Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Improve canonicalization of copyrights. Order copyrights by order of
assertion (jeff, bmilekic, rwatson).

Suggested ages ago by: bde
MFC after: 1 week

Well, it seems that I pre-maturely removed the "All rights reserved"
statement from some files, so re-add it for the moment, until the
related legalese is sorted out. This change affects:

sys/kern/kern_mbuf.c
sys/vm/memguard.c
sys/vm/memguard.h
sys/vm/uma.h
sys/vm/uma_core.c
sys/vm/uma_dbg.c
sys/vm/uma_dbg.h
sys/vm/uma_int.h

/* -> /*- for license, minor formatting changes

Add my copyright and update Jeff's copyright on UMA source files,
as per his request.

Discussed with: Jeffrey Roberson

* Add a "how" argument to uma_zone constructors and initialization functions
so that they know whether the allocation is supposed to be able to sleep
or not.
* Allow uma_zone constructors and initialation functions to return either
success or error. Almost all of the ones in the tree currently return
success unconditionally, but mbuf is a notable exception: the packet
zone constructor wants to be able to fail if it cannot suballocate an
mbuf cluster, and the mbuf allocators want to be able to fail in general
in a MAC kernel if the MAC mbuf initializer fails. This fixes the
panics people are seeing when they run out of memory for mbuf clusters.
* Allow debug.nosleepwithlocks on WITNESS to be disabled, without changing
the default.

Both bmilekic and jeff have reviewed the changes made to make failable
zone allocations work.

- Use my freebsd email alias in the copyright.
- Remove redundant instances of my email alias in the file summary.

Hide a pointer to the malloc_type bucket at the end of the freed memory. If
this memory is modified after it has been freed we can now report it's
previous owner.

Remove the temporary alignment check in free().

Implement the following checks on freed memory in the bucket path:
- Slab membership
- Alignment
- Duplicate free

This previously was only done if we skipped the buckets. This code will slow
down INVARIANTS a bit, but it is smp safe. The checks were moved out of the
normal path and into hooks supplied in uma_dbg.

Add a new UMA debugging facility. This will overwrite freed memory with
0xdeadc0de and then check for it just before memory is handed off as part
of a new request. This will catch any post free/pre alloc modification of
memory, as well as introduce errors for anything that tries to dereference
it as a pointer.

This code takes the form of special init, fini, ctor and dtor routines that
are specificly used by malloc. It is in a seperate file because additional
debugging aids will want to live here as well.