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 5D8948E0001 for ; Wed, 19 Sep 2018 06:08:40 -0400 (EDT) Received: by mail-wr1-f70.google.com with SMTP id a37-v6so5293357wrc.5 for ; Wed, 19 Sep 2018 03:08:40 -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 x10-v6sor9412482wmg.17.2018.09.19.03.08.39 for (Google Transport Security); Wed, 19 Sep 2018 03:08:39 -0700 (PDT) From: Oscar Salvador Subject: [PATCH 0/5] Refactor node_states_check_changes_online/offline Date: Wed, 19 Sep 2018 12:08:14 +0200 Message-Id: <20180919100819.25518-1-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, 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 From: Oscar Salvador This patchset refactors/clean ups node_states_check_changes_online/offline functions together with node_states_set/clear_node. The main reason behind this patchset is that currently, these functions are suboptimal and confusing. For example, they contain wrong statements like: if (N_MEMORY == N_NORMAL_MEMORY) if (N_MEMORY =! N_NORMAL_MEMORY) if (N_MEMORY != N_HIGH_MEMORY) if (N_MEMORY == N_HIGH_MEMORY) These comparasions are wrong, as N_MEMORY will never be equal to either N_NORMAL_MEMORY or N_HIGH_MEMORY. Although the statements do not "affect" the flow because in the way they are placed, they are completely wrong and confusing. I caught another misuse of this in [1]. Another thing that this patchset addresses is the fact that some functions get called twice, or even unconditionally, without any need. Examples of this are: - node_states_set_node()->node_set_state(node, N_MEMORY) * node_states_set_node() gets called whenever we online pages, so we end up calling node_set_state(node, N_MEMORY) everytime. To avoid this, we should check if the node is already in node_state[N_MEMORY]. - node_states_set_node()->node_set_state(node, N_HIGH_MEMORY) * On !CONFIG_HIGH_MEMORY, N_HIGH_MEMORY == N_NORMAL_MEMORY, but the current code sets: status_change_nid_high = status_change_nid_normal This means that we will call node_set_state(node, N_NORMAL_MEMORY) twice. The fix here is to set status_change_nid_normal = -1 on such systems, so we skip the second call. [1] https://patchwork.kernel.org/patch/10579155/ Oscar Salvador (5): mm/memory_hotplug: Spare unnecessary calls to node_set_state mm/memory_hotplug: Avoid node_set/clear_state(N_HIGH_MEMORY) when !CONFIG_HIGHMEM mm/memory_hotplug: Tidy up node_states_clear_node mm/memory_hotplug: Simplify node_states_check_changes_online mm/memory_hotplug: Clean up node_states_check_changes_offline mm/memory_hotplug.c | 153 +++++++++++++++++++++------------------------------- 1 file changed, 60 insertions(+), 93 deletions(-) -- 2.13.6