Commit 8efe33f4 authored by Oscar Salvador's avatar Oscar Salvador Committed by Linus Torvalds
Browse files

mm/memory_hotplug.c: simplify node_states_check_changes_online 

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.

[osalvador@suse.de: address feedback from Pavel]
  Link: http://lkml.kernel.org/r/20180921132634.10103-4-osalvador@techadventures.net
Link: http://lkml.kernel.org/r/20180919100819.25518-5-osalvador@techadventures.net


Signed-off-by: default avatarOscar Salvador <osalvador@suse.de>
Reviewed-by: default avatarPavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <yasu.isimatu@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cf01f6f5

mm/memory_hotplug.c

+7 −50
Original line number Diff line number Diff line
@@ -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;



	/*

	 * 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))

		arg->status_change_nid_normal = nid;

	else

	arg->status_change_nid = -1;

	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))

		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;

	if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY))

		arg->status_change_nid_normal = nid;

#ifdef CONFIG_HIGHMEM

	if (zone_idx(zone) <= N_HIGH_MEMORY && !node_state(nid, N_HIGH_MEMORY))

		arg->status_change_nid_high = nid;

#endif

}



static void node_states_set_node(int node, struct memory_notify *arg)

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