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SubjectRe: [PATCH 1/2] mm, memory_hotplug: display allowed zones in the preferred ordering
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On 06/29/2017 09:35 AM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> Prior to "mm, memory_hotplug: do not associate hotadded memory to zones
> until online" we used to allow to change the valid zone types of a
> memory block if it is adjacent to a different zone type. This fact was
> reflected in memoryNN/valid_zones by the ordering of printed zones.
> The first one was default (echo online > memoryNN/state) and the other
> one could be onlined explicitly by online_{movable,kernel}. This
> behavior was removed by the said patch and as such the ordering was
> not all that important. In most cases a kernel zone would be default
> anyway. The only exception is movable_node handled by "mm,
> memory_hotplug: support movable_node for hotpluggable nodes".
>
> Let's reintroduce this behavior again because later patch will remove
> the zone overlap restriction and so user will be allowed to online
> kernel resp. movable block regardless of its placement. Original
> behavior will then become significant again because it would be
> non-trivial for users to see what is the default zone to online into.
>
> Implementation is really simple. Pull out zone selection out of
> move_pfn_range into zone_for_pfn_range helper and use it in
> show_valid_zones to display the zone for default onlining and then
> both kernel and movable if they are allowed. Default online zone is not
> duplicated.

Hm I wouldn't call this maze of functions simple, but seems to be correct.
Maybe Patch 2/2 will simplify the code...

> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

>
> fold me "mm, memory_hotplug: display allowed zones in the preferred ordering"
> ---
> drivers/base/memory.c | 33 +++++++++++++------
> include/linux/memory_hotplug.h | 2 +-
> mm/memory_hotplug.c | 73 ++++++++++++++++++++++++------------------
> 3 files changed, 65 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index c7c4e0325cdb..26383af9900c 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -388,6 +388,22 @@ static ssize_t show_phys_device(struct device *dev,
> }
>
> #ifdef CONFIG_MEMORY_HOTREMOVE
> +static void print_allowed_zone(char *buf, int nid, unsigned long start_pfn,
> + unsigned long nr_pages, int online_type,
> + struct zone *default_zone)
> +{
> + struct zone *zone;
> +
> + if (!allow_online_pfn_range(nid, start_pfn, nr_pages, online_type))
> + return;
> +
> + zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
> + if (zone != default_zone) {
> + strcat(buf, " ");
> + strcat(buf, zone->name);
> + }
> +}
> +
> static ssize_t show_valid_zones(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> @@ -395,7 +411,7 @@ static ssize_t show_valid_zones(struct device *dev,
> unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
> unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
> unsigned long valid_start_pfn, valid_end_pfn;
> - bool append = false;
> + struct zone *default_zone;
> int nid;
>
> /*
> @@ -418,16 +434,13 @@ static ssize_t show_valid_zones(struct device *dev,
> }
>
> nid = pfn_to_nid(start_pfn);
> - if (allow_online_pfn_range(nid, start_pfn, nr_pages, MMOP_ONLINE_KERNEL)) {
> - strcat(buf, default_zone_for_pfn(nid, start_pfn, nr_pages)->name);
> - append = true;
> - }
> + default_zone = zone_for_pfn_range(MMOP_ONLINE_KEEP, nid, start_pfn, nr_pages);
> + strcat(buf, default_zone->name);
>
> - if (allow_online_pfn_range(nid, start_pfn, nr_pages, MMOP_ONLINE_MOVABLE)) {
> - if (append)
> - strcat(buf, " ");
> - strcat(buf, NODE_DATA(nid)->node_zones[ZONE_MOVABLE].name);
> - }
> + print_allowed_zone(buf, nid, start_pfn, nr_pages, MMOP_ONLINE_KERNEL,
> + default_zone);
> + print_allowed_zone(buf, nid, start_pfn, nr_pages, MMOP_ONLINE_MOVABLE,
> + default_zone);
> out:
> strcat(buf, "\n");
>
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index c8a5056a5ae0..5e6e4cc36ff4 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -319,6 +319,6 @@ extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
> unsigned long pnum);
> extern bool allow_online_pfn_range(int nid, unsigned long pfn, unsigned long nr_pages,
> int online_type);
> -extern struct zone *default_zone_for_pfn(int nid, unsigned long pfn,
> +extern struct zone *zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
> unsigned long nr_pages);
> #endif /* __LINUX_MEMORY_HOTPLUG_H */
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index b4015a39d108..6b9a60115e37 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -836,31 +836,6 @@ static void node_states_set_node(int node, struct memory_notify *arg)
> node_set_state(node, N_MEMORY);
> }
>
> -bool allow_online_pfn_range(int nid, unsigned long pfn, unsigned long nr_pages, int online_type)
> -{
> - struct pglist_data *pgdat = NODE_DATA(nid);
> - struct zone *movable_zone = &pgdat->node_zones[ZONE_MOVABLE];
> - struct zone *default_zone = default_zone_for_pfn(nid, pfn, nr_pages);
> -
> - /*
> - * TODO there shouldn't be any inherent reason to have ZONE_NORMAL
> - * physically before ZONE_MOVABLE. All we need is they do not
> - * overlap. Historically we didn't allow ZONE_NORMAL after ZONE_MOVABLE
> - * though so let's stick with it for simplicity for now.
> - * TODO make sure we do not overlap with ZONE_DEVICE
> - */
> - if (online_type == MMOP_ONLINE_KERNEL) {
> - if (zone_is_empty(movable_zone))
> - return true;
> - return movable_zone->zone_start_pfn >= pfn + nr_pages;
> - } else if (online_type == MMOP_ONLINE_MOVABLE) {
> - return zone_end_pfn(default_zone) <= pfn;
> - }
> -
> - /* MMOP_ONLINE_KEEP will always succeed and inherits the current zone */
> - return online_type == MMOP_ONLINE_KEEP;
> -}
> -
> static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
> unsigned long nr_pages)
> {
> @@ -919,7 +894,7 @@ void __ref move_pfn_range_to_zone(struct zone *zone,
> * If no kernel zone covers this pfn range it will automatically go
> * to the ZONE_NORMAL.
> */
> -struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn,
> +static struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn,
> unsigned long nr_pages)
> {
> struct pglist_data *pgdat = NODE_DATA(nid);
> @@ -935,6 +910,31 @@ struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn,
> return &pgdat->node_zones[ZONE_NORMAL];
> }
>
> +bool allow_online_pfn_range(int nid, unsigned long pfn, unsigned long nr_pages, int online_type)
> +{
> + struct pglist_data *pgdat = NODE_DATA(nid);
> + struct zone *movable_zone = &pgdat->node_zones[ZONE_MOVABLE];
> + struct zone *default_zone = default_zone_for_pfn(nid, pfn, nr_pages);
> +
> + /*
> + * TODO there shouldn't be any inherent reason to have ZONE_NORMAL
> + * physically before ZONE_MOVABLE. All we need is they do not
> + * overlap. Historically we didn't allow ZONE_NORMAL after ZONE_MOVABLE
> + * though so let's stick with it for simplicity for now.
> + * TODO make sure we do not overlap with ZONE_DEVICE
> + */
> + if (online_type == MMOP_ONLINE_KERNEL) {
> + if (zone_is_empty(movable_zone))
> + return true;
> + return movable_zone->zone_start_pfn >= pfn + nr_pages;
> + } else if (online_type == MMOP_ONLINE_MOVABLE) {
> + return zone_end_pfn(default_zone) <= pfn;
> + }
> +
> + /* MMOP_ONLINE_KEEP will always succeed and inherits the current zone */
> + return online_type == MMOP_ONLINE_KEEP;
> +}
> +
> static inline bool movable_pfn_range(int nid, struct zone *default_zone,
> unsigned long start_pfn, unsigned long nr_pages)
> {
> @@ -948,12 +948,8 @@ static inline bool movable_pfn_range(int nid, struct zone *default_zone,
> return !zone_intersects(default_zone, start_pfn, nr_pages);
> }
>
> -/*
> - * Associates the given pfn range with the given node and the zone appropriate
> - * for the given online type.
> - */
> -static struct zone * __meminit move_pfn_range(int online_type, int nid,
> - unsigned long start_pfn, unsigned long nr_pages)
> +struct zone * zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
> + unsigned long nr_pages)
> {
> struct pglist_data *pgdat = NODE_DATA(nid);
> struct zone *zone = default_zone_for_pfn(nid, start_pfn, nr_pages);
> @@ -972,6 +968,19 @@ static struct zone * __meminit move_pfn_range(int online_type, int nid,
> zone = &pgdat->node_zones[ZONE_MOVABLE];
> }
>
> + return zone;
> +}
> +
> +/*
> + * Associates the given pfn range with the given node and the zone appropriate
> + * for the given online type.
> + */
> +static struct zone * __meminit move_pfn_range(int online_type, int nid,
> + unsigned long start_pfn, unsigned long nr_pages)
> +{
> + struct zone *zone;
> +
> + zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
> move_pfn_range_to_zone(zone, start_pfn, nr_pages);
> return zone;
> }
>

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