Merge origin/chromeos-4.19-lowmem

Total number of patches against baseline: 367

Merge log:

----------------------------------------------------------------
Ben Cheng (1):
      CHROMIUM: low_mem: fix file_size underflow

Cheng-Yu Lee (1):
      CHROMIUM: Consider min_free_kbytes in low memory notification.

Guenter Roeck (2):
      CHROMIUM: low_mem: Use get_nr_swap_pages()
      Merge origin/chromeos-4.19-lowmem

Jongseok Kim (1):
      FROMLIST: z3fold: fix wrong handling of headless pages

Justin TerAvest (1):
      CHROMIUM: low-mem: Add "available" sysfs file.

Kuo-Hsin Yang (4):
      CHROMIUM: mm: Allow file page scanning when swapping is disabled.
      CHROMIUM: low_mem: use enum node_stat_item directly to get memory status
      CHROMIUM: low_mem: notify low memory when anonymous is low
      CHROMIUM: low_mem: log low memory notification with rate limit

Luigi Semenzato (9):
      CHROMIUM: Add /dev/low-mem device for low-memory notification.
      CHROMIUM: low-mem: improve detection of low-memory conditions.
      CHROMIUM: low-mem: Fix incorrect logging in debug code for low-mem-notify.
      CHROMIUM: low-mem: fix sign of free memory calculation.
      CHROMIUM: change low-mem to chromeos-low-mem in /sys/kernel/mm.
      CHROMIUM: low-mem notifier: lower default, change units, enable disabling
      CHROMIUM: low-mem: add "on" command and fix error case
      CHROMIUM: low-mem: work with swap enabled
      CHROMIUM: low_mem: make ram_vs_swap_weight configurable

Mandeep Singh Baines (1):
      CHROMIUM: vmscan: add min_filelist_kbytes sysctl for protecting the working set

Sonny Rao (2):
      CHROMIUM: mm: lower oom dump burst limit to 1
      CHROMIUM: mm: low-mem-notify: fix LRU counter usage for 4.14

Vovo Yang (1):
      CHROMIUM: mm: vmscan: Fix redundant scan loop when file page count is low

Will Drewry (2):
      CHROMIUM: Restrict swapon() to "zram" devices / lock down zram
      CHROMIUM: mmap, sysctl: add sysctl for controlling VM_MAYEXEC taint

 drivers/block/zram/zram_drv.c  |  40 +++++++-
 drivers/block/zram/zram_drv.h  |   4 +
 drivers/char/mem.c             |   4 +
 include/linux/low-mem-notify.h | 101 +++++++++++++++++++
 include/linux/mm.h             |   7 ++
 init/Kconfig                   |   9 ++
 kernel/sysctl.c                |  27 +++++
 mm/Kconfig                     |  28 ++++++
 mm/Makefile                    |   1 +
 mm/low-mem-notify.c            | 223 +++++++++++++++++++++++++++++++++++++++++
 mm/mmap.c                      |   3 +-
 mm/oom_kill.c                  |   2 +-
 mm/page_alloc.c                |   6 ++
 mm/swapfile.c                  |  44 ++++++--
 mm/util.c                      |   1 +
 mm/vmscan.c                    |  33 ++++++
 mm/z3fold.c                    |   8 +-
 tools/mm/low-mem-test.c        | 178 ++++++++++++++++++++++++++++++++
 18 files changed, 701 insertions(+), 18 deletions(-)
 create mode 100644 include/linux/low-mem-notify.h
 create mode 100644 mm/low-mem-notify.c
 create mode 100644 tools/mm/low-mem-test.c

BUG=chromium:885330
TEST=After completed merge, load resulting image on target system

Change-Id: Ie74ddb79f2ad4dc30d0a0e301c51be43bd7227fe
Signed-off-by: Guenter Roeck <groeck@chromium.org>