From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by kanga.kvack.org (Postfix) with ESMTP id ADC8E6B23AE for ; Wed, 22 Aug 2018 05:32:35 -0400 (EDT) Received: by mail-wr1-f70.google.com with SMTP id v11-v6so733186wrn.19 for ; Wed, 22 Aug 2018 02:32:35 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id h19-v6sor299891wmb.88.2018.08.22.02.32.34 for (Google Transport Security); Wed, 22 Aug 2018 02:32:34 -0700 (PDT) From: Oscar Salvador Subject: [RFC PATCH 3/5] mm/memory_hotplug: Simplify node_states_check_changes_online Date: Wed, 22 Aug 2018 11:32:24 +0200 Message-Id: <20180822093226.25987-4-osalvador@techadventures.net> In-Reply-To: <20180822093226.25987-1-osalvador@techadventures.net> References: <20180822093226.25987-1-osalvador@techadventures.net> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: mhocko@suse.com, dan.j.williams@intel.com, malat@debian.org, david@redhat.com, Pavel.Tatashin@microsoft.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Oscar Salvador From: Oscar Salvador While looking at node_states_check_changes_online, I saw some confusing things I am not sure how it was supposed to work. Right after entering the function, we find this: if (N_MEMORY == N_NORMAL_MEMORY) zone_last = ZONE_MOVABLE; This, unless I am missing something really obvious, is wrong. N_MEMORY cannot really be equal to N_NORMAL_MEMORY. My guess is that this wanted to be something like: if (N_NORMAL_MEMORY == N_HIGH_MEMORY) to check if we have CONFIG_HIGHMEM. Later on, in the CONFIG_HICHMEM block, we have: if (N_MEMORY == N_HIGH_MEMORY) zone_last = ZONE_MOVABLE; This is also wrong, and will never be evaluated to true. The thing is that besides this, the function can be simplified a bit. - If the zone is whithin (0..ZONE_NORMAL], we need to set the node for node_state[N_NORMAL_MEMORY] - If we have CONFIG_HIGHMEM, and the zone is within (0..ZONE_NORMAL], we need to set the node for node_state[N_HIGH_MEMORY], as N_HIGH_MEMORY stands for regular or high memory. - Finally, we set the node for node_states[N_MEMORY]. ZONE_MOVABLE ends up there. Signed-off-by: Oscar Salvador --- mm/memory_hotplug.c | 44 +++++++++++++------------------------------- 1 file changed, 13 insertions(+), 31 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 1cfd0b5a9cc7..0f2cf6941224 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -680,46 +680,28 @@ static void node_states_check_changes_online(unsigned long nr_pages, struct zone *zone, struct memory_notify *arg) { int nid = zone_to_nid(zone); - enum zone_type zone_last = ZONE_NORMAL; /* - * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY] - * contains nodes which have zones of 0...ZONE_NORMAL, - * set zone_last to ZONE_NORMAL. - * - * If we don't have HIGHMEM nor movable node, - * node_states[N_NORMAL_MEMORY] contains nodes which have zones of - * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE. - */ - if (N_MEMORY == N_NORMAL_MEMORY) - zone_last = ZONE_MOVABLE; - - /* - * if the memory to be online is in a zone of 0...zone_last, and - * the zones of 0...zone_last don't have memory before online, we will - * need to set the node to node_states[N_NORMAL_MEMORY] after - * the memory is online. + * node_states[N_NORMAL_MEMORY] contains nodes which have + * zones from (0..ZONE_NORMAL] + * We can start checking if the current zone is in that range + * and if so, if the node needs to be set to node_states[N_NORMAL_MEMORY] + * after memory is online. */ - if (zone_idx(zone) <= zone_last && !node_state(nid, N_NORMAL_MEMORY)) + if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY)) arg->status_change_nid_normal = nid; else arg->status_change_nid_normal = -1; #ifdef CONFIG_HIGHMEM /* - * If we have movable node, node_states[N_HIGH_MEMORY] - * contains nodes which have zones of 0...ZONE_HIGHMEM, - * set zone_last to ZONE_HIGHMEM. - * - * If we don't have movable node, node_states[N_NORMAL_MEMORY] - * contains nodes which have zones of 0...ZONE_MOVABLE, - * set zone_last to ZONE_MOVABLE. + * The current zone cannot be ZONE_HIGHMEM, as zone_for_pfn_range + * can only return (0..ZONE_NORMAL] or ZONE_MOVABLE. + * N_HIGH_MEMORY stands for regular or high memory, so if the zone + * is within the range (0..ZONE_NORMAL], we have to set the node + * for N_HIGH_MEMORY as well. */ - zone_last = ZONE_HIGHMEM; - if (N_MEMORY == N_HIGH_MEMORY) - zone_last = ZONE_MOVABLE; - - if (zone_idx(zone) <= zone_last && !node_state(nid, N_HIGH_MEMORY)) + if (zone_idx(zone) < ZONE_HIGHMEM && !node_state(nid, N_HIGH_MEMORY)) arg->status_change_nid_high = nid; else arg->status_change_nid_high = -1; @@ -732,7 +714,7 @@ static void node_states_check_changes_online(unsigned long nr_pages, #endif /* - * if the node don't have memory befor online, we will need to + * if the node don't have memory before online, we will need to * set the node to node_states[N_MEMORY] after the memory * is online. */ -- 2.13.6