Re: [V4 PATCH 02/26] memory_hotplug: fix missing nodemask management

Wen Congyang
2012-09-11T02:49:52Z

At 09/10/2012 04:58 PM, Lai Jiangshan Wrote:
> Currently memory_hotplug only manages the node_states[N_HIGH_MEMORY],
> it forgot to manage node_states[N_NORMAL_MEMORY]. fix it.
>
> Add check_nodemasks_changes_online() and check_nodemasks_changes_offline
> to detect do node_states[N_HIGH_MEMORY] and node_states[N_NORMAL_MEMORY]
> are changed while hotplug.
>
> Also add @status_change_nid_normal to struct memory_notify, thus
> the memory hotplug callbacks know whether the node_states[N_NORMAL_MEMORY]
> are changed.
>
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
> Documentation/memory-hotplug.txt | 5 ++-
> include/linux/memory.h | 1 +
> mm/memory_hotplug.c | 94 +++++++++++++++++++++++++++++++------
> 3 files changed, 83 insertions(+), 17 deletions(-)
>
> diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt
> index 6d0c251..6e6cbc7 100644
> --- a/Documentation/memory-hotplug.txt
> +++ b/Documentation/memory-hotplug.txt
> @@ -377,15 +377,18 @@ The third argument is passed by pointer of struct memory_notify.
> struct memory_notify {
> unsigned long start_pfn;
> unsigned long nr_pages;
> + int status_change_nid_normal;
> int status_change_nid;
> }
>
> start_pfn is start_pfn of online/offline memory.
> nr_pages is # of pages of online/offline memory.
> +status_change_nid_normal is set node id when N_NORMAL_MEMORY of nodemask
> +is (will be) set/clear, if this is -1, then nodemask status is not changed.
> status_change_nid is set node id when N_HIGH_MEMORY of nodemask is (will be)
> set/clear. It means a new(memoryless) node gets new memory by online and a
> node loses all memory. If this is -1, then nodemask status is not changed.
> -If status_changed_nid >= 0, callback should create/discard structures for the
> +If status_changed_nid* >= 0, callback should create/discard structures for the
> node if necessary.
>
> --------------
> diff --git a/include/linux/memory.h b/include/linux/memory.h
> index 1ac7f6e..6b9202b 100644
> --- a/include/linux/memory.h
> +++ b/include/linux/memory.h
> @@ -53,6 +53,7 @@ int arch_get_memory_phys_device(unsigned long start_pfn);
> struct memory_notify {
> unsigned long start_pfn;
> unsigned long nr_pages;
> + int status_change_nid_normal;
> int status_change_nid;
> };
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 3ad25f9..8c3bcf6 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -456,6 +456,34 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
> return 0;
> }
>
> +static void check_nodemasks_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 (N_HIGH_MEMORY == N_NORMAL_MEMORY)
> + zone_last = ZONE_MOVABLE;
> +
> + if (zone_idx(zone) <= zone_last && !node_state(nid, N_NORMAL_MEMORY))
> + arg->status_change_nid_normal = nid;
> + else
> + arg->status_change_nid_normal = -1;
> +
> + if (!node_state(nid, N_HIGH_MEMORY))
> + arg->status_change_nid = nid;
> + else
> + arg->status_change_nid = -1;
> +}
> +
> +static void set_nodemasks(int node, struct memory_notify *arg)
> +{
> + if (arg->status_change_nid_normal >= 0)
> + node_set_state(node, N_NORMAL_MEMORY);
> +
> + node_set_state(node, N_HIGH_MEMORY);
> +}
> +
>
> int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
> {
> @@ -467,13 +495,18 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
> struct memory_notify arg;
>
> lock_memory_hotplug();
> + /*
> + * This doesn't need a lock to do pfn_to_page().
> + * The section can't be removed here because of the
> + * memory_block->state_mutex.
> + */

If we hotremove memory, we remove the section without memory_block->state_mutex,
it is fixed by the following patch:
https://lkml.org/lkml/2012/9/5/162

Thanks
Wen Congyang

> + zone = page_zone(pfn_to_page(pfn));
> +
> arg.start_pfn = pfn;
> arg.nr_pages = nr_pages;
> - arg.status_change_nid = -1;
> + check_nodemasks_changes_online(nr_pages, zone, &arg);
>
> nid = page_to_nid(pfn_to_page(pfn));
> - if (node_present_pages(nid) == 0)
> - arg.status_change_nid = nid;
>
> ret = memory_notify(MEM_GOING_ONLINE, &arg);
> ret = notifier_to_errno(ret);
> @@ -483,12 +516,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
> return ret;
> }
> /*
> - * This doesn't need a lock to do pfn_to_page().
> - * The section can't be removed here because of the
> - * memory_block->state_mutex.
> - */
> - zone = page_zone(pfn_to_page(pfn));
> - /*
> * If this zone is not populated, then it is not in zonelist.
> * This means the page allocator ignores this zone.
> * So, zonelist must be updated after online.
> @@ -513,7 +540,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
> zone->present_pages += onlined_pages;
> zone->zone_pgdat->node_present_pages += onlined_pages;
> if (onlined_pages) {
> - node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
> + set_nodemasks(zone_to_nid(zone), &arg);
> if (need_zonelists_rebuild)
> build_all_zonelists(NULL, zone);
> else
> @@ -866,6 +893,44 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
> return offlined;
> }
>
> +static void check_nodemasks_changes_offline(unsigned long nr_pages,
> + struct zone *zone, struct memory_notify *arg)
> +{
> + struct pglist_data *pgdat = zone->zone_pgdat;
> + unsigned long present_pages = 0;
> + enum zone_type zt, zone_last = ZONE_NORMAL;
> +
> + if (N_HIGH_MEMORY == N_NORMAL_MEMORY)
> + zone_last = ZONE_MOVABLE;
> +
> + for (zt = 0; zt <= zone_last; zt++)
> + present_pages += pgdat->node_zones[zt].present_pages;
> + if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
> + arg->status_change_nid_normal = zone_to_nid(zone);
> + else
> + arg->status_change_nid_normal = -1;
> +
> + zone_last = ZONE_MOVABLE;
> + for (; zt <= zone_last; zt++)
> + present_pages += pgdat->node_zones[zt].present_pages;
> + if (nr_pages >= present_pages)
> + arg->status_change_nid = zone_to_nid(zone);
> + else
> + arg->status_change_nid = -1;
> +}
> +
> +static void clear_nodemasks(int node, struct memory_notify *arg)
> +{
> + if (arg->status_change_nid_normal >= 0)
> + node_clear_state(node, N_NORMAL_MEMORY);
> +
> + if (N_HIGH_MEMORY == N_NORMAL_MEMORY)
> + return;
> +
> + if (arg->status_change_nid >= 0)
> + node_clear_state(node, N_HIGH_MEMORY);
> +}
> +
> static int __ref offline_pages(unsigned long start_pfn,
> unsigned long end_pfn, unsigned long timeout)
> {
> @@ -899,9 +964,7 @@ static int __ref offline_pages(unsigned long start_pfn,
>
> arg.start_pfn = start_pfn;
> arg.nr_pages = nr_pages;
> - arg.status_change_nid = -1;
> - if (nr_pages >= node_present_pages(node))
> - arg.status_change_nid = node;
> + check_nodemasks_changes_offline(nr_pages, zone, &arg);
>
> ret = memory_notify(MEM_GOING_OFFLINE, &arg);
> ret = notifier_to_errno(ret);
> @@ -969,10 +1032,9 @@ repeat:
> if (!populated_zone(zone))
> zone_pcp_reset(zone);
>
> - if (!node_present_pages(node)) {
> - node_clear_state(node, N_HIGH_MEMORY);
> + clear_nodemasks(node, &arg);
> + if (arg.status_change_nid >= 0)
> kswapd_stop(node);
> - }
>
> vm_total_pages = nr_free_pagecache_pages();
> writeback_set_ratelimit();