From: Oscar Salvador <osalvador@techadventures.net>
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 <osalvador@suse.de>
Subject: [PATCH v2 3/4] mm/memory_hotplug: Simplify node_states_check_changes_online
Date: Fri, 21 Sep 2018 15:26:33 +0200 [thread overview]
Message-ID: <20180921132634.10103-4-osalvador@techadventures.net> (raw)
In-Reply-To: <20180921132634.10103-1-osalvador@techadventures.net>
From: Oscar Salvador <osalvador@suse.de>
While looking at node_states_check_changes_online, I stumbled
upon some confusing things.
Right after entering the function, we find this:
if (N_MEMORY == N_NORMAL_MEMORY)
zone_last = ZONE_MOVABLE;
This 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_HIGHMEM block, we have:
if (N_MEMORY == N_HIGH_MEMORY)
zone_last = ZONE_MOVABLE;
Again, this is wrong, and will never be evaluated to true.
Besides removing these wrong if statements, I simplified
the function a bit.
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Suggested-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
---
mm/memory_hotplug.c | 57 +++++++----------------------------------------------
1 file changed, 7 insertions(+), 50 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 561c44761f95..eadd149eb7bc 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -687,62 +687,19 @@ 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;
+ arg->status_change_nid = -1;
+ arg->status_change_nid_normal = -1;
+ arg->status_change_nid_high = -1;
- /*
- * 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.
- */
- if (zone_idx(zone) <= zone_last && !node_state(nid, N_NORMAL_MEMORY))
+ if (!node_state(nid, N_MEMORY))
+ arg->status_change_nid = nid;
+ 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.
- */
- 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) <= N_HIGH_MEMORY && !node_state(nid, N_HIGH_MEMORY))
arg->status_change_nid_high = nid;
- else
- arg->status_change_nid_high = -1;
-#else
- arg->status_change_nid_high = arg->status_change_nid_normal;
#endif
-
- /*
- * if the node don't have memory befor online, we will need to
- * set the node to node_states[N_MEMORY] after the memory
- * is online.
- */
- if (!node_state(nid, N_MEMORY))
- arg->status_change_nid = nid;
- else
- arg->status_change_nid = -1;
}
static void node_states_set_node(int node, struct memory_notify *arg)
--
2.13.6
next prev parent reply other threads:[~2018-09-21 13:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 13:26 [PATCH v2 0/4] Refactor node_states_check_changes_online/offline Oscar Salvador
2018-09-21 13:26 ` [PATCH v2 1/4] mm/memory_hotplug: Spare unnecessary calls to node_set_state Oscar Salvador
2018-09-21 13:26 ` [PATCH v2 2/4] mm/memory_hotplug: Tidy up node_states_clear_node Oscar Salvador
2018-09-21 13:26 ` Oscar Salvador [this message]
2018-09-21 14:25 ` [PATCH v2 3/4] mm/memory_hotplug: Simplify node_states_check_changes_online Pasha Tatashin
2018-09-21 13:26 ` [PATCH v2 4/4] mm/memory_hotplug: Clean up node_states_check_changes_offline Oscar Salvador
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