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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 66CF5C4727E for ; Wed, 30 Sep 2020 12:30:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 083962071E for ; Wed, 30 Sep 2020 12:30:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="MvP7h294" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729757AbgI3MaE (ORCPT ); Wed, 30 Sep 2020 08:30:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725776AbgI3MaD (ORCPT ); Wed, 30 Sep 2020 08:30:03 -0400 Received: from mail-qk1-x741.google.com (mail-qk1-x741.google.com [IPv6:2607:f8b0:4864:20::741]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77316C061755 for ; Wed, 30 Sep 2020 05:30:03 -0700 (PDT) Received: by mail-qk1-x741.google.com with SMTP id x201so1129099qkb.11 for ; Wed, 30 Sep 2020 05:30:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=pIB/BrnCARLplACqwVj4jzjc3q+0k51FVNXxV4ATL1Q=; b=MvP7h294xIEbRHpFMRAX5vBZbkFqX2uFaWtrhCH6eX4KSMS97KAXAyzrEK9Y7dAk97 d1uxAZNy/tuonY70eOgM1fZWbPqoeBYIavErYPCC7+FKagXuF7XNmBYGw6QQfdOjpmOi 809awPQYYMG/MuwcBs8wWJslB81H0ivECWC0DoUSrpphZGPYX83LuP320LWXV5aiFsHu 2lQsbIkXsp67vfIgWZU0kefMmfdtqS+CFe3cA7ILCU1kEEWHKoAbf02NAEDTQCozWjV3 JHaa3/S+SpW375p7xJ7mBvlHh15RjIquOGbLI2c33cKvs1ywJ6pOHKT5z83WOX4FazI3 C0VA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=pIB/BrnCARLplACqwVj4jzjc3q+0k51FVNXxV4ATL1Q=; b=R2L263I+q9URXxBdfG5KUiYq8ggRBQttVqfm4T/nTBSrKnukSH4Q0NoBZBGRMG+gQq orCJ3kWCapOaCTmWbeTRsCsfXM62HW6g3Z+m9obfSQnHEXdoNi4H6Qi4lHtiDX34YI45 lUB8lZe8/k/+lO6kNNshEOuqbIwS+ySfqxqZZog/Yd63wZmfEy6pi8bvplmCMGohqsOS 1IwZSQUU2B0srWsgfjWDHLkI3C+3QDeVBbtB4dXu0byx39pyl85duXoyBvn9tmMrLaqs owfTkX7I0Q9Mzm/qG4dWatcD2p17UvaqgFWs4fvhyVXT371m7gq1asZc6J/tKDUaD49o rA7A== X-Gm-Message-State: AOAM530NhilBk+Hf9aHiD9qMXYGGydd1XIeskSYkGXkmA1MdP9RlZRyw 2pjOR4h3rSJD9plsCZIMnWCdMg== X-Google-Smtp-Source: ABdhPJy/rI7ioygbhkFzpvP77x46x3rVWfmjQBGcdZUXw4jxZDfPULCzx7I+MFCan2zB+xWmpExw5A== X-Received: by 2002:a37:9301:: with SMTP id v1mr2372108qkd.350.1601469002489; Wed, 30 Sep 2020 05:30:02 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-156-34-48-30.dhcp-dynamic.fibreop.ns.bellaliant.net. [156.34.48.30]) by smtp.gmail.com with ESMTPSA id 196sm1857233qkm.49.2020.09.30.05.30.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Sep 2020 05:30:01 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kNbFA-003w5a-MC; Wed, 30 Sep 2020 09:30:00 -0300 Date: Wed, 30 Sep 2020 09:30:00 -0300 From: Jason Gunthorpe To: Jann Horn Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Eric W . Biederman" , Michel Lespinasse , Mauro Carvalho Chehab , Sakari Ailus Subject: Re: [PATCH 3/4] mmap locking API: Don't check locking if the mm isn't live yet Message-ID: <20200930123000.GC9916@ziepe.ca> References: <20200930011944.19869-1-jannh@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 On Tue, Sep 29, 2020 at 06:20:00PM -0700, Jann Horn wrote: > In preparation for adding a mmap_assert_locked() check in > __get_user_pages(), teach the mmap_assert_*locked() helpers that it's fine > to operate on an mm without locking in the middle of execve() as long as > it hasn't been installed on a process yet. I'm happy to see lockdep being added here, but can you elaborate on why add this mmap_locked_required instead of obtaining the lock in the execv path? Jason