Backport: PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs

Original message:

Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs

With this set, a lot of dangerous operations (chroot, unshare, etc)
become a lot less dangerous because there is no possibility of
subverting privileged binaries.

This patch completely breaks apparmor.  Someone who understands (and
uses) apparmor should fix it or at least give me a hint.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>

Change-Id: I370e8cc0fd6046c0b733c35447698e4e4531454f
mm: remove compressed copy from zram in-memory

Swap subsystem does lazy swap slot free with expecting the page would be
swapped out again so we can avoid unnecessary write.

But the problem in in-memory swap(ex, zram) is that it consumes memory
space until vm_swap_full(ie, used half of all of swap device) condition
meet.  It could be bad if we use multiple swap device, small in-memory
swap and big storage swap or in-memory swap alone.

This patch makes swap subsystem free swap slot as soon as swap-read is
completed and make the swapcache page dirty so the page should be
written out the swap device to reclaim it.  It means we never lose it.

I tested this patch with kernel compile workload.

1. before

   compile time : 9882.42
   zram max wasted space by fragmentation: 13471881 byte
   memory space consumed by zram: 174227456 byte
   the number of slot free notify: 206684

2. after

   compile time : 9653.90
   zram max wasted space by fragmentation: 11805932 byte
   memory space consumed by zram: 154001408 byte
   the number of slot free notify: 426972

[akpm@linux-foundation.org: tweak comment text]
[artem.savkov@gmail.com: fix BUG due to non-swapcache pages in end_swap_bio_read()]
[akpm@linux-foundation.org: invert unlikely() test, augment comment, 80-col cleanup]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Artem Savkov <artem.savkov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Konrad Rzeszutek Wilk <konrad@darnok.org>
Cc: Shaohua Li <shli@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflicts:
	mm/page_io.c

Change-Id: I8f11fb7f0391954435002e7f290352f311c907d4
(cherry picked from commit 40eeed8767d7fba76e45bc462165cb4962472658)