Re: [PATCH 2/3] userfaultfd: non-cooperative: add madvise() event for MADV_REMOVE request

["Hillf Danton" <hillf.zj@alibaba-inc.com>]

On Thursday, January 19, 2017 4:23 PM Mike Rapoport wrote: 
> 
> When a page is removed from a shared mapping, the uffd reader should be
> notified, so that it won't attempt to handle #PF events for the removed
> pages.
> We can reuse the UFFD_EVENT_REMOVE because from the uffd monitor point
> of view, the semantices of madvise(MADV_DONTNEED) and madvise(MADV_REMOVE)
> is exactly the same.
> 
> Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>

>  mm/madvise.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/madvise.c b/mm/madvise.c
> index ab5ef14..0012071 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -520,6 +520,7 @@ static long madvise_remove(struct vm_area_struct *vma,
>  	 * mmap_sem.
>  	 */
>  	get_file(f);
> +	userfaultfd_remove(vma, prev, start, end);
>  	up_read(&current->mm->mmap_sem);
>  	error = vfs_fallocate(f,
>  				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
> --
> 1.9.1

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