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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D56BEB64DA for ; Fri, 16 Jun 2023 06:40:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242161AbjFPGkd (ORCPT ); Fri, 16 Jun 2023 02:40:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241627AbjFPGka (ORCPT ); Fri, 16 Jun 2023 02:40:30 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A1C7273E for ; Thu, 15 Jun 2023 23:40:28 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 4143921EA4; Fri, 16 Jun 2023 06:40:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1686897627; h=from:from:reply-to: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=GlSD6RWNsFHyZEr4GHh8TKFlv5WJ0i1ZYa1pBLlMowc=; b=Lwaq0oM9xcU4PNbk4U2Q1L4ultP5oN78NdmmwGPF5vI82UUCor/lBmAb2uuxDQbR6Joo13 PGBl3wCAotw2hOrEqvgbKwQOFmNUBQ5Cz6Qze9QVD4WHJM5yB7c7OsK+4b1Ti//A+LaDeK Z8DdJ63vhDa82ZL+fYelXkZmQICtxzU= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 1EE2E138E8; Fri, 16 Jun 2023 06:40:27 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id lokcBdsDjGRFdAAAMHmgww (envelope-from ); Fri, 16 Jun 2023 06:40:27 +0000 Date: Fri, 16 Jun 2023 08:40:26 +0200 From: Michal Hocko To: =?utf-8?B?6LS65Lit5Z2k?= Cc: minchan@kernel.org, senozhatsky@chromium.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [External] Re: [RFC PATCH 1/3] zram: charge the compressed RAM to the page's memcgroup Message-ID: References: <20230615034830.1361853-1-hezhongkun.hzk@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 16-06-23 11:31:18, 贺中坤 wrote: > On Thu, Jun 15, 2023 at 10:21 PM Michal Hocko wrote: > > > > On Thu 15-06-23 22:13:09, 贺中坤 wrote: > > > > This is not really answering my question though. memcg under hard limit > > > > is not really my concern. This is a simpler case. I am not saying it > > > > doesn't need to get addresses but it is the memcg hard limited case that > > > > is much more interested. Because your charges are going to fail very > > > > likely and that would mean that swapout would fail AFAIU. If my > > > > understanding is wrong then it would really help to describe that case > > > > much more in the changelog. > > > > > > > > > > OK, Got it. In many cases I have tested, it will not fail because we did > > > not charge the page directly，but the objects(like slab,compressed page), > > > for the zspage may be shared by any memcg. > > > > That sounds like a broken design to me. > > -- > > Michal Hocko > > SUSE Labs > > I will try more cases in different compression ratios and make sure > that swapout will not fail. I do not think different compression methods will cut it. You essentially need some form of memory reserves - in memcg world pre-charged pool of memory readily available for the swapout. Another way would be to allow the charge to bypass the limit with a guarantee that this will be a temporal breach. -- Michal Hocko SUSE Labs