From: Oscar Salvador <osalvador@xxxxxxx>
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 <osalvador@xxxxxxx>
---
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
