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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 708A9C31E40 for ; Mon, 12 Aug 2019 14:56:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F38642085A for ; Mon, 12 Aug 2019 14:56:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="NQ/9B5p6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F38642085A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5A5956B0003; Mon, 12 Aug 2019 10:56:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 52F126B0005; Mon, 12 Aug 2019 10:56:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3CF996B0006; Mon, 12 Aug 2019 10:56:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0210.hostedemail.com [216.40.44.210]) by kanga.kvack.org (Postfix) with ESMTP id 13FB46B0003 for ; Mon, 12 Aug 2019 10:56:30 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id A9E81180AD7C3 for ; Mon, 12 Aug 2019 14:56:29 +0000 (UTC) X-FDA: 75814076898.08.mint42_72d36f83da159 X-HE-Tag: mint42_72d36f83da159 X-Filterd-Recvd-Size: 7366 Received: from mail-pg1-f196.google.com (mail-pg1-f196.google.com [209.85.215.196]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Mon, 12 Aug 2019 14:56:28 +0000 (UTC) Received: by mail-pg1-f196.google.com with SMTP id r26so13665025pgl.10 for ; Mon, 12 Aug 2019 07:56:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=3NQFlI4lPYDkvZgs+SnZFXq303TlZRy3bgOdazYblNc=; b=NQ/9B5p6EJnc/jGagbLM/8utrsVRGSqpApLAwGccX5pyS3J/WcnaL76DY5ZPmNj/me +sOQkXutAriyMqi+oLObLZvGQLAia8jcHXEZ76S2/2iX/m6q9ZxUBAuq6hc8fExbhUE5 WykTmRJksJRkfuwSeyqAdKimKYBeiv/vOihXA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=3NQFlI4lPYDkvZgs+SnZFXq303TlZRy3bgOdazYblNc=; b=j+iEvJtvWoRQ9ITuTfMgrRmsR76McvRgqYqsbCSusXFmjAbj43PMRHnS5mVwPnHlS9 45Qu+4e/SvZzf41N9K6gp6tN23EjCKsmgAFdXRwnswi6oC55NCIz2l/0Zx9I3zGA9JM4 2LnbvMplTrTWZRmVdhtquQJG8RA/ov86DdXYTXuFhOiLwp/0EeWCH//1aR7JHTBjWRYJ il4mIMQLkedvq84okuxkq/pUBfAkyyLjPJ3YDEOTqlaV1kVEHLMffiDgkMOj2VoS82ME CVLyJezFmXE/ZSiY8fCDSqgbc2noqZKR/M1th79QHWKVoDSBS3RhPKwKRRXgRZkq7IeD Ls3A== X-Gm-Message-State: APjAAAWZFkbv/WcLoLyGQaB/o2ipQAxr0sp1QoofJ4IL7hfK8LnEjRxP Nwuy9+E8/AgQJ9grxK7nLyJuKg== X-Google-Smtp-Source: APXvYqwENYmtyILjOnl4HilVvOmaVrKuBkJ28bAMVAwHSpsNFJRH+v3wmBUJf3pYNep/OXJa+KX7pQ== X-Received: by 2002:a65:4786:: with SMTP id e6mr29905703pgs.448.1565621782717; Mon, 12 Aug 2019 07:56:22 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id y23sm5052754pfr.86.2019.08.12.07.56.21 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 12 Aug 2019 07:56:21 -0700 (PDT) Date: Mon, 12 Aug 2019 10:56:20 -0400 From: Joel Fernandes To: Michal Hocko Cc: Andrew Morton , linux-kernel@vger.kernel.org, Alexey Dobriyan , Borislav Petkov , Brendan Gregg , Catalin Marinas , Christian Hansen , dancol@google.com, fmayer@google.com, "H. Peter Anvin" , Ingo Molnar , Jonathan Corbet , Kees Cook , kernel-team@android.com, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Mike Rapoport , minchan@kernel.org, namhyung@google.com, paulmck@linux.ibm.com, Robin Murphy , Roman Gushchin , Stephen Rothwell , surenb@google.com, Thomas Gleixner , tkjos@google.com, Vladimir Davydov , Vlastimil Babka , Will Deacon Subject: Re: [PATCH v5 1/6] mm/page_idle: Add per-pid idle page tracking using virtual index Message-ID: <20190812145620.GB224541@google.com> References: <20190807171559.182301-1-joel@joelfernandes.org> <20190807130402.49c9ea8bf144d2f83bfeb353@linux-foundation.org> <20190807204530.GB90900@google.com> <20190807135840.92b852e980a9593fe91fbf59@linux-foundation.org> <20190807213105.GA14622@google.com> <20190808080044.GA18351@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190808080044.GA18351@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 Thu, Aug 08, 2019 at 10:00:44AM +0200, Michal Hocko wrote: > On Wed 07-08-19 17:31:05, Joel Fernandes wrote: > > On Wed, Aug 07, 2019 at 01:58:40PM -0700, Andrew Morton wrote: > > > On Wed, 7 Aug 2019 16:45:30 -0400 Joel Fernandes wrote: > > > > > > > On Wed, Aug 07, 2019 at 01:04:02PM -0700, Andrew Morton wrote: > > > > > On Wed, 7 Aug 2019 13:15:54 -0400 "Joel Fernandes (Google)" wrote: > > > > > > > > > > > In Android, we are using this for the heap profiler (heapprofd) which > > > > > > profiles and pin points code paths which allocates and leaves memory > > > > > > idle for long periods of time. This method solves the security issue > > > > > > with userspace learning the PFN, and while at it is also shown to yield > > > > > > better results than the pagemap lookup, the theory being that the window > > > > > > where the address space can change is reduced by eliminating the > > > > > > intermediate pagemap look up stage. In virtual address indexing, the > > > > > > process's mmap_sem is held for the duration of the access. > > > > > > > > > > So is heapprofd a developer-only thing? Is heapprofd included in > > > > > end-user android loads? If not then, again, wouldn't it be better to > > > > > make the feature Kconfigurable so that Android developers can enable it > > > > > during development then disable it for production kernels? > > > > > > > > Almost all of this code is already configurable with > > > > CONFIG_IDLE_PAGE_TRACKING. If you disable it, then all of this code gets > > > > disabled. > > > > > > > > Or are you referring to something else that needs to be made configurable? > > > > > > Yes - the 300+ lines of code which this patchset adds! > > > > > > The impacted people will be those who use the existing > > > idle-page-tracking feature but who will not use the new feature. I > > > guess we can assume this set is small... > > > > Yes, I think this set should be small. The code size increase of page_idle.o > > is from ~1KB to ~2KB. Most of the extra space is consumed by > > page_idle_proc_generic() function which this patch adds. I don't think adding > > another CONFIG option to disable this while keeping existing > > CONFIG_IDLE_PAGE_TRACKING enabled, is worthwhile but I am open to the > > addition of such an option if anyone feels strongly about it. I believe that > > once this patch is merged, most like this new interface being added is what > > will be used more than the old interface (for some of the usecases) so it > > makes sense to keep it alive with CONFIG_IDLE_PAGE_TRACKING. > > I would tend to agree with Joel here. The functionality falls into an > existing IDLE_PAGE_TRACKING config option quite nicely. If there really > are users who want to save some space and this is standing in the way > then they can easily add a new config option with some justification so > the savings are clear. Without that an additional config simply adds to > the already existing configurability complexity and balkanization. Michal, Andrew, Minchan, Would you have any other review comments on the v5 series? This is just a new interface that does not disrupt existing users of the older page-idle tracking, so as such it is a safe change (as in, doesn't change existing functionality except for the draining bug fix). thanks, - Joel