On Wed, Aug 22, 2018 at 11:32:26AM +0200, Oscar Salvador wrote:
> From: Oscar Salvador <osalva...@suse.de>
>
> This patch tries to simplify node_states_check_changes_offline
> and make the code more understandable by:
>
> - Removing the if (N_MEMORY == N_NORMAL_MEMORY) wrong statement
> - Removing the if (N_MEMORY == N_HIGH_MEMORY) wrong statement
> - Re-structure the code a bit
> - Removing confusing comments
>
> Signed-off-by: Oscar Salvador <osalva...@suse.de>
I realized I made a mistake here.
I was not counting the present pages correctly.
I will send a new version after the merge-windows gets closed.
Sorry for the noise
For the sake of clarity, the patch should have been:
---
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 006a7b817724..bca11da4e11f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1487,23 +1487,12 @@ static void node_states_check_changes_offline(unsigned
long nr_pages,
enum zone_type zt, 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;
-
- /*
- * check whether node_states[N_NORMAL_MEMORY] will be changed.
- * If the memory to be offline is in a zone of 0...zone_last,
- * and it is the last present memory, 0...zone_last will
- * become empty after offline , thus we can determind we will
- * need to clear the node from node_states[N_NORMAL_MEMORY].
+ * If the current zone is whithin (0..ZONE_NORMAL],
+ * check if the amount of pages that are going to be
+ * offlined is above or equal to the sum of the present
+ * pages of these zones.
+ * If that happens, we need to take this node out of
+ * node_state[N_NORMAL_MEMORY]
*/
for (zt = 0; zt <= zone_last; zt++)
present_pages += pgdat->node_zones[zt].present_pages;
@@ -1514,21 +1503,15 @@ static void node_states_check_changes_offline(unsigned
long nr_pages,
#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.
+ * If the current zone is whithin (0..ZONE_HIGHMEM], check if
+ * the amount of pages that are going to be offlined is above
+ * or equal to the sum of the present pages of these zones.
+ * If that happens, we need to take this node out of
+ * node_state[N_HIGH_MEMORY]
*/
- zone_last = ZONE_HIGHMEM;
- if (N_MEMORY == N_HIGH_MEMORY)
- zone_last = ZONE_MOVABLE;
-
- for (; zt <= zone_last; zt++)
- present_pages += pgdat->node_zones[zt].present_pages;
- if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
+ zt = ZONE_HIGHMEM;
+ present_pages += pgdat->node_zones[zt].present_pages;
+ if (zone_idx(zone) <= zt && nr_pages >= present_pages)
arg->status_change_nid_high = zone_to_nid(zone);
else
arg->status_change_nid_high = -1;
@@ -1541,18 +1524,14 @@ static void node_states_check_changes_offline(unsigned
long nr_pages,
#endif
/*
- * node_states[N_HIGH_MEMORY] contains nodes which have 0...ZONE_MOVABLE
+ * Count pages from ZONE_MOVABLE as well.
+ * If the amount of pages that are going to be offlined is above
+ * or equal the sum of the present pages of all zones, we need
+ * to remove this node from node_state[N_MEMORY]
*/
- zone_last = ZONE_MOVABLE;
+ zt = ZONE_MOVABLE;
+ present_pages += pgdat->node_zones[zt].present_pages;
- /*
- * check whether node_states[N_HIGH_MEMORY] will be changed
- * If we try to offline the last present @nr_pages from the node,
- * we can determind we will need to clear the node from
- * node_states[N_HIGH_MEMORY].
- */
- for (; zt <= zone_last; zt++)
- present_pages += pgdat->node_zones[zt].present_pages;
if (nr_pages >= present_pages)
arg->status_change_nid = zone_to_nid(zone);
else
--
Oscar Salvador
SUSE L3
