From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id 26E9D6B02AE for ; Wed, 23 May 2018 11:12:24 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id d5-v6so21176986qtg.17 for ; Wed, 23 May 2018 08:12:24 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id q27-v6si1188362qkj.363.2018.05.23.08.12.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 May 2018 08:12:23 -0700 (PDT) From: David Hildenbrand Subject: [PATCH v1 06/10] mm/memory_hotplug: onlining pages can only fail due to notifiers Date: Wed, 23 May 2018 17:11:47 +0200 Message-Id: <20180523151151.6730-7-david@redhat.com> In-Reply-To: <20180523151151.6730-1-david@redhat.com> References: <20180523151151.6730-1-david@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, David Hildenbrand , Andrew Morton , Michal Hocko , Vlastimil Babka , Dan Williams , Reza Arbab , Pavel Tatashin , Thomas Gleixner Onlining pages can only fail if a notifier reported a problem (e.g. -ENOMEM). Remove and restructure error handling. While at it, document how online_pages() can be used right now. Cc: Andrew Morton Cc: Michal Hocko Cc: Vlastimil Babka Cc: Dan Williams Cc: Reza Arbab Cc: Pavel Tatashin Cc: Thomas Gleixner Signed-off-by: David Hildenbrand --- mm/memory_hotplug.c | 47 +++++++++++++++++++++++++++++---------------- 1 file changed, 30 insertions(+), 17 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index c971295a1100..8c0b7d85252b 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -902,7 +902,26 @@ static struct zone * __meminit move_pfn_range(int online_type, int nid, return zone; } -/* Must be protected by mem_hotplug_begin() or a device_lock */ +/** + * online_pages - online pages in a given range (that are currently offline) + * @start_pfn: start pfn of the memory range + * @nr_pages: the number of pages + * @online_type: how to online pages (esp. to which zone to add them) + * + * This function onlines the given pages. Usually, any alignemt / size + * can be used. However, all pages of memory to be removed later on in + * one piece via remove_memory() should be onlined the same way and at + * least the first page should be onlined if anything else is onlined. + * The zone of the first page is used to fixup zones when removing memory + * later on (see __remove_pages()). + * + * Returns 0 if sucessful, an error code if a memory notifier reported a + * problem (e.g. -ENOMEM). + * + * Bad things will happen if pages in the range are already online. + * + * Must be protected by mem_hotplug_begin() or a device_lock + */ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type) { unsigned long flags; @@ -923,8 +942,13 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ ret = memory_notify(MEM_GOING_ONLINE, &arg); ret = notifier_to_errno(ret); - if (ret) - goto failed_addition; + if (ret) { + pr_debug("online_pages [mem %#010llx-%#010llx] failed\n", + (unsigned long long) pfn << PAGE_SHIFT, + (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1); + memory_notify(MEM_CANCEL_ONLINE, &arg); + return ret; + } /* * If this zone is not populated, then it is not in zonelist. @@ -936,13 +960,9 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ setup_zone_pageset(zone); } - ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages, - online_pages_range); - if (ret) { - if (need_zonelists_rebuild) - zone_pcp_reset(zone); - goto failed_addition; - } + /* onlining pages cannot fail */ + walk_system_ram_range(pfn, nr_pages, &onlined_pages, + online_pages_range); zone->present_pages += onlined_pages; @@ -972,13 +992,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ if (onlined_pages) memory_notify(MEM_ONLINE, &arg); return 0; - -failed_addition: - pr_debug("online_pages [mem %#010llx-%#010llx] failed\n", - (unsigned long long) pfn << PAGE_SHIFT, - (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1); - memory_notify(MEM_CANCEL_ONLINE, &arg); - return ret; } #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ -- 2.17.0