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From:   Oscar Salvador <osalvador@techadventures.net>
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 <osalvador@suse.de>
Subject: [RFC PATCH 2/5] mm/memory_hotplug: Avoid node_set/clear_state(N_HIGH_MEMORY) when !CONFIG_HIGHMEM
Date:   Wed, 22 Aug 2018 11:32:23 +0200
Message-Id: <20180822093226.25987-3-osalvador@techadventures.net>
In-Reply-To: <20180822093226.25987-1-osalvador@techadventures.net>
References: <20180822093226.25987-1-osalvador@techadventures.net>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Oscar Salvador <osalvador@suse.de>

Currently, when !CONFIG_HIGHMEM, status_change_nid_high is being set
to status_change_nid_normal, but on such systems, N_HIGH_MEMORY equals
N_NORMAL_MEMORY.
That means that if status_change_nid_normal is not -1,
we will perform two calls to node_set_state for the same memory type.

Set status_change_nid_high to -1 for !CONFIG_HIGHMEM, so we skip the
double call in node_states_set_node.

The same goes for node_clear_state.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
 mm/memory_hotplug.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 4a89915e1467..1cfd0b5a9cc7 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -724,7 +724,11 @@ static void node_states_check_changes_online(unsigned long nr_pages,
 	else
 		arg->status_change_nid_high = -1;
 #else
-	arg->status_change_nid_high = arg->status_change_nid_normal;
+	/*
+	 * 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
 
 	/*
@@ -1547,7 +1551,11 @@ static void node_states_check_changes_offline(unsigned long nr_pages,
 	else
 		arg->status_change_nid_high = -1;
 #else
-	arg->status_change_nid_high = arg->status_change_nid_normal;
+	/*
+	 * When !CONFIG_HIGHMEM, N_HIGH_MEMORY equals N_NORMAL_MEMORY
+	 * so clearing the node for N_NORMAL_MEMORY is enough.
+	 */
+	arg->status_change_nid_high = -1;
 #endif
 
 	/*
-- 
2.13.6