao , "David S . Miller" , dsahern@kernel.org, Greg Kroah-Hartman , Jakub Kicinski , liuhangbin@gmail.com, LKML , Linux MM Subject: Re: [PATCH] mm: mmap_lock: fix use-after-free race and css ref leak in tracepoints Message-ID: References: <20201130233504.3725241-1-axelrasmussen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Dec 02, 2020 at 03:23:57PM -0800, Shakeel Butt wrote: > > There've been some changes to cgroup ids recently and now cgroup id, ino and > > its file_handle are all compatible. On 64bit ino machines, they're all the > > same and won't be reused. On 32bit ino machines, the lower 32bit of full id > > is used as ino. ino may be reused but not the full 64bit id. > > __kernfs_new_node() is using idr_alloc_cyclic() which will return > 32bit ID. If I am understanding this correctly the full ID is > generated similarly for 32bit and 64bit machines but for 64bit > machines the whole ID is inode number while on 32bit machines the > lower 32bits contains the inode number. Is that correct? Yes, that's correct. Thanks. -- tejun