Received: by 2002:a25:b794:0:0:0:0:0 with SMTP id n20csp2769036ybh; Mon, 5 Aug 2019 06:33:26 -0700 (PDT) X-Google-Smtp-Source: APXvYqxMLPqwNE//67JzO/xAopskWu70iC1/BD/yKEEJPtPMx8Y0LmmtsJItxE3z4AZsP0amJbdI X-Received: by 2002:a63:121b:: with SMTP id h27mr121351067pgl.335.1565012006602; Mon, 05 Aug 2019 06:33:26 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1565012006; cv=none; d=google.com; s=arc-20160816; b=sdKGlcxT8c4KgeC+pAtnSB0gcRsv24JINIEVC7b2g4pmjf/oawbIY8djcF+ofG9VqP 0ZfTjbbi10jrq9AiwP3fJo4SWdYRwZGaxhnWdnPTfyfzLs03Qwp78iJe0uOFJsuIy/Ft jgjklZhTXp6IKPjluvO4ewyj8BsZfuHoMTz26P74jqNKK1G0TCOdlD9+s3JTtU4wEK+4 8KwhASgjFUMEdFuESDzpxo+plMPHjylMicEljSm7oBE+VNxnODBzRkkf9DJx+3y+CqIU dfW8wmoyNnmRZ9U5XnxMUGkwgkL88M1sGpwPIdXc7Spd+Y8rJC6O92D5HCtgfaKeW6uP mTuw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-disposition:mime-version:references:message-id:subject:cc :to:from:date; bh=ShBgVtpwp30olNzWLd8zAsYWuUGiRG22aEjjNI7xOCY=; b=Pv39KDsrUt78IWwtztcUeS2sIpgH11gJML9jKjtBLvKcZTDtNASlMVcwkqHYjb0aiE wNVla4s3VYW/YV7gzxi0hYP8k6rlzvr1ZbSVUymB53ceoR5twr2NO/TRqVibI1wwKW4U 3E6Qgjr6aXN/7nkjwkWQTUXLZhOGSIFs5Xlt1ly1xt5YLAyiX9oReYPmdcef20zsC0rk NI3rEKsNMWK+QFgYKPcymHQ9bqZMY2pwmPLWWBt86cOp04XbNST2O7vhDz7QmdH7RzNZ oic3fIcFCPUtFg6fj2/4JWScaIHL1cQEDh3NhdNcxzxiqHBZRUnnomul6wkqiYq/Hy2W YDDQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id n1si13398690pjo.28.2019.08.05.06.33.10; Mon, 05 Aug 2019 06:33:26 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730147AbfHENbX (ORCPT + 99 others); Mon, 5 Aug 2019 09:31:23 -0400 Received: from mx2.suse.de ([195.135.220.15]:49548 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729755AbfHENbW (ORCPT ); Mon, 5 Aug 2019 09:31:22 -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 AEAF1ACB4; Mon, 5 Aug 2019 13:31:20 +0000 (UTC) Date: Mon, 5 Aug 2019 15:31:19 +0200 From: Michal Hocko To: Vlastimil Babka Cc: "Artem S. Tashkinov" , linux-kernel@vger.kernel.org, linux-mm , Johannes Weiner , Suren Baghdasaryan Subject: Re: Let's talk about the elephant in the room - the Linux kernel's inability to gracefully handle low memory pressure Message-ID: <20190805133119.GO7597@dhcp22.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Mon 05-08-19 14:13:16, Vlastimil Babka wrote: > On 8/4/19 11:23 AM, Artem S. Tashkinov wrote: > > Hello, > > > > There's this bug which has been bugging many people for many years > > already and which is reproducible in less than a few minutes under the > > latest and greatest kernel, 5.2.6. All the kernel parameters are set to > > defaults. > > > > Steps to reproduce: > > > > 1) Boot with mem=4G > > 2) Disable swap to make everything faster (sudo swapoff -a) > > 3) Launch a web browser, e.g. Chrome/Chromium or/and Firefox > > 4) Start opening tabs in either of them and watch your free RAM decrease > > > > Once you hit a situation when opening a new tab requires more RAM than > > is currently available, the system will stall hard. You will barely be > > able to move the mouse pointer. Your disk LED will be flashing > > incessantly (I'm not entirely sure why). You will not be able to run new > > applications or close currently running ones. > > > This little crisis may continue for minutes or even longer. I think > > that's not how the system should behave in this situation. I believe > > something must be done about that to avoid this stall. > > Yeah that's a known problem, made worse SSD's in fact, as they are able > to keep refaulting the last remaining file pages fast enough, so there > is still apparent progress in reclaim and OOM doesn't kick in. > > At this point, the likely solution will be probably based on pressure > stall monitoring (PSI). I don't know how far we are from a built-in > monitor with reasonable defaults for a desktop workload, so CCing > relevant folks. Another potential approach would be to consider the refault information we have already for file backed pages. Once we start reclaiming only workingset pages then we should be trashing, right? It cannot be as precise as the cost model which can be defined around PSI but it might give us at least a fallback measure. This is a really just an idea for a primitive detection. Most likely incorrect one but it shows an idea at least. It is completely untested and might be completely broken so unless somebody is really brave and doesn't run anything that would be missed then I do not recommend to run it. diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 70394cabaf4e..7f30c78b4fbc 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -300,6 +300,7 @@ struct lruvec { atomic_long_t inactive_age; /* Refaults at the time of last reclaim cycle */ unsigned long refaults; + atomic_t workingset_refaults; #ifdef CONFIG_MEMCG struct pglist_data *pgdat; #endif diff --git a/include/linux/swap.h b/include/linux/swap.h index 4bfb5c4ac108..4401753c3912 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -311,6 +311,15 @@ void *workingset_eviction(struct page *page); void workingset_refault(struct page *page, void *shadow); void workingset_activation(struct page *page); +bool lruvec_trashing(struct lruvec *lruvec) +{ + /* + * One quarter of the inactive list is constantly refaulting. + * This suggests that we are trashing. + */ + return 4 * atomic_read(&lruvec->workingset_refaults) > lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES); +} + /* Only track the nodes of mappings with shadow entries */ void workingset_update_node(struct xa_node *node); #define mapping_set_update(xas, mapping) do { \ diff --git a/mm/vmscan.c b/mm/vmscan.c index 7889f583ced9..d198594af0cd 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2381,6 +2381,11 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, denominator); break; case SCAN_FILE: + if (lruvec_trashing(lruvec)) { + size = 0; + scan = 0; + break; + } case SCAN_ANON: /* Scan one type exclusively */ if ((scan_balance == SCAN_FILE) != file) { diff --git a/mm/workingset.c b/mm/workingset.c index e0b4edcb88c8..ee4c45b27e34 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -309,17 +309,25 @@ void workingset_refault(struct page *page, void *shadow) * don't act on pages that couldn't stay resident even if all * the memory was available to the page cache. */ - if (refault_distance > active_file) + if (refault_distance > active_file) { + atomic_set(&lruvec->workingset_refaults, 0); goto out; + } SetPageActive(page); atomic_long_inc(&lruvec->inactive_age); inc_lruvec_state(lruvec, WORKINGSET_ACTIVATE); + atomic_inc(&lruvec->workingset_refaults); /* Page was active prior to eviction */ if (workingset) { SetPageWorkingset(page); inc_lruvec_state(lruvec, WORKINGSET_RESTORE); + /* + * Double the trashing numbers for the actual working set. + * refaults + */ + atomic_inc(&lruvec->workingset_refaults); } out: rcu_read_unlock(); -- Michal Hocko SUSE Labs