PROBLEM:        (QAR 60320)     (Patch ID: OSF375-163)
********
This patch prevents a "kernel memory fault" in the bread() routine
while performing sync operations.

The stack trace will look similar to the following:

0 boot()      ["../../../../src/kernel/arch/alpha/machdep.c"]
1 panic("kernel memory fault") ["../../../../src/kernel/bsd/subr_prf.c"]
2 trap()      ["../../../../src/kernel/arch/alpha/trap.c"]
3 _XentMM()   ["../../../../src/kernel/arch/alpha/locore.s"]
4 bread()     ["../../../../src/kernel/vfs/vfs_bio.c"]
5 iupdat()    ["../../../../src/kernel/ufs/ufs_inode.c"]
6 ufs_sync()  ["../../../../src/kernel/ufs/ufs_vfsops.c";
7 sync()      ["../../../../src/kernel/vfs/vfs_syscalls.c"]
8 syscall()   ["../../../../src/kernel/arch/alpha/syscall_trap.c"]
9 _Xsyscall() ["../../../../src/kernel/arch/alpha/locore.s"]