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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 B8B9FC4332B for ; Tue, 26 Jan 2021 16:39:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83E4723128 for ; Tue, 26 Jan 2021 16:39:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730624AbhAZJX3 (ORCPT ); Tue, 26 Jan 2021 04:23:29 -0500 Received: from mx2.suse.de ([195.135.220.15]:57472 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389361AbhAZJTr (ORCPT ); Tue, 26 Jan 2021 04:19:47 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611652532; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=8+K0oyxRY1+vhNkSeXzm8M4Y2R64gVVtCdOHelIF+V8=; b=kShKTVasjKcQgyk49obmmqJEv3Z3d6D+KjtCoEjGXxzkEZlE9pddLwPnfiYIY421ESnwFk s121ANy6h6Uf22zm4fCv1pqav6eTOcya5rAIE9EhMH1YsS7w7Ixp5ITIzE4PQfYNNMffQz Deb5a3d+IUk2PpGiCwbgFZJfGrBkuvI= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 36ABFB293; Tue, 26 Jan 2021 09:15:32 +0000 (UTC) Date: Tue, 26 Jan 2021 10:15:27 +0100 From: Michal Hocko To: Mike Rapoport Cc: Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , David Hildenbrand , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org, Hagen Paul Pfeifer , Palmer Dabbelt Subject: Re: [PATCH v16 08/11] secretmem: add memcg accounting Message-ID: <20210126091527.GG827@dhcp22.suse.cz> References: <20210121122723.3446-1-rppt@kernel.org> <20210121122723.3446-9-rppt@kernel.org> <20210125165451.GT827@dhcp22.suse.cz> <20210125213817.GM6332@kernel.org> <20210126073142.GY827@dhcp22.suse.cz> <20210126085654.GO6332@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210126085654.GO6332@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Tue 26-01-21 10:56:54, Mike Rapoport wrote: > On Tue, Jan 26, 2021 at 08:31:42AM +0100, Michal Hocko wrote: > > On Mon 25-01-21 23:38:17, Mike Rapoport wrote: > > > On Mon, Jan 25, 2021 at 05:54:51PM +0100, Michal Hocko wrote: > > > > On Thu 21-01-21 14:27:20, Mike Rapoport wrote: > > > > > From: Mike Rapoport > > > > > > > > > > Account memory consumed by secretmem to memcg. The accounting is updated > > > > > when the memory is actually allocated and freed. > > > > > > > > What does this mean? > > > > > > That means that the accounting is updated when secretmem does cma_alloc() > > > and cma_relase(). > > > > > > > What are the lifetime rules? > > > > > > Hmm, what do you mean by lifetime rules? > > > > OK, so let's start by reservation time (mmap time right?) then the > > instantiation time (faulting in memory). What if the calling process of > > the former has a different memcg context than the later. E.g. when you > > send your fd or inherited fd over fork will move to a different memcg. > > > > What about freeing path? E.g. when you punch a hole in the middle of > > a mapping? > > > > Please make sure to document all this. > > So, does something like this answer your question: > > --- > The memory cgroup is charged when secremem allocates pages from CMA to > increase large pages pool during ->fault() processing. OK so that is when the memory is faulted in. Good that is a standard model we have. The memcg context of the creator of the secret memory is not really important. So whoever has created is not charged. > The pages are uncharged from memory cgroup when they are released back to > CMA at the time secretme inode is evicted. > --- so effectivelly when they are unmapped, right? This is similar to anonymous memory. As I've said it would be really great to have this life cycle documented properly. > > Please note that this all is a user visible stuff that will become PITA > > (if possible) to change later on. You should really have strong > > arguments in your justification here. > > I think that adding a dedicated counter for few 2M areas per container is > not worth the churn. What kind of churn you have in mind? What is the downside? > When we'll get to the point that secretmem can be used to back the entire > guest memory we can add a new counter and it does not seem to PITA to me. What does really prevent a larger use with this implementation? -- Michal Hocko SUSE Labs