[PATCH v2 0/2] fix MAP_DROPPABLE not supported errno

[Anthony Yznaga]

Mark Brown reported seeing a regression in -next on 32 bit arm with the
mlock selftests. Before exiting and marking the tests failed, the following
message was logged after an attempt to create a MAP_DROPPABLE mapping:

Bail out! mmap error: Unknown error 524

It turns out error 524 is ENOTSUPP which is an error that userspace is not
supposed to see, but it indicates in this instance that MAP_DROPPABLE is
not supported.

The first patch changes the errno returned to EOPNOTSUPP. The second patch
is a second version of a prior patch to introduce selftests to verify
locking behavior with droppable mappings with the additonal change to skip
the tests when MAP_DROPPABLE is not supported.

v2:
- Remove unnecessary mlock() call from selftest (DavidH)
- Change tests to not exit on failure (DavidH)

Anthony Yznaga (2):
  mm: fix mmap errno value when MAP_DROPPABLE is not supported
  selftests/mm: verify droppable mappings cannot be locked

 mm/mmap.c                                 |  2 +-
 tools/testing/selftests/mm/mlock2-tests.c | 87 ++++++++++++++++++++---
 2 files changed, 79 insertions(+), 10 deletions(-)

-- 
2.47.3