From patchwork Wed Jun 3 22:58:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11586407 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6A3DF138C for ; Wed, 3 Jun 2020 22:58:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3787920B80 for ; Wed, 3 Jun 2020 22:58:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1bzRyIRm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3787920B80 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2223B28002C; Wed, 3 Jun 2020 18:58:54 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 1D26C280003; Wed, 3 Jun 2020 18:58:54 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0E8BF28002C; Wed, 3 Jun 2020 18:58:54 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0066.hostedemail.com [216.40.44.66]) by kanga.kvack.org (Postfix) with ESMTP id E994E280003 for ; Wed, 3 Jun 2020 18:58:53 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id BBC1C181AEF09 for ; Wed, 3 Jun 2020 22:58:53 +0000 (UTC) X-FDA: 76889417346.05.bears91_136a58725f408 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id AB2C61817BE41 for ; Wed, 3 Jun 2020 22:58:53 +0000 (UTC) X-Spam-Summary: 2,0,0,2ad9cf25eead82e8,d41d8cd98f00b204,akpm@linux-foundation.org,,RULES_HIT:41:355:379:800:960:966:967:973:988:989:1260:1263:1345:1359:1381:1431:1437:1534:1542:1711:1730:1747:1777:1792:2196:2199:2393:2525:2553:2559:2563:2682:2685:2693:2859:2897:2898:2902:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3353:3865:3867:3868:3870:3871:3872:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4321:4385:4605:5007:6119:6261:6653:7576:7903:8599:9025:9121:9545:10004:10913:11026:11658:11914:12043:12048:12297:12438:12517:12519:12555:12679:12783:12986:13255:13846:14181:14721:14849:21063:21080:21451:21627:21939:30054:30070:30090,0,RBL:198.145.29.99:@linux-foundation.org:.lbl8.mailshell.net-62.2.0.100 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:23,LUA_SUMMARY:none X-HE-Tag: bears91_136a58725f408 X-Filterd-Recvd-Size: 3523 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Wed, 3 Jun 2020 22:58:53 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 78EF920FC3; Wed, 3 Jun 2020 22:58:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591225132; bh=E3syZkaP08qO3eFWi5LPV4vQuinVw2/CguCnQZLywXY=; h=Date:From:To:Subject:In-Reply-To:From; b=1bzRyIRm6oGeuiSX9N1arS0RtfArwsihJ+vvbdIdrvzolNoPLmVsyKjOU7LFjxQMr SxHqK5xU6nIpOrC+pWOzwsAR+eNxwO8bpmcxfB7/BReQg9r4Q4xOaGzQpSV6toYwcy 52mF5pZPZF68cNOqtqCYrKXbK50GToh4QqEfaGcw= Date: Wed, 03 Jun 2020 15:58:52 -0700 From: Andrew Morton To: akpm@linux-foundation.org, bhe@redhat.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 040/131] mm/page_alloc.c: clear out zone->lowmem_reserve[] if the zone is empty Message-ID: <20200603225852.6Gh1tflS0%akpm@linux-foundation.org> In-Reply-To: <20200603155549.e041363450869eaae4c7f05b@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: AB2C61817BE41 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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: From: Baoquan He Subject: mm/page_alloc.c: clear out zone->lowmem_reserve[] if the zone is empty When requesting memory allocation from a specific zone is not satisfied, it will fall to lower zone to try allocating memory. In this case, lower zone's ->lowmem_reserve[] will help protect its own memory resource. The higher the relevant ->lowmem_reserve[] is, the harder the upper zone can get memory from this lower zone. However, this protection mechanism should be applied to populated zone, but not an empty zone. So filling ->lowmem_reserve[] for empty zone is not necessary, and may mislead people that it's valid data in that zone. Node 2, zone DMA pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 1024, 1024) Node 2, zone DMA32 pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 1024, 1024) Node 2, zone Normal per-node stats nr_inactive_anon 0 nr_active_anon 143 nr_inactive_file 0 nr_active_file 0 nr_unevictable 0 nr_slab_reclaimable 45 nr_slab_unreclaimable 254 Here clear out zone->lowmem_reserve[] if zone is empty. Link: http://lkml.kernel.org/r/20200402140113.3696-3-bhe@redhat.com Signed-off-by: Baoquan He Signed-off-by: Andrew Morton --- mm/page_alloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/mm/page_alloc.c~mm-page_allocc-clear-out-zone-lowmem_reserve-if-the-zone-is-empty +++ a/mm/page_alloc.c @@ -7704,8 +7704,10 @@ static void setup_per_zone_lowmem_reserv idx--; lower_zone = pgdat->node_zones + idx; - if (!sysctl_lowmem_reserve_ratio[idx]) { + if (!sysctl_lowmem_reserve_ratio[idx] || + !zone_managed_pages(lower_zone)) { lower_zone->lowmem_reserve[j] = 0; + continue; } else { lower_zone->lowmem_reserve[j] = managed_pages / sysctl_lowmem_reserve_ratio[idx];