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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6E1DC433EF for ; Fri, 7 Jan 2022 09:06:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 778A56B0073; Fri, 7 Jan 2022 04:06:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 728AF6B0074; Fri, 7 Jan 2022 04:06:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5F0536B0075; Fri, 7 Jan 2022 04:06:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0183.hostedemail.com [216.40.44.183]) by kanga.kvack.org (Postfix) with ESMTP id 508096B0073 for ; Fri, 7 Jan 2022 04:06:18 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 112651809C04E for ; Fri, 7 Jan 2022 09:06:18 +0000 (UTC) X-FDA: 79002909636.26.498C7AF Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf25.hostedemail.com (Postfix) with ESMTP id B0CA4A0002 for ; Fri, 7 Jan 2022 09:06:17 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 7DF231F39C; Fri, 7 Jan 2022 09:06:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1641546376; 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=/+rkleY2pIdK7PXNX7lUi9qQ2IGYdAkkl5TG1LGhbIQ=; b=sBVGhGr6l4U+RSvPC9eGfELzbL4s1aqGpH+E88SrDgSd/jnjr3QQB2+xND6183ZRKWEMeP Zj4IiU4WZKdPGQc224yRvWu9/WIRCgHUCwF8nMPSEhluQyxZyZx4Gf01omL4jcmSiuyOIZ nvJq0a2R8LkwcGxxmHToeJFaVmCY4aE= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id BD8D9A3B8C; Fri, 7 Jan 2022 09:06:15 +0000 (UTC) Date: Fri, 7 Jan 2022 10:06:15 +0100 From: Michal Hocko To: Yu Zhao Cc: Andrew Morton , Linus Torvalds , Andi Kleen , Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Matthew Wilcox , Mel Gorman , Michael Larabel , Rik van Riel , Vlastimil Babka , Will Deacon , Ying Huang , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, page-reclaim@google.com, x86@kernel.org, Konstantin Kharlamov Subject: Re: [PATCH v6 5/9] mm: multigenerational lru: mm_struct list Message-ID: References: <20220104202227.2903605-1-yuzhao@google.com> <20220104202227.2903605-6-yuzhao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220104202227.2903605-6-yuzhao@google.com> Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=sBVGhGr6; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf25.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: B0CA4A0002 X-Stat-Signature: bra35hww4rpcz8pbc6ujhxkfckudkzcu X-HE-Tag: 1641546377-13793 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 04-01-22 13:22:24, Yu Zhao wrote: > To exploit spatial locality, the aging prefers to walk page tables to > search for young PTEs. And this patch paves the way for that. > > An mm_struct list is maintained for each memcg, and an mm_struct > follows its owner task to the new memcg when this task is migrated. How does this work actually for the memcg reclaim? I can see you lru_gen_migrate_mm on the task migration. My concern is, though, that such a task leaves all the memory behind in the previous memcg (in cgroup v2, in v1 you can opt in for charge migration). If you move the mm to a new memcg then you age it somewhere where the memory is not really consumed. -- Michal Hocko SUSE Labs