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

[Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>]

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@xxxxxxxxxxxxxxxxxx>
---
 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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