Re: Strings floppy problem under Linux 2.1.131.

Stephen C. Tweedie (sct@redhat.com)
Tue, 8 Dec 1998 12:18:42 GMT


Hi,

On Mon, 07 Dec 1998 09:25:47 -0500, Michael K Vance <mkv102@psu.edu>
said:

>> "Device is busy" when I was unmounting /dev/fd0. I have verified that
>> there were no processes running at the time. I even changed to the
>> single use mode. I still got "Device is busy" when I was unmounting

> I'm getting consistent "can't unmount '/': device busy" messages
> when I try to reboot: 'shutdown -r 0' (for kernel upgrades, of
> course!), since 2.1.130.

This is a FAQ. New kernels are (correctly) stricter about unmounting
(or rather, remounting read-only) existing filesystems. Specifically,
you can't remount a fs readonly if there are any deleted files still
held open by any processes (because in that case, closing the file
results in an implicit delete of the data, which is illegal if the fs
is readonly).

Some versions of glibc keep /etc/ld.so.cache permanently mapped. If
you run ldconfig with such a glibc, then /sbin/init still keeps a
reference to the old (now deleted) version of ld.so.cache, and so you
cannot remount the root. Newer glibcs unmap the ld.so.cache file
after loading the libraries, so they do not have this problem.

--Stephen

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