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Date: Tue, 10 Sep 2013 12:34:41 +0900
From: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To: Toshi Kani <toshi.kani@...com>
CC: <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
<linux-kernel@...r.kernel.org>, <rjw@...k.pl>,
<kosaki.motohiro@...fujitsu.com>, <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH] cpu/mem hotplug: Add try_online_node() for cpu_up()
(2013/09/10 12:31), Yasuaki Ishimatsu wrote:
> (2013/09/10 9:24), Toshi Kani wrote:
>> cpu_up() has #ifdef CONFIG_MEMORY_HOTPLUG code blocks, which
>> call mem_online_node() to put its node online if offlined and
>> then call build_all_zonelists() to initialize the zone list.
>> These steps are specific to memory hotplug, and should be
>> managed in mm/memory_hotplug.c. lock_memory_hotplug() should
>> also be held for the whole steps.
>>
>> For this reason, this patch replaces mem_online_node() with
>> try_online_node(), which performs the whole steps with
>> lock_memory_hotplug() held. try_online_node() is named after
>> try_offline_node() as they have similar purpose.
>>
>> There is no functional change in this patch.
>>
>> Signed-off-by: Toshi Kani <toshi.kani@...com>
>> ---
>> include/linux/memory_hotplug.h | 8 +++++++-
>> kernel/cpu.c | 29 +++--------------------------
>> mm/memory_hotplug.c | 15 +++++++++++++--
>> 3 files changed, 23 insertions(+), 29 deletions(-)
>>
>> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
>> index dd38e62..22203c2 100644
>> --- a/include/linux/memory_hotplug.h
>> +++ b/include/linux/memory_hotplug.h
>> @@ -94,6 +94,8 @@ extern void __online_page_set_limits(struct page *page);
>> extern void __online_page_increment_counters(struct page *page);
>> extern void __online_page_free(struct page *page);
>>
>> +extern int try_online_node(int nid);
>> +
>> #ifdef CONFIG_MEMORY_HOTREMOVE
>> extern bool is_pageblock_removable_nolock(struct page *page);
>> extern int arch_remove_memory(u64 start, u64 size);
>> @@ -225,6 +227,11 @@ static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
>> {
>> }
>>
>> +static inline int try_online_node(int nid)
>> +{
>> + return 0;
>> +}
>> +
>> static inline void lock_memory_hotplug(void) {}
>> static inline void unlock_memory_hotplug(void) {}
>>
>> @@ -256,7 +263,6 @@ static inline void remove_memory(int nid, u64 start, u64 size) {}
>>
>> extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
>> void *arg, int (*func)(struct memory_block *, void *));
>> -extern int mem_online_node(int nid);
>> extern int add_memory(int nid, u64 start, u64 size);
>> extern int arch_add_memory(int nid, u64 start, u64 size);
>> extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
>> diff --git a/kernel/cpu.c b/kernel/cpu.c
>> index d7f07a2..c10b285 100644
>> --- a/kernel/cpu.c
>> +++ b/kernel/cpu.c
>> @@ -420,11 +420,6 @@ int cpu_up(unsigned int cpu)
>> {
>> int err = 0;
>>
>> -#ifdef CONFIG_MEMORY_HOTPLUG
>> - int nid;
>> - pg_data_t *pgdat;
>> -#endif
>> -
>> if (!cpu_possible(cpu)) {
>> printk(KERN_ERR "can't online cpu %d because it is not "
>> "configured as may-hotadd at boot time\n", cpu);
>> @@ -435,27 +430,9 @@ int cpu_up(unsigned int cpu)
>> return -EINVAL;
>> }
>>
>> -#ifdef CONFIG_MEMORY_HOTPLUG
>> - nid = cpu_to_node(cpu);
>> - if (!node_online(nid)) {
>> - err = mem_online_node(nid);
>> - if (err)
>> - return err;
>> - }
>> -
>> - pgdat = NODE_DATA(nid);
>> - if (!pgdat) {
>
>> - printk(KERN_ERR
>> - "Can't online cpu %d due to NULL pgdat\n", cpu);
>
> Please move this comments into try_online_node() too.
In this case, please use pr_err() instead of printk().
Thanks,
Yasuaki Ishimatsu
>
> Thanks,
> Yasuaki Ishimatsu
>
>> - return -ENOMEM;
>> - }
>> -
>> - if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
>> - mutex_lock(&zonelists_mutex);
>> - build_all_zonelists(NULL, NULL);
>> - mutex_unlock(&zonelists_mutex);
>> - }
>> -#endif
>> + err = try_online_node(cpu_to_node(cpu));
>> + if (err)
>> + return err;
>>
>> cpu_maps_update_begin();
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index ed85fe3..c326bdf 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1044,14 +1044,19 @@ static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
>> }
>>
>>
>> -/*
>> +/**
>> + * try_online_node - online a node if offlined
>> + *
>> * called by cpu_up() to online a node without onlined memory.
>> */
>> -int mem_online_node(int nid)
>> +int try_online_node(int nid)
>> {
>> pg_data_t *pgdat;
>> int ret;
>>
>> + if (node_online(nid))
>> + return 0;
>> +
>> lock_memory_hotplug();
>> pgdat = hotadd_new_pgdat(nid, 0);
>> if (!pgdat) {
>> @@ -1062,6 +1067,12 @@ int mem_online_node(int nid)
>> ret = register_one_node(nid);
>> BUG_ON(ret);
>>
>> + if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
>> + mutex_lock(&zonelists_mutex);
>> + build_all_zonelists(NULL, NULL);
>> + mutex_unlock(&zonelists_mutex);
>> + }
>> +
>> out:
>> unlock_memory_hotplug();
>> return ret;
>>
>> --
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>>
>
>
> --
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>
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