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 B321EC43469 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 80DE420874 for ; Sun, 20 Sep 2020 20:49:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726221AbgITUt1 (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: linux-block@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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Date: Sun, 20 Sep 2020 20:49:03 +0000 Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag Message-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: 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: 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 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 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 27F4DC43465 for ; Sun, 20 Sep 2020 20:49:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5109B20758 for ; Sun, 20 Sep 2020 20:49:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5109B20758 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arndb.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7222F6B0093; Sun, 20 Sep 2020 16:49:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6D273900009; Sun, 20 Sep 2020 16:49:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 524B26B0093; Sun, 20 Sep 2020 16:49:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id 2BCC56B0095 for ; Sun, 20 Sep 2020 16:49:25 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id CE2C4180AD804 for ; Sun, 20 Sep 2020 20:49:24 +0000 (UTC) X-FDA: 77284630248.23.pet29_0b047802713f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin23.hostedemail.com (Postfix) with ESMTP id 98CFE37604; Sun, 20 Sep 2020 20:49:24 +0000 (UTC) X-HE-Tag: pet29_0b047802713f X-Filterd-Recvd-Size: 5099 Received: from mout.kundenserver.de (mout.kundenserver.de [212.227.126.134]) by imf30.hostedemail.com (Postfix) with ESMTP; Sun, 20 Sep 2020 20:49:23 +0000 (UTC) Received: from mail-qt1-f179.google.com ([209.85.160.179]) by mrelayeu.kundenserver.de (mreue010 [212.227.15.129]) with ESMTPSA (Nemesis) id 1Mj8a5-1kwCyS44m5-00fAoK; Sun, 20 Sep 2020 22:49:22 +0200 Received: by mail-qt1-f179.google.com with SMTP id e7so10556505qtj.11; Sun, 20 Sep 2020 13:49:21 -0700 (PDT) X-Gm-Message-State: AOAM530Pt3ysCmIWvvcpDsH/zIgRLmjh8wgnoYENWmd2NKM5aPfxzPCq w6Cuw2UmBWc9RyCb91UF3QZzpkWbjASgHdmxLOk= 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:dDM6e9irZhkOMLh8TV6WKKM8Y0fRsy4VQpijl6wFnE2hu+QQWAj oAS/BV1T6PGRzmQwRfyv8IXaqqh/GNwpVPjpMkud1u94ubIWMP7xWCGaE+16KansyrGT0eS 4mNN7O+IialjVwx+kOIjdaKMaaP5Pvck1N+GFc+VSuabUy1wQPqSWSIHaBMQ0jwKwfpLjGk tLI/vH7NkFy5aHYsqnytQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:uhtIU0Sa0jI=:8sOk5p0hNPBW9K97I/aPiH iOpe029l/Feiq2tD6QWipCAO3YGOHGEQPWxZHa+UgJIFiyOWyo60scdECRNeI2BLwKWpLObix sniwyrbXTEIGfrJK7ASO1xn3LTi94sSWr5HmubCKoo3PzNB5pkHDJQh4czoE5qmxq/W3bFRUn KYi64NhrD1zXzepr+8xNlczHbaZZwschAL9Ja1sKH8Elim5D1Ofd0whE85DdYKvQhqBkeNWCX LRhehyqDlxFpxt218h4qJHIZ0IhJejKaIbCx9S/3ihZ3dDYM9+9+P43jiTwRmIbbr2fcAZ3KX WE0i78OOesPCgRi1law5TT0amiVJKwMOpwk9OwOZjruvkEnSI/eOktD0iZbDdyCDjcLvoGHHL /IIsl8OK62aR9lD7EynN6aPHAOneKLxZ4hhUNRMMJD7sMsA5VB+2FlEoISQMZe0OSmFOWdsbT OcIkh+cN1KCPwzQKwyVMAcpN/4KajW1RNTedzyigVuZaBHnyQudCebGBBktRCn4irDXdElFsh YSJZa8FnE/KdKT/W/T4PZoS1H+2B8cHf5QPVsMN3n0Ey1CRfYOBev4KBbqKfFsSinTsoB5Dpw 7B0xt+3ru/zuL4Yj+xjNI/BOEiU26ddgkre7Gm4fkH64SuwaB78HWdyyjcTq2HbSt2aC82Gy8 W7R7J2sMlav4TeSnbY1c6ACB7Dc0PSC0Xg3MOACoJgmR+VZPcVVAHI6EiXTQbwSIo6VPASu/K xCk6OH9Z1sg0Yil0AJ/bW9hIcAlRAnRZhWmA13CrM5K/qZWD+/05dMT4RmXBHkD5QjonPpvGu zlenn3nqcwBaVg/ETdLS6/U1pB+FZVj5ba5yBkH//w6sb8/eModF4UoJmBthufMiyNvRHSR X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 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 6B70DC43463 for ; Sun, 20 Sep 2020 20:51:18 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5DA6C206E5 for ; Sun, 20 Sep 2020 20:51:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5DA6C206E5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arndb.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4Bvfqk2dSZzDqRv for ; Mon, 21 Sep 2020 06:51:14 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=arndb.de (client-ip=212.227.126.134; helo=mout.kundenserver.de; envelope-from=arnd@arndb.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=arndb.de Received: from mout.kundenserver.de (mout.kundenserver.de [212.227.126.134]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Bvfnj5VHCzDqcR for ; Mon, 21 Sep 2020 06:49:27 +1000 (AEST) Received: from mail-qt1-f174.google.com ([209.85.160.174]) by mrelayeu.kundenserver.de (mreue011 [212.227.15.129]) with ESMTPSA (Nemesis) id 1MtwIW-1kcbd73koG-00uHe9 for ; Sun, 20 Sep 2020 22:49:22 +0200 Received: by mail-qt1-f174.google.com with SMTP id h6so10585290qtd.6 for ; Sun, 20 Sep 2020 13:49:21 -0700 (PDT) X-Gm-Message-State: AOAM5313PUKFi3jYb3gIT3aig8u77eAY8IRKfFRzHIj0PLmfqkIU2x6V XiB97JjqB6+DQU+Sn9kmUpz/XJTffncomXlxzZs= 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 Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:tF9TCQw5lIg2NZZ07atGwdwzig7ixcDmZTV5roQ9LPJ1TtGCefg Vk1onuElp+7G+py8xGfjRSaIzJjk6rw8cEWxg3w/b/q/lUS/HE9lqdV110WiPaDCbLra4xo D0OLli1S+sR+q1hTs/YkOiw9REZKXL+UxeDwN7F6YEsfWDAINXlixrt4rpvKZk8cEZcQRGX 5LpToZLPlQn3ibGiCBOgA== X-UI-Out-Filterresults: notjunk:1;V03:K0:X2rR3gD86rs=:QHrX1a0kCRrKudyMYx+I1p hubGa4wIaipoUc3M6J366Zgws+mxWEJBTMET990oS7ng9Hf+d5MKIZmCAsJP2tqXo9YEoDkl0 BylvG9Dg0eeOxKv6nqx3pIq3Pcls1UYzuq9+R158lDxVLxU5ZLVYR/Se2VBgM4UjT5MvWEgiF ai/xZDU0lG9EIXYhGbwlKmyXYOuCpMi3KVyMlDZtwIjioYMOFjrhhGmUTAVS8Ju6NYTbwHJ4D imPUE9kXpQOVaPsX9KJ3hMOiXxfVPxpkoVovQHT0v7JbG2K72NxAfyRLamyZfg436NdtWTORa p5AMpmVrOZ+QJyL0/xSbf3c6dG7UaZTXDzOSsKtNmOxiezE4CVctQX/nRtbXQfB5DUBPpZvOh 6T062fIcdljZEKOLisoD0EoC6xOV+7yeLQnmBJPIxxUssru5vZBzgdOVdD46NRdnq7Va2PsIO NhFOWgs+M2f5Ieqa4v+VwqNG8bwRLDxQ0BPZA4dEuvpwDg20k046TYV8h409SHIr9E/4Sbjh6 yJo4Olt1Cpb56gCwT+PF46h1elNcTXY84xayYD7iGV4eJoA2A9Gw/JnPMarNp+ge83KP7KT10 iH+/gJge8d6gJhUt2s0P6JBa5TVQBJEu+1D4g61UvohDjPVHQFPket3BD54bPCI5beZw0ITA/ 2fuYs2M1fHtH4tPbcF2Y1GwdQae+4mTBJOBYVEFOpPlJYwFMgMZqA4Tnug8bh9sbIuhOAxiGs SAjjeLDAyaLoiygdv6mAxoXEEzn6xh/bB1GZ/r/eoo6ZCOXMa7aQgdPQJcz9s1r0twFjI2XAo Don6yhgtkFTm1GTAl8MSjzfo3Y4dzg9+nEdOH0+wRSDqIRAf9x7hRHaa7Y+IZ04N6jHngNE5R WZUc3h+lMN3/bIdLasqLAAqDmTRDqqlgO5Be9uSRRNocuQulYpyPysoMli4t2wNL8PKwrHqy5 cANLkXVtVRkrtBpLQYKn87u0MM3tzkczTB753OCE28BxqGqZlI9k+ X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-aio , "open list:MIPS" , David Howells , Linux-MM , keyrings@vger.kernel.org, sparclinux , Christoph Hellwig , linux-arch , linux-s390 , Linux SCSI List , X86 ML , Matthew Wilcox , linux-block , Al Viro , io-uring@vger.kernel.org, linux-arm-kernel , Jens Axboe , Parisc List , Network Development , LKML , LSM List , Linux FS Devel , Andrew Morton , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 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=-5.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 E20FCC43463 for ; Sun, 20 Sep 2020 20:51:12 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 821EC206E5 for ; Sun, 20 Sep 2020 20:51:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="JYQvisn0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 821EC206E5 Authentication-Results: mail.kernel.org; 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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 X-Provags-ID: V03:K1:CA/6eumLY1F/+YhWwPPLvVQKUC7flBRFxxJBlEZbnZk03ZKl+kw DinyTKQO5IYogH2DpgC5t3PrFaJJcblrTwJaN1TgQCaJHH31IO8+vM3LKTs4oCLq1eePc2K AwQxZvkuauylZQJJpKXeJUiW7JdHoUu/eOYjdeAqnEI4SKF9rCt2K8sbUCc365ELHOKRWm+ 9D3DGPDTRYt4JQvDUE/Fg== X-UI-Out-Filterresults: notjunk:1;V03:K0:8CgPXRjPNT0=:gVlcjw5oJl5DHZXCt0l58e CgFllWY7hNE7H6YZDjFaUysEHwd1y0GchaYa5+xklXOr8s/30KyltsmbAFZ+WMsS+lKicKlO1 VIM4wfbVIXBLdn3QEKYOQaG1ejPWzg8F54yjrfThnitQohyd5z+7EaSbDqxPccF2mNgif4loB QQiF3ZXvIzRe8XQGIbiS4LugRb7Y5YNngtwMVsCA4TEjq6E1Lj4Fvge/OqoMqSyUOY14ZFcBN O0/wT8NLX7D1Ew5yiqohhsqgwCGtJFHxit0JE5y62lKPAhPar6yjrNpGhv22NVyoPyINplRnn bCu3I9ot9eK+Ls9g8Li/tTp1/cmCBt11FKo/MFHc3cTiWXObYIunlTF2xTytSvPAJo6GOqMhk dWUL7BB3CvUzoyJVdDDp3MCfmgsshKq0D87nnlEdUrJcah/SZunBm4OTwzqc3790c2vcgLfCB HkaMRveYebnYVbXW+BXmS01EfHCTy7cZbYc3fyV1BDleasAPz4UVAx5fZQlwgVFWw5Dqq+R+O j1nfSmIFNt/h9b4wEoK4F8MaZ4NGlS9GGy1JQtFgU6nJjykZIB4tBr/fB94jYqgW6ckFj8JaZ x3rUltOYF2tLAPTOgXvvn0A8s+vjrRmoJIWoG5gW4uto6lAzQUBi47WN0GBeQnui/G+lq5yiU kAIi9LGwQBWRFN4c7Rqq7jpXN5hShw052rI3Ew7jV8Td+aeGXc92yEPbI5JtUfV2DP9f9m25Z wiRpckM7YjbxBRv1Vh5qEaCpj1IMSljR4w//9gCqgSFYWoNav+V+jXobJk/LJdH+dQ1DU4qCH 52X1+uk4H9ROXucfnT58QdzEnhC8Bc0Km4d66LActif6/5IW+KOD7stZs0OUJqpQiox1Y8V X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200920_164928_977144_8D42B040 X-CRM114-Status: GOOD ( 18.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-aio , "open list:MIPS" , David Howells , Linux-MM , keyrings@vger.kernel.org, sparclinux , Christoph Hellwig , linux-arch , linux-s390 , Linux SCSI List , X86 ML , Matthew Wilcox , linux-block , Al Viro , io-uring@vger.kernel.org, linux-arm-kernel , Jens Axboe , Parisc List , Network Development , LKML , LSM List , Linux FS Devel , Andrew Morton , linuxppc-dev Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel