[PATCH] Fix kallsyms/insmod/rmmod race

[David Howells]

David Howells <dhowells at redhat.com> wrote:

> Rusty Russell <rusty at rustcorp.com.au> wrote:
> 
> > 	The more I looked at this, the more I warmed to it.  I've known for a
> > while that people are using kallsyms not for OOPS (eg. /proc/$$/wchan),
> > so we should provide a "grabs locks" version, but this solution gets
> > around that nicely, while making life more certain for the oops case,
> > too.
> 
> Hmmm... though it works on i386 SMP, it doesn't, however, seem to work on
> ppc64 SMP:-/
> 
> My pSeries box seems to think that it can't find any symbols from previously
> loaded modules, and my Power5 box is quite happy to load modules that depend
> on other modules but panics because it can't mount its root fs.

Turns out that the patch works. Userspace was being bad. The stripped down
shell running as init (pid #1) wasn't taking into account that it would get
notification of kernel threads exiting when it called wait(), and so ended up
trying to load several modules at once, some of which required dependency
modules loading first.

David