Re: [PATCH] mm: Reduce memory bloat with THP

[Nitin Gupta]

On 12/15/17 2:01 AM, Kirill A. Shutemov wrote:
> On Thu, Dec 14, 2017 at 05:28:52PM -0800, Nitin Gupta wrote:
>> diff --git a/mm/madvise.c b/mm/madvise.c
>> index 751e97a..b2ec07b 100644
>> --- a/mm/madvise.c
>> +++ b/mm/madvise.c
>> @@ -508,6 +508,7 @@ static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
>>  					unsigned long start, unsigned long end)
>>  {
>>  	zap_page_range(vma, start, end - start);
>> +	vma->space_efficient = true;
>>  	return 0;
>>  }
>>  
> 
> And this modifies vma without down_write(mmap_sem).
> 

I thought this function was always called with mmmap_sem write locked.
I will check again.

- Nitin