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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 EC8FCC433E0 for ; Fri, 19 Jun 2020 15:12:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3C0721582 for ; Fri, 19 Jun 2020 15:12:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592579535; bh=mvP8PbU7TdCifdkIMd1Es8azRYI9/CbpylWsdkoFvAo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=vlmY2H/nYVPugOH0fUAhFQx8wwiuTrj7RpMxcLtT5f/CBEgmX0IopR05PNqoC56/L 2CQYr5rNdCvKb/D3FbrhhL984nL5Tx+7EeQDbvhDKOWeCDF5VzKghkUc4qFU/4/LfG p7ax80LGYcWNCV8tgWgw8rC0gn/z45KIG6MiMbBA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391863AbgFSPMO (ORCPT ); Fri, 19 Jun 2020 11:12:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:42538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403871AbgFSPMJ (ORCPT ); Fri, 19 Jun 2020 11:12:09 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 D42E02186A; Fri, 19 Jun 2020 15:12:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592579528; bh=mvP8PbU7TdCifdkIMd1Es8azRYI9/CbpylWsdkoFvAo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bxiP2Ye6hbhAYNG6tzF54PBvCvjnemTRVkLeI4LaTLxYqWMdpZyNzoFSaNCiWgny0 Ah+7rhcbQSk18rG97mTYOM3MGEM5sdx3X+QlSLAjV768NvD2Psywao+dLEfP4Sxaxu 9gjkMTdAu4aN8CSGlSfThWklKOJf6Em75GrfkVU0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shile Zhang , Pavel Tatashin , Andrew Morton , Daniel Jordan , David Hildenbrand , Michal Hocko , Vlastimil Babka , Dan Williams , James Morris , Kirill Tkhai , Sasha Levin , Yiqian Wei , Linus Torvalds Subject: [PATCH 5.4 170/261] mm: initialize deferred pages with interrupts enabled Date: Fri, 19 Jun 2020 16:33:01 +0200 Message-Id: <20200619141658.052756597@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141649.878808811@linuxfoundation.org> References: <20200619141649.878808811@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Tatashin commit 3d060856adfc59afb9d029c233141334cfaba418 upstream. Initializing struct pages is a long task and keeping interrupts disabled for the duration of this operation introduces a number of problems. 1. jiffies are not updated for long period of time, and thus incorrect time is reported. See proposed solution and discussion here: lkml/20200311123848.118638-1-shile.zhang@linux.alibaba.com 2. It prevents farther improving deferred page initialization by allowing intra-node multi-threading. We are keeping interrupts disabled to solve a rather theoretical problem that was never observed in real world (See 3a2d7fa8a3d5). Let's keep interrupts enabled. In case we ever encounter a scenario where an interrupt thread wants to allocate large amount of memory this early in boot we can deal with that by growing zone (see deferred_grow_zone()) by the needed amount before starting deferred_init_memmap() threads. Before: [ 1.232459] node 0 initialised, 12058412 pages in 1ms After: [ 1.632580] node 0 initialised, 12051227 pages in 436ms Fixes: 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages") Reported-by: Shile Zhang Signed-off-by: Pavel Tatashin Signed-off-by: Andrew Morton Reviewed-by: Daniel Jordan Reviewed-by: David Hildenbrand Acked-by: Michal Hocko Acked-by: Vlastimil Babka Cc: Dan Williams Cc: James Morris Cc: Kirill Tkhai Cc: Sasha Levin Cc: Yiqian Wei Cc: [4.17+] Link: http://lkml.kernel.org/r/20200403140952.17177-3-pasha.tatashin@soleen.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/mmzone.h | 2 ++ mm/page_alloc.c | 20 +++++++------------- 2 files changed, 9 insertions(+), 13 deletions(-) --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -709,6 +709,8 @@ typedef struct pglist_data { /* * Must be held any time you expect node_start_pfn, * node_present_pages, node_spanned_pages or nr_zones to stay constant. + * Also synchronizes pgdat->first_deferred_pfn during deferred page + * init. * * pgdat_resize_lock() and pgdat_resize_unlock() are provided to * manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1793,6 +1793,13 @@ static int __init deferred_init_memmap(v BUG_ON(pgdat->first_deferred_pfn > pgdat_end_pfn(pgdat)); pgdat->first_deferred_pfn = ULONG_MAX; + /* + * Once we unlock here, the zone cannot be grown anymore, thus if an + * interrupt thread must allocate this early in boot, zone must be + * pre-grown prior to start of deferred page initialization. + */ + pgdat_resize_unlock(pgdat, &flags); + /* Only the highest zone is deferred so find it */ for (zid = 0; zid < MAX_NR_ZONES; zid++) { zone = pgdat->node_zones + zid; @@ -1813,8 +1820,6 @@ static int __init deferred_init_memmap(v while (spfn < epfn) nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn); zone_empty: - pgdat_resize_unlock(pgdat, &flags); - /* Sanity check that the next zone really is unpopulated */ WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone)); @@ -1857,17 +1862,6 @@ deferred_grow_zone(struct zone *zone, un pgdat_resize_lock(pgdat, &flags); /* - * If deferred pages have been initialized while we were waiting for - * the lock, return true, as the zone was grown. The caller will retry - * this zone. We won't return to this function since the caller also - * has this static branch. - */ - if (!static_branch_unlikely(&deferred_pages)) { - pgdat_resize_unlock(pgdat, &flags); - return true; - } - - /* * If someone grew this zone while we were waiting for spinlock, return * true, as there might be enough pages already. */