Re: [PATCH v3 2/3] mm,memory_hotplug: Implement numa node notifier

[ALOK TIWARI <alok.a.tiwari@oracle.com>]

> -	node_states_set_node(nid, &arg);
> +	node_states_set_node(nid, &node_arg);
>   	if (need_zonelists_rebuild)
>   		build_all_zonelists(NULL);
>   
> @@ -1245,16 +1252,26 @@ int online_pages(unsigned long pfn, unsigned long nr_pages,
>   	kswapd_run(nid);
>   	kcompactd_run(nid);
>   
> +	if (node_arg.status_change_nid >= 0)
> +		/*
> +		 * Node went from memoryless to have memory. Notifiy interested

typo Notifiy -> Notify
"to have memory" /s "to having memory"

> +		 * consumers
> +		 */
> +		node_notify(NODE_BECAME_MEM_AWARE, &node_arg);
> +
>   	writeback_set_ratelimit();
>   
> -	memory_notify(MEM_ONLINE, &arg);
> +	memory_notify(MEM_ONLINE, &mem_arg);
>   	return 0;
>   
>   failed_addition:
>   	pr_debug("online_pages [mem %#010llx-%#010llx] failed\n",
>   		 (unsigned long long) pfn << PAGE_SHIFT,
>   		 (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
> -	memory_notify(MEM_CANCEL_ONLINE, &arg);
> +	if (cancel_mem_notifier_on_err)
> +		memory_notify(MEM_CANCEL_ONLINE, &mem_arg);
> +	if (cancel_node_notifier_on_err)
> +		node_notify(NODE_CANCEL_MEM_AWARE, &node_arg);
>   	remove_pfn_range_from_zone(zone, pfn, nr_pages);
>   	return ret;
>   }
> @@ -1888,48 +1905,29 @@ early_param("movable_node", cmdline_parse_movable_node);
>   
>   /* check which state of node_states will be changed when offline memory */
>   static void node_states_check_changes_offline(unsigned long nr_pages,
> -		struct zone *zone, struct memory_notify *arg)
> +		struct zone *zone, struct node_notify *arg)
>   {
>   	struct pglist_data *pgdat = zone->zone_pgdat;
>   	unsigned long present_pages = 0;
>   	enum zone_type zt;
>   
>   	arg->status_change_nid = NUMA_NO_NODE;
> -	arg->status_change_nid_normal = NUMA_NO_NODE;
>   
>   	/*
> -	 * Check whether node_states[N_NORMAL_MEMORY] will be changed.
> -	 * If the memory to be offline is within the range
> -	 * [0..ZONE_NORMAL], and it is the last present memory there,
> -	 * the zones in that range will become empty after the offlining,
> -	 * thus we can determine that we need to clear the node from
> -	 * node_states[N_NORMAL_MEMORY].
> +	 * Here we count the possible pages within the range [0..ZONE_MOVABLE].
> +	 * If after having accounted all the pages, we see that the nr_pages to
> +	 * be offlined is over or equal to the accounted pages, we know that the
> +	 * node will become empty, ans so, we can clear it for N_MEMORY.

typo ans -> and
"over or equal to the accounted" -> "greater than or equal to the accounted"

>   	 */
> -	for (zt = 0; zt <= ZONE_NORMAL; zt++)
> +	for (zt = 0; zt <= ZONE_MOVABLE; zt++)
>   		present_pages += pgdat->node_zones[zt].present_pages;
> -	if (zone_idx(zone) <= ZONE_NORMAL && nr_pages >= present_pages)
> -		arg->status_change_nid_normal = zone_to_nid(zone);
> -
> -	/*
> -	 * We have accounted the pages from [0..ZONE_NORMAL); ZONE_HIGHMEM
> -	 * does not apply as we don't support 32bit.
> -	 * Here we count the possible pages from ZONE_MOVABLE.
> -	 * If after having accounted all the pages, we see that the nr_pages
> -	 * to be offlined is over or equal to the accounted pages,
> -	 * we know that the node will become empty, and so, we can clear
> -	 * it for N_MEMORY as well.
> -	 */
> -	present_pages += pgdat->node_zones[ZONE_MOVABLE].present_pages;
>   
>   	if (nr_pages >= present_pages)
>   		arg->status_change_nid = zone_to_nid(zone);
>   }
>   
> -static void node_states_clear_node(int node, struct memory_notify *arg)
> +static void node_states_clear_node(int node, struct node_notify *arg)
>   {
> -	if (arg->status_change_nid_normal >= 0)
> -		node_clear_state(node, N_NORMAL_MEMORY);
> -
>   	if (arg->status_change_nid >= 0)
>   		node_clear_state(node, N_MEMORY);
>   }
> @@ -1953,7 +1951,9 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages,
>   	unsigned long pfn, managed_pages, system_ram_pages = 0;
>   	const int node = zone_to_nid(zone);
>   	unsigned long flags;
> -	struct memory_notify arg;
> +	struct memory_notify mem_arg;
> +	struct node_notify node_arg;
> +	bool cancel_mem_notifier_on_err = false, cancel_node_notifier_on_err = false;
>   	char *reason;
>   	int ret;
>   
> @@ -2012,11 +2012,21 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages,
>   		goto failed_removal_pcplists_disabled;
>   	}
>   
> -	arg.start_pfn = start_pfn;
> -	arg.nr_pages = nr_pages;
> -	node_states_check_changes_offline(nr_pages, zone, &arg);
> +	mem_arg.start_pfn = start_pfn;
> +	mem_arg.nr_pages = nr_pages;
> +	node_states_check_changes_offline(nr_pages, zone, &node_arg);
> +
> +	if (node_arg.status_change_nid >= 0) {
> +		cancel_node_notifier_on_err = true;
> +		ret = node_notify(NODE_BECOMING_MEMORYLESS, &node_arg);
> +		ret = notifier_to_errno(ret);
> +		if (ret)
> +			goto failed_removal_isolated;
> +	}
>   
> -	ret = memory_notify(MEM_GOING_OFFLINE, &arg);
> +	cancel_mem_notifier_on_err = true;
> +	mem_arg.status_change_nid = node_arg.status_change_nid;
> +	ret = memory_notify(MEM_GOING_OFFLINE, &mem_arg);
>   	ret = notifier_to_errno(ret);
>   	if (ret) {
>   		reason = "notifier failure";
> @@ -2096,27 +2106,32 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages,
>   	 * Make sure to mark the node as memory-less before rebuilding the zone
>   	 * list. Otherwise this node would still appear in the fallback lists.
>   	 */
> -	node_states_clear_node(node, &arg);
> +	node_states_clear_node(node, &node_arg);
>   	if (!populated_zone(zone)) {
>   		zone_pcp_reset(zone);
>   		build_all_zonelists(NULL);
>   	}
>   
> -	if (arg.status_change_nid >= 0) {
> +	if (node_arg.status_change_nid >= 0) {
>   		kcompactd_stop(node);
>   		kswapd_stop(node);
> +		/* Node went memoryless. Notifiy interested consumers */

typo Notifiy -> Notify

> +		node_notify(NODE_BECAME_MEMORYLESS, &node_arg);
>   	}
>   
>   	writeback_set_ratelimit();
>   
> -	memory_notify(MEM_OFFLINE, &arg);
> +	memory_notify(MEM_OFFLINE, &mem_arg);
>   	remove_pfn_range_from_zone(zone, start_pfn, nr_pages);
>   	return 0;
>   
>   failed_removal_isolated:
>   	/* pushback to free area */
>   	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
> -	memory_notify(MEM_CANCEL_OFFLINE, &arg);
> +	if (cancel_mem_notifier_on_err)
> +		memory_notify(MEM_CANCEL_OFFLINE, &mem_arg);
> +	if (cancel_node_notifier_on_err)
> +		node_notify(NODE_CANCEL_MEMORYLESS, &node_arg);
>   failed_removal_pcplists_disabled:
>   	lru_cache_enable();
>   	zone_pcp_enable(zone);
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index f43951668c41..b3ad63fb3a2b 100644

Thanks,
Alok