From: Mike Rapoport <rppt@linux.vnet.ibm.com>
Date: Thu, 16 Nov 2017 01:36:56 +0000 (-0800)
Subject: userfaultfd: use mmgrab instead of open-coded increment of mm_count
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=00bb31fa44acf9591018810ff9d5ab375779c1cc;p=openwrt%2Fstaging%2Fblogic.git

userfaultfd: use mmgrab instead of open-coded increment of mm_count

Link: http://lkml.kernel.org/r/1508132478-7738-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.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 f46d133c0949..ac9a4e65ca49 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -668,7 +668,7 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
 		ctx->features = octx->features;
 		ctx->released = false;
 		ctx->mm = vma->vm_mm;
-		atomic_inc(&ctx->mm->mm_count);
+		mmgrab(ctx->mm);
 
 		userfaultfd_ctx_get(octx);
 		fctx->orig = octx;