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 D7D13C433F5 for ; Wed, 12 Jan 2022 10:17:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 082716B0134; Wed, 12 Jan 2022 05:17:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0326C6B0135; Wed, 12 Jan 2022 05:17:57 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E63EB6B0136; Wed, 12 Jan 2022 05:17:57 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0166.hostedemail.com [216.40.44.166]) by kanga.kvack.org (Postfix) with ESMTP id D7A186B0134 for ; Wed, 12 Jan 2022 05:17:57 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 98C8590F62 for ; Wed, 12 Jan 2022 10:17:57 +0000 (UTC) X-FDA: 79021234194.07.6591A29 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf03.hostedemail.com (Postfix) with ESMTP id 1B5AC20014 for ; Wed, 12 Jan 2022 10:17:56 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id AF6DE1F3D0; Wed, 12 Jan 2022 10:17:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1641982675; 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=g/PcfchBevR47yLCk2MvJMcIoOeey+Dc7tFuclOHyHY=; b=ihOEkN8DjQyUt0ipnU90uMOZ2gXOVMRbLDzXwZb6s6F8FLHvme9bzA1Up283oRsVgW8TRI 3snyjvVlAjeBn09Iscu8aTJ2GMnUcRLx0jwB0ZIVXuvPDja9V5BdcKNwCLFIhyLOFsuMpE lL6uy541yhuj4resrieM6V346Nz/eO4= 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 71453A3B81; Wed, 12 Jan 2022 10:17:54 +0000 (UTC) Date: Wed, 12 Jan 2022 11:17:53 +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 6/9] mm: multigenerational lru: aging Message-ID: References: <20220104202227.2903605-1-yuzhao@google.com> <20220104202227.2903605-7-yuzhao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 1B5AC20014 X-Stat-Signature: yocfihn1a7obwdismi4psjoxocduxzjo Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=ihOEkN8D; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf03.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com X-HE-Tag: 1641982676-904126 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 11-01-22 18:01:29, Yu Zhao wrote: > On Mon, Jan 10, 2022 at 05:57:39PM +0100, Michal Hocko wrote: > > On Tue 04-01-22 13:22:25, Yu Zhao wrote: > > [...] > > > +static void walk_mm(struct lruvec *lruvec, struct mm_struct *mm, struct lru_gen_mm_walk *walk) > > > +{ > > > + static const struct mm_walk_ops mm_walk_ops = { > > > + .test_walk = should_skip_vma, > > > + .p4d_entry = walk_pud_range, > > > + }; > > > + > > > + int err; > > > +#ifdef CONFIG_MEMCG > > > + struct mem_cgroup *memcg = lruvec_memcg(lruvec); > > > +#endif > > > + > > > + walk->next_addr = FIRST_USER_ADDRESS; > > > + > > > + do { > > > + unsigned long start = walk->next_addr; > > > + unsigned long end = mm->highest_vm_end; > > > + > > > + err = -EBUSY; > > > + > > > + rcu_read_lock(); > > > +#ifdef CONFIG_MEMCG > > > + if (memcg && atomic_read(&memcg->moving_account)) > > > + goto contended; > > > +#endif > > > > Why do you need to check for moving_account? > > This check, if succeeds, blocks memcg migration. OK, I can see that you rely on the RCU here for the synchronization. A comment which mentions mem_cgroup_move_charge would be helpful for clarity. Is there any reason you are not using folio_memcg_lock in the pte walk instead? -- Michal Hocko SUSE Labs