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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 108F0C32789 for ; Fri, 2 Nov 2018 17:48:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C26052081B for ; Fri, 2 Nov 2018 17:48:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C26052081B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728060AbeKCC4Y (ORCPT ); Fri, 2 Nov 2018 22:56:24 -0400 Received: from mx2.suse.de ([195.135.220.15]:38510 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726700AbeKCC4Y (ORCPT ); Fri, 2 Nov 2018 22:56:24 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0669AAF77; Fri, 2 Nov 2018 17:48:23 +0000 (UTC) Date: Fri, 2 Nov 2018 18:48:23 +0100 From: Michal Hocko To: Roman Gushchin Cc: Dexuan Cui , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Kernel Team , Shakeel Butt , Johannes Weiner , Tejun Heo , Rik van Riel , Konstantin Khlebnikov , Matthew Wilcox , "Stable@vger.kernel.org" Subject: Re: Will the recent memory leak fixes be backported to longterm kernels? Message-ID: <20181102174823.GI28039@dhcp22.suse.cz> References: <20181102005816.GA10297@tower.DHCP.thefacebook.com> <20181102073009.GP23921@dhcp22.suse.cz> <20181102154844.GA17619@tower.DHCP.thefacebook.com> <20181102161314.GF28039@dhcp22.suse.cz> <20181102162237.GB17619@tower.DHCP.thefacebook.com> <20181102165147.GG28039@dhcp22.suse.cz> <20181102172547.GA19042@tower.DHCP.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181102172547.GA19042@tower.DHCP.thefacebook.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 02-11-18 17:25:58, Roman Gushchin wrote: > On Fri, Nov 02, 2018 at 05:51:47PM +0100, Michal Hocko wrote: > > On Fri 02-11-18 16:22:41, Roman Gushchin wrote: [...] > > > 2) We do forget to scan the last page in the LRU list. So if we ended up with > > > 1-page long LRU, it can stay there basically forever. > > > > Why > > /* > > * If the cgroup's already been deleted, make sure to > > * scrape out the remaining cache. > > */ > > if (!scan && !mem_cgroup_online(memcg)) > > scan = min(size, SWAP_CLUSTER_MAX); > > > > in get_scan_count doesn't work for that case? > > No, it doesn't. Let's look at the whole picture: > > size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); > scan = size >> sc->priority; > /* > * If the cgroup's already been deleted, make sure to > * scrape out the remaining cache. > */ > if (!scan && !mem_cgroup_online(memcg)) > scan = min(size, SWAP_CLUSTER_MAX); > > If size == 1, scan == 0 => scan = min(1, 32) == 1. > And after proportional adjustment we'll have 0. My friday brain hurst when looking at this but if it doesn't work as advertized then it should be fixed. I do not see any of your patches to touch this logic so how come it would work after them applied? -- Michal Hocko SUSE Labs