swap cache problem in 1.3.12

Todd J Derr (infidel+@pitt.edu)
Thu, 27 Jul 1995 00:17:58 -0400 (EDT)

CC; Linus.Torvalds@Helsinki.FI
well, I would like to have more information to report on this, but since
it doesn't cause anything to really break, it's hard to pinpoint, but my
guess would be something wrong with the mm in fork() or exec().

My system: 386dx40, 4M ram, 20M swap, kernel 1.3.12 compiled as ELF
with hjl's gcc 2.7.0. All my binaries are ELF/libc 5.2.3.

The problem has happened three times since I brough up 1.3.12 tonight, I
type a command to the shell (it happened twice with 'telnet' and once
with 'pppd'), and then I get a stream of:

Jul 26 23:51:11 blue-spray linux: Trying to duplicate nonexistent swap-page
[this is duplicated 30-100 times, and then followed by]
Jul 26 23:51:12 blue-spray linux: Trying to free nonexistent swap-page
[also duplicated 30-100 times]

the counts in each instance of each message don't necessarily seem to
match (it's hard to tell, they come so fast that syslog apparently gets
behind and mangles some of the messages), but all of the 'duplicate'
messages come before the 'free' messages. Also note that no processes
end up dying because of this, the system appears to continue operating
normally, including the process that caused the messages.

I'll try to come up with some more information, but I'm hoping the messages
alone are enough to ring a bell in someone's head.