ksm: check and skip page, if it is already scanned

On system like Android where most of the process are forked
from parent w/o execve, KSM can scan same page multiple times
in one scan cycle. There is no advantage in scanning same page
multiple times for merging. During testing with Android, it was
observed around 60% pages are skipped for each scan cycle.

Change-Id: I0cf01802f0b4d61fcab92558beb9e1c660dc9a77
Link: http://lkml.kernel.org/r/CAMrOTPgBtANS_ryRjan0-dTL97U7eRvtf3dCsss=Kn+Uk89fuA@mail.gmail.com
Signed-off-by: Pradeep Sawlani <sawlani@amazon.com>

Signed-off-by: Paul Reioux <reioux@gmail.com>

Conflicts:
	include/linux/page-flags.h
ext4: fix memory leak in xattr

If we take the 2nd retry path in ext4_expand_extra_isize_ea, we
potentionally return from the function without having freed these
allocations.  If we don't do the return, we over-write the previous
allocation pointers, so we leak either way.

Spotted with Coverity.

[ Fixed by tytso to set is and bs to NULL after freeing these
  pointers, in case in the retry loop we later end up triggering an
  error causing a jump to cleanup, at which point we could have a double
  free bug. -- Ted ]

Change-Id: I49b8ca41a6c6d44b563eb23306870258a3affd3b
Signed-off-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable@vger.kernel.org
Git-commit: 6e4ea8e33b2057b85d75175dd89b93f5e26de3bc
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>

Conflicts:
	fs/ext4/xattr.c