In D43013#981046, @manu wrote:

Duplicate of https://reviews.freebsd.org/D42793 ?

Address the concerns from @manu:

• the KBI vs. MFC issue
• style(9) errors

Fix style(9) issue.

Address the license issue reported by @emaste.

Address the license issue reported by @emaste.

Address @manu comments.

To tell a bit more about the updated patch: I tracked all uses of GFP_* and verified that the return value was verified. In a few places where the code can't return an error, I replaced GFP_KERNEL with M_WAITOK to make it explicit. vmmap_add() is an example. Another one is the vmalloc*() macros: some of their uses don't check for failures on purpose.

Update patch to:

• Add "ret == NULL" checks in a few places where GFP_KERNEL is used to handle allocation failures.
• Use M_WAITOK explicitly instead of GFP_KERNEL in places where we can't really check the return value or we are not sure it is checked by the caller.