userfaultfd: non-cooperative: dup_userfaultfd: use mm_count instead of mm_users

Since commit d2005e3f41d4 ("userfaultfd: don't pin the user memory in
userfaultfd_file_create()") userfaultfd uses mm_count rather than
mm_users to pin mm_struct.

Make dup_userfaultfd consistent with this behaviour

Link: http://lkml.kernel.org/r/20161216144821.5183-11-aarcange@redhat.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 6046e0b552b24d4d1808dfa1c52470ea9fdc70ee..27978f249016f80eb1dbe2c0037e9cc9022d2d4f 100644 (file)
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -558,7 +558,7 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
                ctx->features = octx->features;
                ctx->released = false;
                ctx->mm = vma->vm_mm;
                ctx->features = octx->features;
                ctx->released = false;
                ctx->mm = vma->vm_mm;

-               atomic_inc(&ctx->mm->mm_users);
+               atomic_inc(&ctx->mm->mm_count);

 
                userfaultfd_ctx_get(octx);
                fctx->orig = octx;
 
                userfaultfd_ctx_get(octx);
                fctx->orig = octx;