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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 A3221C43463 for ; Sun, 20 Sep 2020 20:49:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 679AA20866 for ; Sun, 20 Sep 2020 20:49:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726178AbgITUt1 (ORCPT ); Sun, 20 Sep 2020 16:49:27 -0400 Received: from mout.kundenserver.de ([212.227.17.24]:59005 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726126AbgITUt1 (ORCPT ); Sun, 20 Sep 2020 16:49:27 -0400 Received: from mail-qt1-f182.google.com ([209.85.160.182]) by mrelayeu.kundenserver.de (mreue109 [212.227.15.145]) with ESMTPSA (Nemesis) id 1N8XHb-1kWs4J3JmT-014Ptw; Sun, 20 Sep 2020 22:49:23 +0200 Received: by mail-qt1-f182.google.com with SMTP id g3so10564365qtq.10; Sun, 20 Sep 2020 13:49:21 -0700 (PDT) X-Gm-Message-State: AOAM533FAqUmi9ggyBgk95+0qEs9x8sjXEEQE6YM9b/GmWlH5oFml7xM tQFQtTWGHBUJ+ZKkulQ0J5mbPHkWHrsIJ3/Vf1A= X-Google-Smtp-Source: ABdhPJwBXwBil3iRHV11f3BxYsgRD++l69TenwTYSqKgYe+2Dux9TFUrSKvqlq1FFlXpzrttVMSzDz47tEK6RfJnMjg= X-Received: by 2002:aed:2ce5:: with SMTP id g92mr30020804qtd.204.1600634960428; Sun, 20 Sep 2020 13:49:20 -0700 (PDT) MIME-Version: 1.0 References: <20200918124533.3487701-1-hch@lst.de> <20200918124533.3487701-2-hch@lst.de> <20200920151510.GS32101@casper.infradead.org> <20200920180742.GN3421308@ZenIV.linux.org.uk> <20200920190159.GT32101@casper.infradead.org> <20200920191031.GQ3421308@ZenIV.linux.org.uk> <20200920192259.GU32101@casper.infradead.org> In-Reply-To: From: Arnd Bergmann Date: Sun, 20 Sep 2020 22:49:03 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag To: Andy Lutomirski Cc: Matthew Wilcox , Al Viro , Christoph Hellwig , Andrew Morton , Jens Axboe , David Howells , linux-arm-kernel , X86 ML , LKML , "open list:MIPS" , Parisc List , linuxppc-dev , linux-s390 , sparclinux , linux-block , Linux SCSI List , Linux FS Devel , linux-aio , io-uring@vger.kernel.org, linux-arch , Linux-MM , Network Development , keyrings@vger.kernel.org, LSM List Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:CVl0ZST0kq+ZM8bIyVy4buxByYewwVWTGaSQX2cG7S+fxfOLfg4 3IYQ1WP9vOXA8wRJwMcZrEPB4//duV8Ezeyis3yGi12DLKgs/AttJWnePBnn8Tp2+uaC/ge glaUSs0pf4QOVqQCS3dbPqrr+HVUhs3EVO6/ZQWS1fjn9MdptiKjtHzdDpBD3MOE+/lqWn4 qrZAlLdnkVWlRVBK6p/Xg== X-UI-Out-Filterresults: notjunk:1;V03:K0:f3fveQ4ykwA=:KAthfX0nOA+uyVgjLJ5kAm +/NVDftUAleKVGB39k3aR+WDoJXnKOKr6t0aNGpkuqe7jfEq/uGu2lDt3nAOfF8VCbJPOf4sD EgLD/hnHr9RytPu/kIn5l/M3EBZ8RMtiJ1xJQZNflulbXLsBTwNWmmZ8iZ6gB6DuAOUBSBxSC t853woJyRuBR5tuswbZynFfuGe33fG3jbhQK7yAXsaw9n7fUE0xDXyYvaZCdUz8xqATZDqjey nYZQbfbxA4yMlNPr70CtwEsRXZfZeS1qFqGeT43XWfVwEWJi2jjBUEMh4JhQ21IT5k7O+EobU kGGbTkmhquG64kwlsXoOIPQrgEv7h40navwp6Hox2SlcjftISGtvKG5O/CcTZ1vU4HX/HvuHC kFKPhyT89sDque3Fz2CYyKS24aoMJMsiee2bPj12K0A1+lSil9cIuWHnhrgHHYwgzFDFNtLC0 WyJH63cIEgohAbXtU9AmMhBTOAYK2MBtu5WarlG36VJyxmIEXBsEi8AiU6DMZrkNB7rKhw0SH g7tVgijFac4tF/ImrUh3277u2SPu3b+aCRqOSlL6ujCW6QJNhZT6bEH0UzrVkMQOPe8RX4mqd 3Q3/xiTMKfaOWNw4LpD2G3oAnrxTrvMVK64rlvlguG9O2vzugecMZ1ODciPfxq+rXPGyAfJRu pLeh2aR8vSevKSlkxmTUYkCNXe8vIwxrPDZQZuIOzVaJqVxHH4NzxwbWjk5IyiiV3590nWd2f UB4Gj65iTtx5p/d2Mv52pqinXBPIOrh02+jFufA90d1Pj9Az9vPqOY5Df2zY2LWHaUsBZXxB0 BqJAswtSXAA97rNNoyP5162ODXNDLV8UHH0m6k/E9vkD8feGqKIjajwGStAE1k0b1BXWEin Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Sun, Sep 20, 2020 at 9:28 PM Andy Lutomirski wrote: > On Sun, Sep 20, 2020 at 12:23 PM Matthew Wilcox wrote: > > > > On Sun, Sep 20, 2020 at 08:10:31PM +0100, Al Viro wrote: > > > IMO it's much saner to mark those and refuse to touch them from io_uring... > > > > Simpler solution is to remove io_uring from the 32-bit syscall list. > > If you're a 32-bit process, you don't get to use io_uring. Would > > any real users actually care about that? > > We could go one step farther and declare that we're done adding *any* > new compat syscalls :) Would you also stop adding system calls to native 32-bit systems then? On memory constrained systems (less than 2GB a.t.m.), there is still a strong demand for running 32-bit user space, but all of the recent Arm cores (after Cortex-A55) dropped the ability to run 32-bit kernels, so that compat mode may eventually become the primary way to run Linux on cheap embedded systems. I don't think there is any chance we can realistically take away io_uring from the 32-bit ABI any more now. Arnd