vi core dumping on Sun 2 (fixed, but would like explanations)

[Jim Reno]

Oddly, we recently had a similar problem on a VAX, also with 'vi'.

Since the sticky bit is on, a copy of the text is being maintained
in the swap area (even when nobody is executing it). Later invocations
result in the text being read from the swap area, not the binary
file. Hence if the image in swap has a bad block, it will bomb,
even if the original binary is still good. (Our situation was caused
by a hardware problem in accessing the swap area).

Of course, this just changes the problem to 'why did the swap image
get corrupted?'