RE: [PATCH 05/12] mm, thp, tmpfs: request huge page in shm_fault when needed

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

Ning Qu wrote:
> Add the function to request huge page in shm_fault when needed.
> And it will fall back to regular page if huge page can't be
> satisfied or allocated.
> 
> If small page requested but huge page is found, the huge page will
> be splitted.
> 
> Signed-off-by: Ning Qu <quning@gmail.com>
> ---
>  mm/shmem.c | 32 +++++++++++++++++++++++++++++---
>  1 file changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 68a0e1d..2fc450d 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1472,19 +1472,45 @@ unlock:
>  static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  {
>  	struct inode *inode = file_inode(vma->vm_file);
> +	struct page *page = NULL;
>  	int error;
>  	int ret = VM_FAULT_LOCKED;
>  	gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
> -
> -	error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, gfp,
> -				0, &ret);
> +	bool must_use_thp = vmf->flags & FAULT_FLAG_TRANSHUGE;
> +	int flags = 0;
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE
> +	flags |= AOP_FLAG_TRANSHUGE;
> +#endif

ifdef is not needed: shmem_getpage will ignore AOP_FLAG_TRANSHUGE if
CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE is not defined.

-- 
 Kirill A. Shutemov

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