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[62.201.165.239]) by smtp.gmail.com with ESMTPSA id b10-v6sm16530345wrr.88.2018.09.19.03.08.39 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Sep 2018 03:08:39 -0700 (PDT) Received: from d104.suse.de (charybdis-ext.suse.de [195.135.221.2]) by techadventures.net (Postfix) with ESMTPA id 70E981253C5; Wed, 19 Sep 2018 12:08:38 +0200 (CEST) From: Oscar Salvador To: akpm@linux-foundation.org Cc: mhocko@suse.com, dan.j.williams@intel.com, david@redhat.com, Pavel.Tatashin@microsoft.com, Jonathan.Cameron@huawei.com, yasu.isimatu@gmail.com, malat@debian.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador Subject: [PATCH 4/5] mm/memory_hotplug: Simplify node_states_check_changes_online Date: Wed, 19 Sep 2018 12:08:18 +0200 Message-Id: <20180919100819.25518-5-osalvador@techadventures.net> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20180919100819.25518-1-osalvador@techadventures.net> References: <20180919100819.25518-1-osalvador@techadventures.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oscar Salvador While looking at node_states_check_changes_online, I stumbled upon some confusing things. Right after entering the function, we find this: if (N_MEMORY == N_NORMAL_MEMORY) zone_last = ZONE_MOVABLE; This 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_HIGHMEM block, we have: if (N_MEMORY == N_HIGH_MEMORY) zone_last = ZONE_MOVABLE; Again, this is wrong, and will never be evaluated to true. Besides removing these wrong if statements, I simplified the function a bit. Signed-off-by: Oscar Salvador --- mm/memory_hotplug.c | 71 +++++++++++++++++------------------------------------ 1 file changed, 23 insertions(+), 48 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 131c08106d54..ab3c1de18c5d 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -687,61 +687,36 @@ 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. + * zone_for_pfn_range() can only return a zone within + * (0..ZONE_NORMAL] or ZONE_MOVABLE. + * If the zone is within the range (0..ZONE_NORMAL], + * we need to check if: + * 1) We need to set the node for N_NORMAL_MEMORY + * 2) On CONFIG_HIGHMEM systems, we need to also set + * the node for N_HIGH_MEMORY. + * 3) On !CONFIG_HIGHMEM, we can disregard N_HIGH_MEMORY, + * as N_HIGH_MEMORY falls back to N_NORMAL_MEMORY. */ - 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. - */ - if (zone_idx(zone) <= zone_last && !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. - */ - zone_last = ZONE_HIGHMEM; - if (N_MEMORY == N_HIGH_MEMORY) - zone_last = ZONE_MOVABLE; + if (zone_idx(zone) <= ZONE_NORMAL) { + if (!node_state(nid, N_NORMAL_MEMORY)) + arg->status_change_nid_normal = nid; + else + arg->status_change_nid_normal = -1; - if (zone_idx(zone) <= zone_last && !node_state(nid, N_HIGH_MEMORY)) - arg->status_change_nid_high = nid; - else - arg->status_change_nid_high = -1; -#else - /* - * When !CONFIG_HIGHMEM, N_HIGH_MEMORY equals N_NORMAL_MEMORY - * so setting the node for N_NORMAL_MEMORY is enough. - */ - arg->status_change_nid_high = -1; -#endif + if (IS_ENABLED(CONFIG_HIGHMEM)) { + if (!node_state(nid, N_HIGH_MEMORY)) + arg->status_change_nid_high = nid; + } else + arg->status_change_nid_high = -1; + } /* - * if the node don't have memory befor online, we will need to - * set the node to node_states[N_MEMORY] after the memory - * is online. + * if the node doesn't have memory before onlining it, we will need + * to set the node to node_states[N_MEMORY] after the memory + * gets onlined. */ if (!node_state(nid, N_MEMORY)) arg->status_change_nid = nid; -- 2.13.6