Re: [PATCH uprobe, thp 3/4] uprobe: support huge page by only splitting the pmd

[Song Liu]

> On May 30, 2019, at 5:14 AM, Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote:
> 
> On Wed, May 29, 2019 at 02:20:48PM -0700, Song Liu wrote:
>> Instead of splitting the compound page with FOLL_SPLIT, this patch allows
>> uprobe to only split pmd for huge pages.
>> 
>> A helper function mm_address_trans_huge(mm, address) was introduced to
>> test whether the address in mm is pointing to THP.
> 
> Maybe it would be cleaner to have FOLL_SPLIT_PMD which would strip
> trans_huge PMD if any and then set pte using get_locked_pte()?

FOLL_SPLIT_PMD sounds like a great idea! Let me try it. 

Thanks,
Song

> 
> This way you'll not need any changes in split_huge_pmd() path. Clearing
> PMD will be fine.
> 
> -- 
> Kirill A. Shutemov