Introduce ZramWriteback

This implements the basic logic of periodical zram writeback.
mmd marks pages in zram as idle which have been in zram for more than a
specified duration between min_idle and max_idle.

The logic mainly comes from swap_management of ChromeOS.

Bug: 375432468
Test: atest mmd_unit_tests

Change-Id: I2d2a5bcabd7f2632d5707f001547d5052f3f8a3a
11 files changed
tree: dc073a9268985f179f286af515bdd084fc21a09e
  1. aidl/
  2. src/
  3. .gitignore
  4. Android.bp
  5. flags.aconfig
  6. mmd.rc
  7. OWNERS
  8. PREUPLOAD.cfg
  9. TEST_MAPPING