Pull the vmlocking changes into a new branch.
Make periphery of sendmsg/recvmsg/sendto/recvfrom MP safe.
apply the following change, which seems to get lost during
vmlocking -> vmlocking2 transition.

	Module Name:    src
	Committed By:   yamt
	Date:           Sun Oct 21 08:23:20 UTC 2007

	Modified Files:
		src/sys/nfs: nfs_socket.c nfs_var.h

	Log Message:
	remove lwp argument from nfs_reconnect and always use &lwp0
	because who triggers a reconnect doesn't really matter here.  PR/37145.


	To generate a diff of this commit:
	cvs rdiff -r1.163 -r1.164 src/sys/nfs/nfs_socket.c
	cvs rdiff -r1.72 -r1.73 src/sys/nfs/nfs_var.h

	Please note that diffs are not public domain; they are subject to the
	copyright notices on the relevant files.
Fix merge botch.
lockdebug_wantlock: put back cpu_intr_p check which disappeared
during vmlocking -> vmlocking2.
lockdebug_mem_check: fix locking.
- Implement and use a very simple spinning reader/writer lock.
- Disable preemption where necessary.
- Make SysV shared memory subsystem MP-safe;
- Replace tsleep/wakeup with condvars;
- Replace malloc with kmem;
- Avoid holding of lock while reallocating;
- Fix the check of last segment when reallocating;
- sys_shmat: unmap if uvm_map_pageable() fails;
- Few cosmetics;

Proposed on <tech-kern>.
Regen syscalls.
Decrease shm_realloc_disable in correct places.
Add memory barriers to previous.
- layer_node_find: fix a race.
- Use kmem_alloc/free.
Mark it MPSAFE.
Reduce coverage of the per-mount lock by using atomic ops.
Fix typo.
Fix merge error.
Reduce unnecessary diffs to HEAD.
Fix merge error.
Fix merge error.
Minor locking fixes.