Yes there are other bugs you will want to fix as well if you are using v6 heavily and not on slow hardware (e.g. a simulator). In the inode allocation route (ialloc()) in /usr/sys/ken/alloc.c there is a bug in the placement of the loop: tag. You just have to move it up two line to above the while() loop. See the diff below. This rare Ken Thompson bug was found in 1988 on an Amdahl UTS machine that the hardware finally became fast enough that it caused us panics. This bug existed from (at least) the Fifth up until the Eighth editions from 1127 (BTL research). The Ninth edition had much rewrites in the kernel and the algorthim was changed at that point. Since it was in UTS, it must have been in the porting base of System V Release 2. This code is the basis for the System V filesystem, so it probably didn't exist in BSD releases since they used their fast filesystem (cylinder groups, et al.) which became UFS. It's amazing thet with the amount of eyes on it (via Lions Commentary, etc.) it was not spotted earlier. It would be good to get a collection of all "unreleased" bug fixes that others may have. *** alloc.c.orig Fri Dec 27 23:23:30 2002 --- alloc.c Fri Dec 27 23:23:30 2002 *************** *** 163,171 **** int i, j, k, ino; fp = getfs(dev); while(fp->s_ilock) sleep(&fp->s_ilock, PINOD); - loop: if(fp->s_ninode > 0) { ino = fp->s_inode[--fp->s_ninode]; ip = iget(dev, ino); --- 163,171 ---- int i, j, k, ino; fp = getfs(dev); + loop: while(fp->s_ilock) sleep(&fp->s_ilock, PINOD); if(fp->s_ninode > 0) { ino = fp->s_inode[--fp->s_ninode]; ip = iget(dev, ino); In article by Mirian Crzig Lennox: