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 84083C433E2 for ; Thu, 10 Sep 2020 20:41:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27C0120829 for ; Thu, 10 Sep 2020 20:41:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C9bZqdKb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726419AbgIJUhe (ORCPT ); Thu, 10 Sep 2020 16:37:34 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:36678 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726855AbgIJUbU (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=1599769874; 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=C9bZqdKbaeDJakDOqUDQblf0NOkQfYT97zSVih1hf2bO/l8pkg8iFkHRyRxrBG/fFCdvNT uT5eVNfD4jOZ+4EmKn3CxzEnkxC5L2qCs0utjj/vPfvaF7FE0JyWVtov3mcGzLEYr8Mfsm EuCSFdRE91WUyv/bVidX6Dv1iOF4JG0= Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-267-FHMnbu0QNo-jRi-DLf9ZHA-1; Thu, 10 Sep 2020 16:31:12 -0400 X-MC-Unique: FHMnbu0QNo-jRi-DLf9ZHA-1 Received: by mail-ed1-f71.google.com with SMTP id d13so3053909edz.18 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=JSSrptN43R1QAl/BWbZtP2JQUINhlFwudUT9Nc/fjJKghF6A5LVEWH7v6ewkMtUaqN fzI5eOQiP+qewv8bjhyACdoyqpKwgNpUhwDkpSvy3PnfwdITv1Zo+HxSZHS1Lv0L1nWm zbkljhen+f5V4xmmpqD844eIgW9tM/O0atQTjrma38UTyIORiEW7R7Nxw8WyGJFLAV89 6pg/UxRvW67rcmcEFN6OYrfKKvjhwE10AX9FsA47uMCA7JzGtV9aDeiScjyFprsm2GrO eCdYLOid/e5koHadFcAAPPouXIPzDpGEoPPW/5Z61mNGhNNru0Y4b0qdN7AOeq4qqlGK 59QQ== X-Gm-Message-State: AOAM533O9Fljdpb9iihbLKQ2fk0l8FK2gJNE0Bj5s2LaqnphMLpTkptX H/kc7HTosDBfk2CjZKb7KiVi038GfoxuyfN+xuDLDkoqdFUsge7ynYQe53iE9bsPaTx/qy49tPo mZvjQDjwkzOAOsumYMHGz X-Received: by 2002:a17:906:4d4d:: with SMTP id b13mr10371708ejv.221.1599769870992; Thu, 10 Sep 2020 13:31:10 -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-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@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).=