Merge branch 'akpm' (patches from Andrew)HEADmaster

Merge updates from Andrew Morton:

 - a few misc things

 - ocfs2 updates

 - v9fs updates

 - MM

 - procfs updates

 - lib/ updates

 - autofs updates

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (118 commits)
  autofs: small cleanup in autofs_getpath()
  autofs: clean up includes
  autofs: comment on selinux changes needed for module autoload
  autofs: update MAINTAINERS entry for autofs
  autofs: use autofs instead of autofs4 in documentation
  autofs: rename autofs documentation files
  autofs: create autofs Kconfig and Makefile
  autofs: delete fs/autofs4 source files
  autofs: update fs/autofs4/Makefile
  autofs: update fs/autofs4/Kconfig
  autofs: copy autofs4 to autofs
  autofs4: use autofs instead of autofs4 everywhere
  autofs4: merge auto_fs.h and auto_fs4.h
  fs/binfmt_misc.c: do not allow offset overflow
  checkpatch: improve patch recognition
  lib/ucs2_string.c: add MODULE_LICENSE()
  lib/mpi: headers cleanup
  lib/percpu_ida.c: use _irqsave() instead of local_irq_save() + spin_lock
  lib/idr.c: remove simple_ida_lock
  lib/bitmap.c: micro-optimization for __bitmap_complement()
  ...

1 files changed, 17 insertions, 5 deletions

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 39791b81ede7f..5029f241908f4 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -404,7 +404,8 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
 					      unsigned long dst_start,
 					      unsigned long src_start,
 					      unsigned long len,
-					      bool zeropage)
+					      bool zeropage,
+					      bool *mmap_changing)
 {
 	struct vm_area_struct *dst_vma;
 	ssize_t err;
@@ -431,6 +432,15 @@ retry:
 	down_read(&dst_mm->mmap_sem);
 
 	/*
+	 * If memory mappings are changing because of non-cooperative
+	 * operation (e.g. mremap) running in parallel, bail out and
+	 * request the user to retry later
+	 */
+	err = -EAGAIN;
+	if (mmap_changing && READ_ONCE(*mmap_changing))
+		goto out_unlock;
+
+	/*
 	 * Make sure the vma is not shared, that the dst range is
 	 * both valid and fully within a single existing vma.
 	 */
@@ -563,13 +573,15 @@ out:
 }
 
 ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
-		     unsigned long src_start, unsigned long len)
+		     unsigned long src_start, unsigned long len,
+		     bool *mmap_changing)
 {
-	return __mcopy_atomic(dst_mm, dst_start, src_start, len, false);
+	return __mcopy_atomic(dst_mm, dst_start, src_start, len, false,
+			      mmap_changing);
 }
 
 ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
-		       unsigned long len)
+		       unsigned long len, bool *mmap_changing)
 {
-	return __mcopy_atomic(dst_mm, start, 0, len, true);
+	return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing);
 }