Re: [PATCH v2 13/33] kmsan: Introduce memset_no_sanitize_memory()

[Ilya Leoshkevich]

On Wed, 2023-12-13 at 02:31 +0100, Ilya Leoshkevich wrote:
> On Fri, 2023-12-08 at 16:25 +0100, Alexander Potapenko wrote:
> > > A problem with __memset() is that, at least for me, it always
> > > ends
> > > up being a call. There is a use case where we need to write only
> > > 1
> > > byte, so I thought that introducing a call there (when compiling
> > > without KMSAN) would be unacceptable.

[...]

> > As stated above, I don't think this is more or less working as
> > intended.
> > If we really want the ability to inline __memset(), we could
> > transform
> > it into memset() in non-sanitizer builds, but perhaps having a call
> > is
> > also acceptable?
> 
> Thanks for the detailed explanation and analysis. I will post
> a version with a __memset() and let the slab maintainers decide if
> the additional overhead is acceptable.

I noticed I had the same problem in the get_user()/put_user() and
check_canary() patches.

The annotation being silently ignored is never what a programmer
intends, so what do you think about adding noinline to
__no_kmsan_checks and __no_sanitize_memory?