Re: [PATCH v6 00/11] Kernel address sanitizer - runtime memory debugger.

[Andi Kleen]

> It's a huge pile of tricky code we'll need to maintain.  To justify its
> inclusion I think we need to be confident that kasan will find a
> significant number of significant bugs that
> kmemcheck/debug_pagealloc/slub_debug failed to detect.

I would put it differently. kmemcheck is effectively too slow to run
regularly. kasan is much faster and covers most of kmemcheck.

So I would rather see it as a more practical replacement to
kmemcheck, not an addition.

> How do we get that confidence?  I've seen a small number of
> minorish-looking kasan-detected bug reports go past, maybe six or so. 
> That's in a 20-year-old code base, so one new minor bug discovered per
> three years?  Not worth it!
> 
> Presumably more bugs will be exposed as more people use kasan on
> different kernel configs, but will their number and seriousness justify
> the maintenance effort?

I would expect so. It's also about saving developer time.

IMHO getting better tools like this is the only way to keep
up with growing complexity.

> If kasan will permit us to remove kmemcheck/debug_pagealloc/slub_debug
> then that tips the balance a little.  What's the feasibility of that?

Maybe removing kmemcheck. slub_debug/debug_pagealloc are simple, and are in
different niches (lower overhead debugging)

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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