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

Andrew Morton
2026-04-03T17:37:21Z

On Thu, 2 Apr 2026 16:59:31 -0700 Anthony Yznaga <anthony.yznaga@oracle.com> wrote:

> 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.

Thanks, I updated mm.git's mm-unstable branch to this version.

In [1/2] I added Mark's Reported.by:. We had David's Acked-by: on v1's
[1/2] patch so I reinstated that.