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=-6.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 9726BC433DB for ; Mon, 25 Jan 2021 21:41:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A69722573 for ; Mon, 25 Jan 2021 21:41:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733052AbhAYVkz (ORCPT ); Mon, 25 Jan 2021 16:40:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:36582 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732890AbhAYVjP (ORCPT ); Mon, 25 Jan 2021 16:39:15 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A683E2083E; Mon, 25 Jan 2021 21:38:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611610714; bh=oBbSa76JFc7v8+y55SX0g1Mr9sPSRsNOv4tmWq7xrRA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ubeXULCeE5ESYXoKbbpQZvbpm7KD3rJtLMZd3bLMpG+Yf8ZlUgaes9e13MakOokA9 iEgnWl6tWG8fgiW+VJGsU1Vz4qkDtXaocuKZT5gFf6r99ZgN3QhYKOTmMnfoGOogzo zlSt15bli+VWxniwjlxtECCstKhhIQyCjc9aSnUV55QlpbsGcamdfknFZPmcXMuxob G02UJe9Qaa5X7Qu+hPXzpNUvjCDYeTaIEq+run7rkZRwSUoqDGVquo06czJpfyCKh6 lYHTox8ewX/SByv9aTWjggJVW9TsgcM9496MPOix7WOWD0WDa1bKzdlfYuPxgdGr6W 86DtTT5jWaIDg== Date: Mon, 25 Jan 2021 23:38:17 +0200 From: Mike Rapoport To: Michal Hocko 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: <20210125213817.GM6332@kernel.org> References: <20210121122723.3446-1-rppt@kernel.org> <20210121122723.3446-9-rppt@kernel.org> <20210125165451.GT827@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210125165451.GT827@dhcp22.suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org 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? > [...] > > > +static int secretmem_account_pages(struct page *page, gfp_t gfp, int order) > > +{ > > + int err; > > + > > + err = memcg_kmem_charge_page(page, gfp, order); > > + if (err) > > + return err; > > + > > + /* > > + * seceremem caches are unreclaimable kernel allocations, so treat > > + * them as unreclaimable slab memory for VM statistics purposes > > + */ > > + mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, > > + PAGE_SIZE << order); > > A lot of memcg accounted memory is not reclaimable. Why do you abuse > SLAB counter when this is not a slab owned memory? Why do you use the > kmem accounting API when __GFP_ACCOUNT should give you the same without > this details? I cannot use __GFP_ACCOUNT because cma_alloc() does not use gfp. Besides, kmem accounting with __GFP_ACCOUNT does not seem to update stats and there was an explicit request for statistics: https://lore.kernel.org/lkml/CALo0P13aq3GsONnZrksZNU9RtfhMsZXGWhK1n=xYJWQizCd4Zw@mail.gmail.com/ As for (ab)using NR_SLAB_UNRECLAIMABLE_B, as it was already discussed here: https://lore.kernel.org/lkml/20201129172625.GD557259@kernel.org/ I think that a dedicated stats counter would be too much at the moment and NR_SLAB_UNRECLAIMABLE_B is the only explicit stat for unreclaimable memory. -- Sincerely yours, Mike.