Re: [PATCH v4 2/2] UML: add support for KASAN under x86_64

[Vincent Whitchurch]

On Fri, Jul 01, 2022 at 11:08:27AM +0200, David Gow wrote:
> On Thu, Jun 30, 2022 at 9:29 PM Andrey Konovalov <andreyknvl@xxxxxxxxx> wrote:
> > Stack trace collection code might trigger KASAN splats when walking
> > stack frames, but this can be resolved by using unchecked accesses.
> > The main reason to disable instrumentation here is for performance
> > reasons, see the upcoming patch for arm64 [1] for some details.
> >
> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/commit/?id=802b91118d11
> 
> Ah -- that does it! Using READ_ONCE_NOCHECK() in dump_trace() gets rid
> of the nasty recursive KASAN failures we were getting in the tests.
> 
> I'll send out v5 with those files instrumented again.

Hmm, do we really want that?  In the patch Andrey linked to above he
removed the READ_ONCE_NOCHECK() and added the KASAN_SANITIZE on the
corresponding files for arm64, just like it's already the case in this
patch for UML.