Re: [PATCH 1/3] memory_hotplug: fix stale node_states[N_NORMAL_MEMORY]
From: Ni zhan Chen
Date: Thu Sep 27 2012 - 10:32:29 EST
On 09/27/2012 02:47 PM, Lai Jiangshan wrote:
Currently memory_hotplug only manages the node_states[N_HIGH_MEMORY],
it forgets to manage node_states[N_NORMAL_MEMORY]. it causes
node_states[N_NORMAL_MEMORY] becomes stale.
We add check_nodemasks_changes_online() and check_nodemasks_changes_offline()
to detect whether node_states[N_HIGH_MEMORY] and node_states[N_NORMAL_MEMORY]
are changed while hotpluging.
Also add @status_change_nid_normal to struct memory_notify, thus
the memory hotplug callbacks know whether the node_states[N_NORMAL_MEMORY]
are changed.
I still don't understand why need care N_NORMAL_MEMORY here, could you
explain
in details?
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
---
Documentation/memory-hotplug.txt | 5 ++-
include/linux/memory.h | 1 +
mm/memory_hotplug.c | 94 +++++++++++++++++++++++++++++++------
3 files changed, 83 insertions(+), 17 deletions(-)
diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt
index 6d0c251..6e6cbc7 100644
--- a/Documentation/memory-hotplug.txt
+++ b/Documentation/memory-hotplug.txt
@@ -377,15 +377,18 @@ The third argument is passed by pointer of struct memory_notify.
struct memory_notify {
unsigned long start_pfn;
unsigned long nr_pages;
+ int status_change_nid_normal;
int status_change_nid;
}
start_pfn is start_pfn of online/offline memory.
nr_pages is # of pages of online/offline memory.
+status_change_nid_normal is set node id when N_NORMAL_MEMORY of nodemask
+is (will be) set/clear, if this is -1, then nodemask status is not changed.
status_change_nid is set node id when N_HIGH_MEMORY of nodemask is (will be)
set/clear. It means a new(memoryless) node gets new memory by online and a
node loses all memory. If this is -1, then nodemask status is not changed.
-If status_changed_nid >= 0, callback should create/discard structures for the
+If status_changed_nid* >= 0, callback should create/discard structures for the
node if necessary.
--------------
diff --git a/include/linux/memory.h b/include/linux/memory.h
index ff9a9f8..a09216d 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -53,6 +53,7 @@ int arch_get_memory_phys_device(unsigned long start_pfn);
struct memory_notify {
unsigned long start_pfn;
unsigned long nr_pages;
+ int status_change_nid_normal;
int status_change_nid;
};
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 6a5b90d..b62d429b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -460,6 +460,34 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
return 0;
}
+static void check_nodemasks_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 (N_HIGH_MEMORY == N_NORMAL_MEMORY)
+ zone_last = ZONE_MOVABLE;
+
+ 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;
+
+ if (!node_state(nid, N_HIGH_MEMORY))
+ arg->status_change_nid = nid;
+ else
+ arg->status_change_nid = -1;
+}
+
+static void set_nodemasks(int node, struct memory_notify *arg)
+{
+ if (arg->status_change_nid_normal >= 0)
+ node_set_state(node, N_NORMAL_MEMORY);
+
+ node_set_state(node, N_HIGH_MEMORY);
+}
+
int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
{
@@ -471,13 +499,18 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
struct memory_notify arg;
lock_memory_hotplug();
+ /*
+ * This doesn't need a lock to do pfn_to_page().
+ * The section can't be removed here because of the
+ * memory_block->state_mutex.
+ */
+ zone = page_zone(pfn_to_page(pfn));
+
arg.start_pfn = pfn;
arg.nr_pages = nr_pages;
- arg.status_change_nid = -1;
+ check_nodemasks_changes_online(nr_pages, zone, &arg);
nid = page_to_nid(pfn_to_page(pfn));
- if (node_present_pages(nid) == 0)
- arg.status_change_nid = nid;
ret = memory_notify(MEM_GOING_ONLINE, &arg);
ret = notifier_to_errno(ret);
@@ -487,12 +520,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
return ret;
}
/*
- * This doesn't need a lock to do pfn_to_page().
- * The section can't be removed here because of the
- * memory_block->state_mutex.
- */
- zone = page_zone(pfn_to_page(pfn));
- /*
* If this zone is not populated, then it is not in zonelist.
* This means the page allocator ignores this zone.
* So, zonelist must be updated after online.
@@ -517,7 +544,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
zone->present_pages += onlined_pages;
zone->zone_pgdat->node_present_pages += onlined_pages;
if (onlined_pages) {
- node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
+ set_nodemasks(zone_to_nid(zone), &arg);
if (need_zonelists_rebuild)
build_all_zonelists(NULL, zone);
else
@@ -870,6 +897,44 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
return offlined;
}
+static void check_nodemasks_changes_offline(unsigned long nr_pages,
+ struct zone *zone, struct memory_notify *arg)
+{
+ struct pglist_data *pgdat = zone->zone_pgdat;
+ unsigned long present_pages = 0;
+ enum zone_type zt, zone_last = ZONE_NORMAL;
+
+ if (N_HIGH_MEMORY == N_NORMAL_MEMORY)
+ zone_last = ZONE_MOVABLE;
+
+ for (zt = 0; zt <= zone_last; zt++)
+ present_pages += pgdat->node_zones[zt].present_pages;
+ if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
+ arg->status_change_nid_normal = zone_to_nid(zone);
+ else
+ arg->status_change_nid_normal = -1;
+
+ zone_last = ZONE_MOVABLE;
+ 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
+ arg->status_change_nid = -1;
+}
+
+static void clear_nodemasks(int node, struct memory_notify *arg)
+{
+ if (arg->status_change_nid_normal >= 0)
+ node_clear_state(node, N_NORMAL_MEMORY);
+
+ if (N_HIGH_MEMORY == N_NORMAL_MEMORY)
+ return;
+
+ if (arg->status_change_nid >= 0)
+ node_clear_state(node, N_HIGH_MEMORY);
+}
+
static int __ref offline_pages(unsigned long start_pfn,
unsigned long end_pfn, unsigned long timeout)
{
@@ -903,9 +968,7 @@ static int __ref offline_pages(unsigned long start_pfn,
arg.start_pfn = start_pfn;
arg.nr_pages = nr_pages;
- arg.status_change_nid = -1;
- if (nr_pages >= node_present_pages(node))
- arg.status_change_nid = node;
+ check_nodemasks_changes_offline(nr_pages, zone, &arg);
ret = memory_notify(MEM_GOING_OFFLINE, &arg);
ret = notifier_to_errno(ret);
@@ -973,10 +1036,9 @@ repeat:
if (!populated_zone(zone))
zone_pcp_reset(zone);
- if (!node_present_pages(node)) {
- node_clear_state(node, N_HIGH_MEMORY);
+ clear_nodemasks(node, &arg);
+ if (arg.status_change_nid >= 0)
kswapd_stop(node);
- }
vm_total_pages = nr_free_pagecache_pages();
writeback_set_ratelimit();
--
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