On 06/26/2017 04:53 PM, Wei Yang wrote:
> On Mon, Jun 26, 2017 at 12:50:14AM -0700, John Hubbard wrote:
>> On 06/24/2017 07:52 PM, Wei Yang wrote:
[...]
>>
>> Things have changed...the register_new_memory() routine is accepting a single section,
>> but instead of registering just that section, it is registering a containing block.
>> (That works, because apparently the approach is to make sections_per_block == 1,
>> and eventually kill sections, if I am reading all this correctly.)
>>
>
> The original function is a little confusing. Actually it tries to register a
> memory_block while it register it for several times, on each present
> mem_section actually.
>
> This change here will register the whole memory_block at once.
>
> You would see in next patch it will accept the start section number instead of
> a section, while maybe more easy to understand it.
Yes I saw that, and it does help, but even after that, I still thought
we should add that "* Register an entire memory_block." line.
>
> BTW, I don't get your point on kill sections when sections_per_block == The
> original function is a little confusing. Actually it tries to register a
> memory_block while it register it for several times, on each present
> mem_section actually.
>
> This change here will register the whole memory_block at once.
>
> You would see in next patch it will accept the start section number instead of
> a section, while maybe more easy to understand it.
>
> BTW, I don't get your point on kill sections when sections_per_block == 1.
> Would you rephrase this?
>
I was just trying to say, "if I understand correctly, your plan is
to:
Step 1: have one section per block, and then eventually
Step 2: get rid of sections (that's what "kill" meant) entirely."
No big deal, I'm just saying it out loud, to be sure I've got it right.
thanks,
john h
>> So, how about this: let's add a line to the function comment:
>>
>> * Register an entire memory_block.
>>
>
> May look good, let me have a try.
>
>> That makes it clearer that we're dealing in blocks, even though the memsection*
>> argument is passed in.
>>
>>>
>>> - if (mem->section_count == sections_per_block)
>>> - ret = register_mem_sect_under_node(mem, nid);
>>> + ret = register_mem_sect_under_node(mem, nid);
>>> out:
>>> mutex_unlock(&mem_sysfs_mutex);
>>> return ret;
>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>>> index a79a83ec965f..14a08b980b59 100644
>>> --- a/mm/memory_hotplug.c
>>> +++ b/mm/memory_hotplug.c
>>> @@ -302,8 +302,7 @@ void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
>>> }
>>> #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
>>>
>>> -static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
>>> - bool want_memblock)
>>> +static int __meminit __add_section(int nid, unsigned long phys_start_pfn)
>>> {
>>> int ret;
>>> int i;
>>> @@ -332,6 +331,18 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
>>> SetPageReserved(page);
>>> }
>>>
>>> + return 0;
>>> +}
>>> +
>>> +static int __meminit __add_memory_block(int nid, unsigned long phys_start_pfn,
>>> + bool want_memblock)
>>> +{
>>> + int ret;
>>> +
>>> + ret = __add_section(nid, phys_start_pfn);
>>> + if (ret)
>>> + return ret;
>>> +
>>> if (!want_memblock)
>>> return 0;
>>>
>>> @@ -347,15 +358,10 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
>>> int __ref __add_pages(int nid, unsigned long phys_start_pfn,
>>> unsigned long nr_pages, bool want_memblock)
>>> {
>>> - unsigned long i;
>>> + unsigned long pfn;
>>> int err = 0;
>>> - int start_sec, end_sec;
>>> struct vmem_altmap *altmap;
>>>
>>> - /* during initialize mem_map, align hot-added range to section */
>>> - start_sec = pfn_to_section_nr(phys_start_pfn);
>>> - end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
>>> -
>>> altmap = to_vmem_altmap((unsigned long) pfn_to_page(phys_start_pfn));
>>> if (altmap) {
>>> /*
>>> @@ -370,8 +376,9 @@ int __ref __add_pages(int nid, unsigned long phys_start_pfn,
>>> altmap->alloc = 0;
>>> }
>>>
>>> - for (i = start_sec; i <= end_sec; i++) {
>>> - err = __add_section(nid, section_nr_to_pfn(i), want_memblock);
>>> + for (pfn; pfn < phys_start_pfn + nr_pages;
>>> + pfn += sections_per_block * PAGES_PER_SECTION) {
>>
>
> yep
>
>> A pages_per_block variable would be nice here, too.
>>
>> thanks,
>> john h
>>
>>> + err = __add_memory_block(nid, pfn, want_memblock);
>>>
>>> /*
>>> * EEXIST is finally dealt with by ioresource collision
>>>
>
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