Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932440AbaJaJqe (ORCPT ); Fri, 31 Oct 2014 05:46:34 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:21095 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S932326AbaJaJqa (ORCPT ); Fri, 31 Oct 2014 05:46:30 -0400 X-IronPort-AV: E=Sophos;i="5.04,826,1406563200"; d="scan'208";a="42651928" From: Tang Chen To: , , , , , , , , , , , , , , , , , , , , CC: , , , Gu Zheng Subject: [PATCH 2/2] mem-hotplug: Fix wrong check for zone->pageset initialization in online_pages(). Date: Fri, 31 Oct 2014 17:46:52 +0800 Message-ID: <1414748812-22610-3-git-send-email-tangchen@cn.fujitsu.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1414748812-22610-1-git-send-email-tangchen@cn.fujitsu.com> References: <1414748812-22610-1-git-send-email-tangchen@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.167.226.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When we are doing memory hot-add, the following functions are called: add_memory() |--> hotadd_new_pgdat() |--> free_area_init_node() |--> free_area_init_core() |--> zone->present_pages = realsize; /* 1. zone is populated */ |--> zone_pcp_init() |--> zone->pageset = &boot_pageset; /* 2. zone->pageset is set to boot_pageset */ There are two problems here: 1. Zones could be populated before any memory is onlined. 2. All the zones on a newly added node have the same pageset pointing to boot_pageset. The above two problems will result in the following problem: When we online memory on one node, e.g node2, the following code is executed: online_pages() { ...... if (!populated_zone(zone)) { need_zonelists_rebuild = 1; build_all_zonelists(NULL, zone); } ...... } Because of problem 1, the zone has been populated, and the build_all_zonelists() will never called. zone->pageset won't be updated. Because of problem 2, All the zones on a newly added node have the same pageset pointing to boot_pageset. And as a result, when we online memory on node2, node3's meminfo will corrupt. Pages on node2 may be freed to node3. # for ((i = 2048; i < 2064; i++)); do echo online_movable > /sys/devices/system/node/node2/memory$i/state; done # cat /sys/devices/system/node/node2/meminfo Node 2 MemTotal: 33554432 kB Node 2 MemFree: 33549092 kB Node 2 MemUsed: 5340 kB ...... # cat /sys/devices/system/node/node3/meminfo Node 3 MemTotal: 0 kB Node 3 MemFree: 248 kB /* corrupted */ Node 3 MemUsed: 0 kB ...... We have to populate some zones before onlining memory, otherwise no memory could be onlined. So when onlining pages, we should also check if zone->pageset is pointing to boot_pageset. Signed-off-by: Gu Zheng Signed-off-by: Tang Chen --- include/linux/mm.h | 1 + mm/memory_hotplug.c | 6 +++++- mm/page_alloc.c | 5 +++++ 3 files changed, 11 insertions(+), 1 deletion(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 02d11ee..83e6505 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1732,6 +1732,7 @@ void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...); extern void setup_per_cpu_pageset(void); +extern bool zone_pcp_initialized(struct zone *zone); extern void zone_pcp_update(struct zone *zone); extern void zone_pcp_reset(struct zone *zone); diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 3ab01b2..bc0de0f 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1013,9 +1013,13 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ * If this zone is not populated, then it is not in zonelist. * This means the page allocator ignores this zone. * So, zonelist must be updated after online. + * + * If this zone is populated, zone->pageset could be initialized + * to boot_pageset for the first time a node is added. If so, + * zone->pageset should be allocated. */ mutex_lock(&zonelists_mutex); - if (!populated_zone(zone)) { + if (!populated_zone(zone) || !zone_pcp_initialized(zone)) { need_zonelists_rebuild = 1; build_all_zonelists(NULL, zone); } diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 736d8e1..4ff1540 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6456,6 +6456,11 @@ void __meminit zone_pcp_update(struct zone *zone) } #endif +bool zone_pcp_initialized(struct zone *zone) +{ + return (zone->pageset != &boot_pageset); +} + void zone_pcp_reset(struct zone *zone) { unsigned long flags; -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/