From patchwork Thu Apr 16 03:11:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 227951 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=-3.8 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 autolearn=no 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 A33B1C3815B for ; Thu, 16 Apr 2020 03:12:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85CDD208E0 for ; Thu, 16 Apr 2020 03:12:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587006721; bh=BvKioa8lwuWuOYcz+6rQc6W/ASszKvifKTVQtQsB6AU=; h=Date:From:To:Subject:List-ID:From; b=eOR9Lw3KBCQ+tPvVOnBV8W1pFRxSrEheMIbkcmJvfbj+ZeaxbT95YHi6+qXl1onxf lrG6XBkUfeRAoFTPQXhqcKigrWF5h818Cnt5Mnz0gBdby2UMy15GokHJbG/74qpQhK cZw18I6WuIAdiR+p6STVuS9L502X+XnRc33OkLUw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389841AbgDPDMA (ORCPT ); Wed, 15 Apr 2020 23:12:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:52450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389423AbgDPDL7 (ORCPT ); Wed, 15 Apr 2020 23:11:59 -0400 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 31AEA2076D; Thu, 16 Apr 2020 03:11:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587006718; bh=BvKioa8lwuWuOYcz+6rQc6W/ASszKvifKTVQtQsB6AU=; h=Date:From:To:Subject:From; b=hShtKi37u8xaCe5LDWuf2VgWcNxne7mOYATO/3oFZ3oBqUZV+sOiRgF0/tLYCqHGE CFspdIMq2i9qvS+Eu73G+E/JrdXHcXAvluaYm7hAF9t1+zYqqseUUzXPijnkLZ+HmA p+bXc2sEKcXaqU3zftDlPuKAW6PFF6/J+g1zDjBE= Date: Wed, 15 Apr 2020 20:11:57 -0700 From: akpm@linux-foundation.org To: dan.j.williams@intel.com, daniel.m.jordan@oracle.com, david@redhat.com, jmorris@namei.org, ktkhai@virtuozzo.com, mhocko@suse.com, mm-commits@vger.kernel.org, pasha.tatashin@soleen.com, sashal@kernel.org, shile.zhang@linux.alibaba.com, stable@vger.kernel.org, vbabka@suse.cz, yiwei@redhat.com Subject: + mm-initialize-deferred-pages-with-interrupts-enabled.patch added to -mm tree Message-ID: <20200416031157.f_goQGn35%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm: initialize deferred pages with interrupts enabled has been added to the -mm tree. Its filename is mm-initialize-deferred-pages-with-interrupts-enabled.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-initialize-deferred-pages-with-interrupts-enabled.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-initialize-deferred-pages-with-interrupts-enabled.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Pavel Tatashin Subject: mm: initialize deferred pages with interrupts enabled 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 Link: http://lkml.kernel.org/r/20200403140952.17177-3-pasha.tatashin@soleen.com Fixes: 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages") Reported-by: Shile Zhang Signed-off-by: Pavel Tatashin Reviewed-by: Daniel Jordan Acked-by: Michal Hocko Acked-by: Vlastimil Babka Cc: Dan Williams Cc: David Hildenbrand Cc: James Morris Cc: Kirill Tkhai Cc: Sasha Levin Cc: Yiqian Wei Cc: [4.17+] Signed-off-by: Andrew Morton --- include/linux/mmzone.h | 2 ++ mm/page_alloc.c | 20 +++++++------------- 2 files changed, 9 insertions(+), 13 deletions(-) --- a/include/linux/mmzone.h~mm-initialize-deferred-pages-with-interrupts-enabled +++ a/include/linux/mmzone.h @@ -678,6 +678,8 @@ 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~mm-initialize-deferred-pages-with-interrupts-enabled +++ a/mm/page_alloc.c @@ -1843,6 +1843,13 @@ 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; @@ -1865,8 +1872,6 @@ static int __init deferred_init_memmap(v touch_nmi_watchdog(); } 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)); @@ -1909,17 +1914,6 @@ 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. */