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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 AE58CC433E2 for ; Thu, 10 Sep 2020 20:37:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A4AD214F1 for ; Thu, 10 Sep 2020 20:37:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="N0o4Jr5P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727792AbgIJUhr (ORCPT ); Thu, 10 Sep 2020 16:37:47 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:60128 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726781AbgIJUbU (ORCPT ); Thu, 10 Sep 2020 16:31:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599769875; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=oG4VtYBGXuzb613fx5hBBNMTZQ49H6hy0YeFdmvTD8g=; b=N0o4Jr5PcYTMPx6n//feqv4Uglx21vVaPykquu5MNn4Dh+IzDcuxuQgiCVDjxkw2YAhZ6m zgbDPdutXNRV1OAlMnbgXmD9M5bU4FdpghIfYMDnPHScdJ3hytILcB0/Zts5NZxI4EpDgR 0F1BFFCFhKxUiE2FvzJ51d0Y+wddX6o= Received: from mail-ej1-f71.google.com (mail-ej1-f71.google.com [209.85.218.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-265-hirjGdpVMoCeQMCuV-R7GQ-1; Thu, 10 Sep 2020 16:31:12 -0400 X-MC-Unique: hirjGdpVMoCeQMCuV-R7GQ-1 Received: by mail-ej1-f71.google.com with SMTP id e13so3387861ejk.1 for ; Thu, 10 Sep 2020 13:31:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=oG4VtYBGXuzb613fx5hBBNMTZQ49H6hy0YeFdmvTD8g=; b=UbvsBQXVc9KxfjP/kXEY51rjTxuMn5ix5r+XzF9iCnJ0B8wr4+f/sKK9tZjV1YdI7F GHGkbWeZwY3UarUCOVMoMCNDBo+vgNnXwiRgtX1xetVAOvv52OB3Su+a0kxyOza97gXW wpZAAO5kxienDggm8q3NB3EpKtaboDeAAV9N1qz84HE5yLUZe0DH4TcHWzFUaVfOWd+p yJGInEHyiKPVYTuvBnIvmgz1VJiLnJqny3EvzJWWZt1h6aaxgc9sONWi53wjaXcITdWw DoNX60qBA0QrxjgjwVJcIs1OMUgCxGIMS7dopj6hi5PV3V4xjfG+rXg7/pLKGr0dUb0K P2XA== X-Gm-Message-State: AOAM533ZRPkR+hyLaMOTNdP3KEXpZYDF3nr17GWu6yZjtMJUaazTYKMK hMFkZ2iU3xMnd1D4dwsiLoKtpSFRkUZHVlsuuN+VYxe92BTzRlk6mmtX4UDyzmL9Xu/fZoySrgO KG4d7a2FM3AAXmvCM0kE9OPlo X-Received: by 2002:a17:906:4d4d:: with SMTP id b13mr10371714ejv.221.1599769871000; Thu, 10 Sep 2020 13:31:11 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwH4nFbqdIdClpGW3cyhzIHHW/NNlAPR9E4pCL3OlvSjq9ChPfVJPacAk9tIeJ6YFp4UpQGsg== X-Received: by 2002:a17:906:4d4d:: with SMTP id b13mr10371701ejv.221.1599769870830; Thu, 10 Sep 2020 13:31:10 -0700 (PDT) Received: from [192.168.3.122] (p5b0c6042.dip0.t-ipconnect.de. [91.12.96.66]) by smtp.gmail.com with ESMTPSA id d6sm21881edm.31.2020.09.10.13.31.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Sep 2020 13:31:10 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: David Hildenbrand Mime-Version: 1.0 (1.0) Subject: Re: Ways to deprecate /sys/devices/system/memory/memoryX/phys_device ? Date: Thu, 10 Sep 2020 22:31:09 +0200 Message-Id: <3E00A442-7107-48DA-8172-EED95F6E1663@redhat.com> References: Cc: David Hildenbrand , Gerald Schaefer , Michal Hocko , "akpm@linux-foundation.org" , Greg KH , =?utf-8?Q?Jan_H=C3=B6ppner?= , Heiko Carstens , "linux-mm@kvack.org" , linux-api@vger.kernel.org, Dave Hansen , "linux-kernel@vger.kernel.org" In-Reply-To: To: Dave Hansen X-Mailer: iPhone Mail (17G68) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Am 10.09.2020 um 22:01 schrieb Dave Hansen : >=20 > =EF=BB=BFOn 9/10/20 3:20 AM, David Hildenbrand wrote: >> I was just exploring how /sys/devices/system/memory/memoryX/phys_device >> is/was used. It's one of these interfaces that most probably never >> should have been added but now we are stuck with it. >=20 > While I'm all for cleanups, what specific problems is phys_device causing?= >=20 Mostly stumbling over it, understanding that it is basically unused with new= userspace for good reason, questioning its existence. E.g., I am working on virtio-mem support for s390x. Displaying misleading/wr= ong phys_device indications isn=E2=80=98t particularly helpful - especially o= nce there are different ways to hotplug memory for an architecture. > Are you hoping that we can just remove users of memoryX/* until there > are no more left, and this is the easiest place to start? At least reducing it to a minimum with clear semantics. Even with automatic o= nlining there are still reasons why we need to keep the interface for now (e= .g., reloading kexec to update the kdump headers on memory hot(un)plug). But= also standby memory handling on s399x requires it (->manual onlining).=