mm/munlock: delete munlock_vma_pages_all(), allow oomreap

munlock_vma_pages_range() will still be required, when munlocking but
not munmapping a set of pages; but when unmapping a pte, the mlock count
will be maintained in much the same way as it will be maintained when
mapping in the pte.  Which removes the need for munlock_vma_pages_all()
on mlocked vmas when munmapping or exiting: eliminating the catastrophic
contention on i_mmap_rwsem, and the need for page lock on the pages.

There is still a need to update locked_vm accounting according to the
munmapped vmas when munmapping: do that in detach_vmas_to_be_unmapped().
exit_mmap() does not need locked_vm updates, so delete unlock_range().

And wasn't I the one who forbade the OOM reaper to attack mlocked vmas,
because of the uncertainty in blocking on all those page locks?
No fear of that now, so permit the OOM reaper on mlocked vmas.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
index aec4ce7919da..5d7ced8303be 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -137,8 +137,8 @@ void munlock_vma_page(struct page *page)
  * Returns with VM_LOCKED cleared.  Callers must be prepared to
  * deal with this.
  */
-void munlock_vma_pages_range(struct vm_area_struct *vma,
-			     unsigned long start, unsigned long end)
+static void munlock_vma_pages_range(struct vm_area_struct *vma,
+				    unsigned long start, unsigned long end)
 {
 	vma->vm_flags &= VM_LOCKED_CLEAR_MASK;