[PATCH v1 09/10] mm/memory_hotplug: Don't mark pages PG_reserved when initializing the memmap

[David Hildenbrand]

On 04.11.19 23:44, Boris Ostrovsky wrote:
> On 10/24/19 8:09 AM, David Hildenbrand wrote:
>> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
>> index 4f2e78a5e4db..af69f057913a 100644
>> --- a/drivers/xen/balloon.c
>> +++ b/drivers/xen/balloon.c
>> @@ -374,6 +374,13 @@ static void xen_online_page(struct page *page, unsigned int order)
>>   	mutex_lock(&balloon_mutex);
>>   	for (i = 0; i < size; i++) {
>>   		p = pfn_to_page(start_pfn + i);
>> +		/*
>> +		 * TODO: The core used to mark the pages reserved. Most probably
>> +		 * we can stop doing that now. However, especially
>> +		 * alloc_xenballooned_pages() left PG_reserved set
>> +		 * on pages that can get mapped to user space.
>> +		 */
>> +		__SetPageReserved(p);
> 
> I suspect this is not needed. Pages can get into balloon either from
> here or from non-hotplug path (e.g. decrease_reservation()) and so when
> we get a page from the balloon we would get a random page that may or
> may not have Reserved bit set.

Yeah, I also think it is fine. If you agree, I'll drop this hunk and add 
details to the patch description.


-- 

Thanks,

David / dhildenb