Re: [PATCH v3] scripts: add leaking_addresses.pl

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 7 Nov 2017 13:44:01 -0800
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> > Looking other places that stand out, it seems like
> > /proc/lockdep_chains and /proc/lockdep (CONFIG_LOCKDEP=y) has a ton of
> > %p usage. It's unclear to me if a hash is sufficient for meaningful
> > debugging there?  
> 
> Maybe not, but that is also _so_ esoteric that I suspect the right fix
> is to just make it root-only readable.

Also note, I don't believe anyone should be running a LOCKDEP
configured kernel in a production (secured) environment. As it adds
quite a bit of overhead. It's something you run on test environments to
make sure it doesn't detect any possible deadlocks.

> 
> I've never used it, we should check with people who have. I get the
> feeling that this is purely for PeterZ debugging.

I've used it. But then again, I also debug lockdep ;-)

> 
> The very first commit that introduced that code actually has a
> 
>     (FIXME: should go into debugfs)
> 
> so I suspect it never should have been user-readable to begin with. I
> guess it makes some things easier, but it really is *very* different
> from things like profiling.

Want me to whip up a patch to move the file?

-- Steve

> 
> Profiling you often *cannot* do as root - some things you profile
> really shouldn't be run as root, and might even refuse to do so. So
> requiring you to be root just to get a kernel profile is very bad.
> 
> But looking at lockdep stats? Yeah, 'sudo' isn't so big of a deal.
> 
>