Mark "snaplk" livelock problem as "Needs Testing".
This issue has been fixed by MFC of the following:

src/sys/kern/vfs_bio.c 1.495, 1.496
src/sys/kern/vfs_subr.c 1.648
src/sys/sys/buf.h 1.190, 1.191
src/sys/sys/proc.h 1.436
src/sys/ufs/ffs/ffs_snapshot.c 1.104, 1.105, 1.106

Thanks to: truckman