On 6/27/18 9:10 PM, Linus Torvalds wrote:

On Wed, Jun 27, 2018 at 6:45 PM Eric Sandeen [off-list ref] wrote:

quoted

Thus the invalid flag combination of (MAP_SHARED|MAP_PRIVATE) now
passes without error, which is a regression.

It's not a regression, it's just new behavior.

"regression" doesn't mean "things changed". It means "something broke".

What broke?

My commit log perhaps was not clear enough.

What broke is that mmap(MAP_SHARED|MAP_PRIVATE) now succeeds without error,
whereas before it rightly returned -EINVAL.

What behavior should a user expect from a successful mmap(MAP_SHARED|MAP_PRIVATE)?

-Eric

Because if it's some manual page breakage, just fix the manual. That's
what "new behavior" is all about.

There is nothing that says that "MAP_SHARED_VALIDATE" can't work with
just the legacy flags.

Because I'd be worried about your patch breaking some actual new user
of MAP_SHARED_VALIDATE.

Because it's actual *users* of behavior we care about, not some
test-suite or manual pages.

              Linus