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SubjectRe: [PATCH v10 02/17] x86_64: add KASan support
On Fri, 30 Jan 2015 19:15:42 +0300 Andrey Ryabinin <a.ryabinin@samsung.com> wrote:

> >> --- a/lib/Kconfig.kasan
> >> +++ b/lib/Kconfig.kasan
> >> @@ -5,6 +5,7 @@ if HAVE_ARCH_KASAN
> >>
> >> config KASAN
> >> bool "AddressSanitizer: runtime memory debugger"
> >> + depends on !MEMORY_HOTPLUG
> >> help
> >> Enables address sanitizer - runtime memory debugger,
> >> designed to find out-of-bounds accesses and use-after-free bugs.
> >
> > That's a significant restriction. It has obvious runtime implications.
> > It also means that `make allmodconfig' and `make allyesconfig' don't
> > enable kasan, so compile coverage will be impacted.
> >
> > This wasn't changelogged. What's the reasoning and what has to be done
> > to fix it?
> >
>
> Yes, this is runtime dependency. Hot adding memory won't work.
> Since we don't have shadow for hotplugged memory, kernel will crash on the first access to it.
> To fix this we need to allocate shadow for new memory.
>
> Perhaps it would be better to have a runtime warning instead of Kconfig dependecy?

Is there a plan to get mem-hotplug working with kasan, btw? It doesn't
strike me as very important/urgent. Please add a sentence about this
to the changelog as well.


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