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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A5179C77B71 for ; Fri, 14 Apr 2023 17:24:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230214AbjDNRYy (ORCPT ); Fri, 14 Apr 2023 13:24:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230392AbjDNRYj (ORCPT ); Fri, 14 Apr 2023 13:24:39 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 052EAC140 for ; Fri, 14 Apr 2023 10:24:23 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id c67-20020a254e46000000b00b88f1fd158fso35280774ybb.17 for ; Fri, 14 Apr 2023 10:24:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1681493062; x=1684085062; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=1suTIWWaXvrjwoXvee3hiPz1nCSIoJ8zBj0cMHmSI7Y=; b=ikLyr+8Xr+H5vM/bYsln0btIfSDwhlyv3SopCKg3euLB29KjQafs0AtMmmr4T9EIfJ vIPC9xf1NxKqXFWckbIj0WVo4SgvKsPOQl1cOwpgB/XV40BLqns/ryvTGzxH0hPTIol7 xarcJ0GqxJFOJTIObBYAoUoAUl0iAOmFpm7/8rkUekiKozgid1NlTMyN45x5pS33IxKE d8HkpLc19gk/5O6gbpIr0ZptEhH2xIi2xu1OHofuLnINm9CQonnrWxwWMzsJ6C8Y+skF MUVvqijzMdtqQ30NGAKrF5+eZpQbbmVeMtcc7lOWf3BPP1QJqZGJHkM9DCvCxyboG1b4 logA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681493062; x=1684085062; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1suTIWWaXvrjwoXvee3hiPz1nCSIoJ8zBj0cMHmSI7Y=; b=h6dEmRuoyo3ClcugvVsVmQH4OYd1eoeT9vOsXYS8IS43CYWVfw4rHrEBZLWvH/65EO xt1vVgZm0f/xvnuxd1nLnkMaTzFRvKd+Di/EGbUNMofOl5y6vSlrlmmR8fyHBnyUJfSA S8yZrHE310YpxLgVCDMmG8h8sy8o8AzdgMpgvXT7q5YmDp3VgioFIIKrc14nDXhAIdIN 1s6UTVE3LTz28io4iPiWp+gVeqIgRfRr65sqS+7SFQa2LRGn5ko64kE7BkI+Gdd9OteW wATBuuBgTb7zS92CFO7jgi6ne6tXSFjDWgC+JU0ywmQxu6cyizPp/CVs2Etn8EAk5OXY KQHw== X-Gm-Message-State: AAQBX9doDOWQy+Sohu98/aKCitLijXp6cbyTFfKDowe56KqKxXECOSta HKvllyAKnJD2piX8NO844Wz8gcWkZho= X-Google-Smtp-Source: AKy350bMntOiUpabNyzZrQez/ekmQ/pO8bA95EPMaEz7NgDSS6qOH/7lua5qHB9B+z+FW4OM+ZLtRc32bN4= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a81:b621:0:b0:54c:bf7:1853 with SMTP id u33-20020a81b621000000b0054c0bf71853mr4241791ywh.6.1681493062225; Fri, 14 Apr 2023 10:24:22 -0700 (PDT) Date: Fri, 14 Apr 2023 17:24:20 +0000 In-Reply-To: Mime-Version: 1.0 References: Message-ID: Subject: Re: [RFC PATCH 0/6] Setting memory policy for restrictedmem file From: Sean Christopherson To: Michal Hocko Cc: Ackerley Tng , kvm@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org, aarcange@redhat.com, ak@linux.intel.com, akpm@linux-foundation.org, arnd@arndb.de, bfields@fieldses.org, bp@alien8.de, chao.p.peng@linux.intel.com, corbet@lwn.net, dave.hansen@intel.com, david@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, hpa@zytor.com, hughd@google.com, jlayton@kernel.org, jmattson@google.com, joro@8bytes.org, jun.nakajima@intel.com, kirill.shutemov@linux.intel.com, linmiaohe@huawei.com, luto@kernel.org, mail@maciej.szmigiero.name, michael.roth@amd.com, mingo@redhat.com, naoya.horiguchi@nec.com, pbonzini@redhat.com, qperret@google.com, rppt@kernel.org, shuah@kernel.org, steven.price@arm.com, tabba@google.com, tglx@linutronix.de, vannapurve@google.com, vbabka@suse.cz, vkuznets@redhat.com, wanpengli@tencent.com, wei.w.wang@intel.com, x86@kernel.org, yu.c.zhang@linux.intel.com, muchun.song@linux.dev, feng.tang@intel.com, brgerst@gmail.com, rdunlap@infradead.org, masahiroy@kernel.org, mailhol.vincent@wanadoo.fr Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Apr 14, 2023, Michal Hocko wrote: > On Fri 14-04-23 00:11:49, Ackerley Tng wrote: > > 3. A more generic fbind(): it seems like this new functionality is > > really only needed for restrictedmem files, hence a separate, > > specific syscall was proposed to avoid complexities with handling > > conflicting policies that may be specified via other syscalls like > > mbind() > > I do not think it is a good idea to make the syscall restrict mem > specific. +1. IMO, any uAPI that isn't directly related to the fundamental properties of restricted memory, i.e. isn't truly unique to restrictedmem, should be added as generic fd-based uAPI. > History shows that users are much more creative when it comes > to usecases than us. I do understand that the nature of restricted > memory is that it is not mapable but memory policies without a mapping > are a reasonable concept in genereal. After all this just tells where > the memory should be allocated from. Do we need to implement that for > any other fs? No, you can safely return EINVAL for anything but > memfd_restricted fd for now but you shouldn't limit usecases upfront. I would even go a step further and say that we should seriously reconsider the design/implemenation of memfd_restricted() if a generic fbind() needs explicit handling from the restricted memory code. One of the goals with memfd_restricted() is to rely on the underlying backing store to handle all of the "normal" behaviors.