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SubjectRe: [PATCH 2/5] mm/memory_hotplug: Avoid node_set/clear_state(N_HIGH_MEMORY) when !CONFIG_HIGHMEM
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On 9/19/18 6:08 AM, Oscar Salvador wrote:
> From: Oscar Salvador <osalvador@suse.de>
>
> Currently, when !CONFIG_HIGHMEM, status_change_nid_high is being set
> to status_change_nid_normal, but on such systems N_HIGH_MEMORY falls
> back to N_NORMAL_MEMORY.
> That means that if status_change_nid_normal is not -1,
> we will perform two calls to node_set_state for the same memory type.
>
> Set status_change_nid_high to -1 for !CONFIG_HIGHMEM, so we skip the
> double call in node_states_set_node.
>
> The same goes for node_clear_state.
>
> Signed-off-by: Oscar Salvador <osalvador@suse.de>

Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>

This is a rare case where I think comments are unnecessary as the code
is self explanatory. So, I would remove the comments before:

> + arg->status_change_nid_high = -1;

Pavel

> ---
> mm/memory_hotplug.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 63facfc57224..c2c7359bd0a7 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -731,7 +731,11 @@ static void node_states_check_changes_online(unsigned long nr_pages,
> else
> arg->status_change_nid_high = -1;
> #else
> - arg->status_change_nid_high = arg->status_change_nid_normal;
> + /*
> + * When !CONFIG_HIGHMEM, N_HIGH_MEMORY equals N_NORMAL_MEMORY
> + * so setting the node for N_NORMAL_MEMORY is enough.
> + */
> + arg->status_change_nid_high = -1;
> #endif
>
> /*
> @@ -1555,7 +1559,11 @@ static void node_states_check_changes_offline(unsigned long nr_pages,
> else
> arg->status_change_nid_high = -1;
> #else
> - arg->status_change_nid_high = arg->status_change_nid_normal;
> + /*
> + * When !CONFIG_HIGHMEM, N_HIGH_MEMORY equals N_NORMAL_MEMORY
> + * so clearing the node for N_NORMAL_MEMORY is enough.
> + */
> + arg->status_change_nid_high = -1;
> #endif
>
> /*
>
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