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=1.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, FSL_HELO_FAKE,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT 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 F2356C072B1 for ; Tue, 28 May 2019 11:44:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A94322133F for ; Tue, 28 May 2019 11:44:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OXrfO0e3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A94322133F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5A4A06B026E; Tue, 28 May 2019 07:44:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 554966B026F; Tue, 28 May 2019 07:44:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4446B6B0272; Tue, 28 May 2019 07:44:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pf1-f198.google.com (mail-pf1-f198.google.com [209.85.210.198]) by kanga.kvack.org (Postfix) with ESMTP id 0D8DF6B026E for ; Tue, 28 May 2019 07:44:44 -0400 (EDT) Received: by mail-pf1-f198.google.com with SMTP id d125so12398618pfd.3 for ; Tue, 28 May 2019 04:44:44 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:sender:date:from:to:cc:subject :message-id:references:mime-version:content-disposition:in-reply-to :user-agent; bh=Na+J22i77Z4lW2CgfdPS10rXWxVdK/zIAtW3TAGkfc0=; b=Ys2cJrO88v6bdf0PIZJazya9rbB3cHXrY46J0fNe3hKAes20XpKuPNP0vzqfKF8DPT 8R3hw125pqXsKD5U4HVcBUJQOGkAQGyQylBT15704q19CTQhcyc6tMuS1V9Pk6DLiRh6 4Wo1qnidVlctFjZxraXtNartvLcaB5VDx5JqSFIrPLfinuA5c7nFkayTpCSl4B+KrDjZ VZSoED/SqMXqIuNJSKNf8lBtA0gfJYEMsS7j1zR0hjLA6Y+gU8mxSzmxcwJZo49/7cCy kYeia23GnsuyPswBVfmQ2KtW6FbKMOqlOQKQY0YV737PSGrV6eYG36lqRXNeRs2W9aBB GkVg== X-Gm-Message-State: APjAAAXRumdz9Om6T9vtVu7NKQZIUv1ZWEXZfbA5jkf11UiScbdu+6fT VyEhhu6ZZhrNjawKr3SgcwnXAqQ511eMGZwU03Y5XYLGn1LISNjV8jPkwTnjmZYA/bhgAk22Aza zTSm0zfcL3QM597ZSHfWg8Za7wh3tDZ+ZKjbOkHR30CuLmTT22ttualOkMUaQ1ro= X-Received: by 2002:a17:902:112c:: with SMTP id d41mr19185719pla.33.1559043883687; Tue, 28 May 2019 04:44:43 -0700 (PDT) X-Received: by 2002:a17:902:112c:: with SMTP id d41mr19185660pla.33.1559043882980; Tue, 28 May 2019 04:44:42 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1559043882; cv=none; d=google.com; s=arc-20160816; b=q1YCFGzrw6x0sevO2Q0zbvwCA+Bp5unwv74DmASRF824Rgxsr0QX4ap7DEcRC7NcUH AfmGlBynjxcX0KN3fe7OPxnrHNgQAP6rceMbvaUHzGtwGBSFZaZYavE4PGfL2sTep4Wx iqs70BMIisaxa9oJ6YhLl5lVV/0yzzNLzeee/Vl9G3AuuEsB+abOp6k/HLB1/K8FGeYE Zf1YSqIMPeZvPf/pCII2xbiGB1IDcovANuyb1Vfk/K0Q1eYPZCbc15n5HxME/mQuWdS0 8PKBeEmQvJivTL05DI9ZMUgDrxuUVzRzGammkB65cjEoBnOtCtszwVHtXskTDBz8VyJF N6uA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:sender:dkim-signature; bh=Na+J22i77Z4lW2CgfdPS10rXWxVdK/zIAtW3TAGkfc0=; b=CWt2LGBRgxn95uqlci4vLrupW6NXPpaBweVjJ3Rk0U0JcF98i1TaIZIVFtooF44L2X ipJX5ouqoEFFsrkj0VhgnTlGDd1M1ldfD1qB6l/iwXbR1qBb5murSFRSZhTu3AX5zmye ANKi9CwN5Zjs1gbqDsiPuy2NsHP+1nAShhCPJ3qoV1IUrLPYYKMk39i/7q6l/XOLRUeQ L0jUKZG4zxruF9x7i7GP2PEuIw3F2nMl0t+XQZsfjWAnOaYfQwj5PVqtQ1TgsHHLIphE hb9mm+mY6ZAauzlXZ2OR7U7rRNBfZunGfSaPrtLvGKWQSipwx9uRh+ee+3dzPe8YPTkJ pElA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=OXrfO0e3; spf=pass (google.com: domain of minchan.kim@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id a21sor3265495pgh.0.2019.05.28.04.44.42 for (Google Transport Security); Tue, 28 May 2019 04:44:42 -0700 (PDT) Received-SPF: pass (google.com: domain of minchan.kim@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=OXrfO0e3; spf=pass (google.com: domain of minchan.kim@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Na+J22i77Z4lW2CgfdPS10rXWxVdK/zIAtW3TAGkfc0=; b=OXrfO0e3RlFaNQy3MzONif4phiuHMCrfpnn6bbGelKBttsjDb7M44ZI+FJjgbUxw6f 7vXbGVdyuku1hUT89ULnYttsb2u5kz+/BF/U8tcBofrdT60RhDF7fwu4ghS6H7ZfsAJa FZ50GaZ9uRRD7wN2LYuLslXoDyELhO8unuwv8Xwg3UAse7oMSN4FPEALNexObmpuMFW/ 5tA/FWmvQH7GohrjdijN5eSt6qT+A7WGKgpjeoFVUudB1fizEiT481PdyYQ3Z5oxZlmg byTjYxHrYSLJKGsm3NO5UVkJkblMmBrgaHfU+8U+83lHzKF6n4q9it0LigqhyMDCjINY getA== X-Google-Smtp-Source: APXvYqxKdDbXQTCQ2wTlaKWGq9gz76gsK2o3fQBBvCu+KCLAp37410V79lyMGOqtSpKnkp3QPk1hFQ== X-Received: by 2002:a65:5206:: with SMTP id o6mr1937077pgp.248.1559043882565; Tue, 28 May 2019 04:44:42 -0700 (PDT) Received: from google.com ([2401:fa00:d:0:98f1:8b3d:1f37:3e8]) by smtp.gmail.com with ESMTPSA id v4sm8549594pfe.180.2019.05.28.04.44.38 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 28 May 2019 04:44:41 -0700 (PDT) Date: Tue, 28 May 2019 20:44:36 +0900 From: Minchan Kim To: Michal Hocko Cc: Daniel Colascione , Andrew Morton , LKML , linux-mm , Johannes Weiner , Tim Murray , Joel Fernandes , Suren Baghdasaryan , Shakeel Butt , Sonny Rao , Brian Geffon , Linux API Subject: Re: [RFC 7/7] mm: madvise support MADV_ANONYMOUS_FILTER and MADV_FILE_FILTER Message-ID: <20190528114436.GB30365@google.com> References: <20190528032632.GF6879@google.com> <20190528062947.GL1658@dhcp22.suse.cz> <20190528081351.GA159710@google.com> <20190528084927.GB159710@google.com> <20190528090821.GU1658@dhcp22.suse.cz> <20190528103256.GA9199@google.com> <20190528104117.GW1658@dhcp22.suse.cz> <20190528111208.GA30365@google.com> <20190528112840.GY1658@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190528112840.GY1658@dhcp22.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Tue, May 28, 2019 at 01:28:40PM +0200, Michal Hocko wrote: > On Tue 28-05-19 20:12:08, Minchan Kim wrote: > > On Tue, May 28, 2019 at 12:41:17PM +0200, Michal Hocko wrote: > > > On Tue 28-05-19 19:32:56, Minchan Kim wrote: > > > > On Tue, May 28, 2019 at 11:08:21AM +0200, Michal Hocko wrote: > > > > > On Tue 28-05-19 17:49:27, Minchan Kim wrote: > > > > > > On Tue, May 28, 2019 at 01:31:13AM -0700, Daniel Colascione wrote: > > > > > > > On Tue, May 28, 2019 at 1:14 AM Minchan Kim wrote: > > > > > > > > if we went with the per vma fd approach then you would get this > > > > > > > > > feature automatically because map_files would refer to file backed > > > > > > > > > mappings while map_anon could refer only to anonymous mappings. > > > > > > > > > > > > > > > > The reason to add such filter option is to avoid the parsing overhead > > > > > > > > so map_anon wouldn't be helpful. > > > > > > > > > > > > > > Without chiming on whether the filter option is a good idea, I'd like > > > > > > > to suggest that providing an efficient binary interfaces for pulling > > > > > > > memory map information out of processes. Some single-system-call > > > > > > > method for retrieving a binary snapshot of a process's address space > > > > > > > complete with attributes (selectable, like statx?) for each VMA would > > > > > > > reduce complexity and increase performance in a variety of areas, > > > > > > > e.g., Android memory map debugging commands. > > > > > > > > > > > > I agree it's the best we can get *generally*. > > > > > > Michal, any opinion? > > > > > > > > > > I am not really sure this is directly related. I think the primary > > > > > question that we have to sort out first is whether we want to have > > > > > the remote madvise call process or vma fd based. This is an important > > > > > distinction wrt. usability. I have only seen pid vs. pidfd discussions > > > > > so far unfortunately. > > > > > > > > With current usecase, it's per-process API with distinguishable anon/file > > > > but thought it could be easily extended later for each address range > > > > operation as userspace getting smarter with more information. > > > > > > Never design user API based on a single usecase, please. The "easily > > > extended" part is by far not clear to me TBH. As I've already mentioned > > > several times, the synchronization model has to be thought through > > > carefuly before a remote process address range operation can be > > > implemented. > > > > I agree with you that we shouldn't design API on single usecase but what > > you are concerning is actually not our usecase because we are resilient > > with the race since MADV_COLD|PAGEOUT is not destruptive. > > Actually, many hints are already racy in that the upcoming pattern would > > be different with the behavior you thought at the moment. > > How come they are racy wrt address ranges? You would have to be in > multithreaded environment and then the onus of synchronization is on > threads. That model is quite clear. But we are talking about separate Think about MADV_FREE. Allocator would think the chunk is worth to mark "freeable" but soon, user of the allocator asked the chunk - ie, it's not freeable any longer once user start to use it. My point is that kinds of *hints* are always racy so any synchronization couldn't help a lot. That's why I want to restrict hints process_madvise supports as such kinds of non-destruptive one at next respin. > processes and some of them might be even not aware of an external entity > tweaking their address space. > > > If you are still concerning of address range synchronization, how about > > moving such hints to per-process level like prctl? > > Does it make sense to you? > > No it doesn't. How is prctl any relevant to any address range > operations. "whether we want to have the remote madvise call process or vma fd based." You asked the above question and I answered we are using process level hints but anon/vma filter at this moment. That's why I told you prctl to make forward progress on discussion.