Looking at some PRs I found one of them that is very critical:

>Number:         33112
>Category:       kern
>Synopsis:       VND_COMPRESS support broken
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Mar 21 00:25:07 +0000 2006
>Originator:     Julian Bourne
>Release:        3.99.16 (2006-03-09 daily)

I'm not sure what revision broke it, but this one must be fixed for 4.0.

Could any of you that touched the code please take a look at it?

Thanks.