From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by kanga.kvack.org (Postfix) with ESMTP id AC44F6B0038 for ; Mon, 24 Aug 2015 05:42:25 -0400 (EDT) Received: by pacti10 with SMTP id ti10so20180486pac.0 for ; Mon, 24 Aug 2015 02:42:25 -0700 (PDT) Received: from heian.cn.fujitsu.com ([59.151.112.132]) by mx.google.com with ESMTP id k12si26553211pbq.59.2015.08.24.02.42.23 for ; Mon, 24 Aug 2015 02:42:24 -0700 (PDT) Message-ID: <55DAE666.5020302@cn.fujitsu.com> Date: Mon, 24 Aug 2015 17:39:50 +0800 From: Tang Chen MIME-Version: 1.0 Subject: Re: [PATCH 2/2] memory-hotplug: remove reset_node_managed_pages() and reset_node_managed_pages() in hotadd_new_pgdat() References: <55C9A3A9.5090300@huawei.com> <55C9A554.4090509@huawei.com> <55D9A036.7060506@cn.fujitsu.com> <55DAE113.20503@huawei.com> In-Reply-To: <55DAE113.20503@huawei.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Xishi Qiu Cc: Andrew Morton , Yasuaki Ishimatsu , Kamezawa Hiroyuki , izumi.taku@jp.fujitsu.com, Linux MM , LKML , Yasuaki Ishimatsu On 08/24/2015 05:17 PM, Xishi Qiu wrote: > On 2015/8/23 18:28, Tang Chen wrote: > >> Hi Shi, >> >> Sorry for the late reply. I hope it won't be too late. >> >> NON-ACK by me, I think. >> >> I noticed that your first has been merged. But it won't fix the problem >> these code intended to fix. >> >> After your patch 1, zone's spanned/present won't be set to 0 because: >> >> free_area_init_node() >> |--> get_pfn_range_for_nid(&start_pfn, &end_pfn) >> |--> calculate_node_totalpages(pgdat, start_pfn, end_pfn, ...) >> | --> zone_spanned_pages_in_node() >> | --> if (!node_start_pfn && !node_end_pfn) return 0; -------- false, won't return 0 >> | --> zone_absent_pages_in_node() >> | --> if (!node_start_pfn && !node_end_pfn) return 0; -------- false, won't return 0 >> > Hi Tang, > > Thank you for your reply. When we add a new node, it is not included in the > memblock, I have no idea why zone_spanned_pages_in_node() and zone_absent_pages_in_node() > won't return 0. Do you add some debug code and print it? Sorry, I didn't say it clearly since I was in a hurry. If we move memblock_add_node() forward before hotadd_new_pgdat(), then node_start_pfn and node_end_pfn won't be 0. And zone_spanned_pages_in_node() and zone_absent_pages_in_node() won't return 0. In your patch, they will return 0. And that leads to the print problem. > >> This is caused by a little bug in your patch 1. >> >> You should put memblock_add_node(start, size, nid) before hotadd_new_pgdat() >> because: >> > My patch is just add an empty node first, later __add_zone() will update the size. > But it is all right put here, and it can fix the print bug. Yes. I just found this bug in the log. > >> hotadd_new_pgdat() >> | --> free_area_init_node() >> | --> get_pfn_range_for_nid() >> | --> find memory ranges in memblock. >> >> | --> memblock_add_node(start, size, nid) ------------------- if you add it here, it doesn't work. >> >> The result will be like below if we hotadd node 5. >> [ 2007.577000] Initmem setup node 5 [mem 0x0000000000000000-0xffffffffffffffff] > pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid, > (u64)start_pfn << PAGE_SHIFT, ((u64)end_pfn << PAGE_SHIFT) - 1); > start_pfn and end_pfn are both 0, and 0-1 -> 0xffffffffffffffff, right? Yes. > >> [ 2007.584000] On node 5 totalpages: 0 >> [ 2007.585000] Built 5 zonelists in Node order, mobility grouping on. Total pages: 32588823 >> [ 2007.594000] Policy zone: Normal >> [ 2007.598000] init_memory_mapping: [mem 0x60000000000-0x607ffffffff] >> >> >> And also, if we merge this patch, /sys/devices/system/node/nodeX/meminfo will break. >> > trigger call trace? No. There is no error output. But if you see /sys/devices/system/node/nodeX/meminfo, memory size will double because totalpages is calculated once here, and one more time when onlining memory. I think reset it to 0 in add_memory() is just a temporary solution. Will improve it in the future. Thanks. > >> Since this patch is not merged, I think let's just drop it. >> >> And about the little bug in your patch 1, since I'm in a hurry, I have already send a patch to fix it. >> >> >> Thanks. :) >> >> >> On 08/11/2015 03:33 PM, Xishi Qiu wrote: >>> After hotadd_new_pgdat()->free_area_init_node(), the pgdat and zone's spanned/present >>> are both 0, so remove reset_node_managed_pages() and reset_node_managed_pages(). >>> >>> Signed-off-by: Xishi Qiu >>> --- >>> mm/memory_hotplug.c | 25 ------------------------- >>> 1 file changed, 25 deletions(-) >>> >>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>> index 11f26cc..997dfad 100644 >>> --- a/mm/memory_hotplug.c >>> +++ b/mm/memory_hotplug.c >>> @@ -1065,16 +1065,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ >>> } >>> #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ >>> -static void reset_node_present_pages(pg_data_t *pgdat) >>> -{ >>> - struct zone *z; >>> - >>> - for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++) >>> - z->present_pages = 0; >>> - >>> - pgdat->node_present_pages = 0; >>> -} >>> - >>> /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */ >>> static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) >>> { >>> @@ -1109,21 +1099,6 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) >>> build_all_zonelists(pgdat, NULL); >>> mutex_unlock(&zonelists_mutex); >>> - /* >>> - * zone->managed_pages is set to an approximate value in >>> - * free_area_init_core(), which will cause >>> - * /sys/device/system/node/nodeX/meminfo has wrong data. >>> - * So reset it to 0 before any memory is onlined. >>> - */ >>> - reset_node_managed_pages(pgdat); >>> - >>> - /* >>> - * When memory is hot-added, all the memory is in offline state. So >>> - * clear all zones' present_pages because they will be updated in >>> - * online_pages() and offline_pages(). >>> - */ >>> - reset_node_present_pages(pgdat); >>> - >>> return pgdat; >>> } >>> >> >> . >> > > > . > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org