Re: [PATCH v4 00/10] Add Kernel Concurrency Sanitizer (KCSAN)

[Paul E. McKenney]

On Thu, Nov 14, 2019 at 10:33:03PM +0100, Marco Elver wrote:
> On Thu, 14 Nov 2019, Paul E. McKenney wrote:
> 
> > On Thu, Nov 14, 2019 at 07:02:53PM +0100, Marco Elver wrote:
> > > This is the patch-series for the Kernel Concurrency Sanitizer (KCSAN).
> > > KCSAN is a sampling watchpoint-based *data race detector*. More details
> > > are included in **Documentation/dev-tools/kcsan.rst**. This patch-series
> > > only enables KCSAN for x86, but we expect adding support for other
> > > architectures is relatively straightforward (we are aware of
> > > experimental ARM64 and POWER support).
> > > 
> > > To gather early feedback, we announced KCSAN back in September, and have
> > > integrated the feedback where possible:
> > > http://lkml.kernel.org/r/CANpmjNPJ_bHjfLZCAPV23AXFfiPiyXXqqu72n6TgWzb2Gnu1eA@xxxxxxxxxxxxxx
> > > 
> > > The current list of known upstream fixes for data races found by KCSAN
> > > can be found here:
> > > https://github.com/google/ktsan/wiki/KCSAN#upstream-fixes-of-data-races-found-by-kcsan
> > > 
> > > We want to point out and acknowledge the work surrounding the LKMM,
> > > including several articles that motivate why data races are dangerous
> > > [1, 2], justifying a data race detector such as KCSAN.
> > > 
> > > [1] https://lwn.net/Articles/793253/
> > > [2] https://lwn.net/Articles/799218/
> > 
> > I queued this and ran a quick rcutorture on it, which completed
> > successfully with quite a few reports.
> 
> Great. Many thanks for queuing this in -rcu. And regarding merge window
> you mentioned, we're fine with your assumption to targeting the next
> (v5.6) merge window.
> 
> I've just had a look at linux-next to check what a future rebase
> requires:
> 
> - There is a change in lib/Kconfig.debug and moving KCSAN to the
>   "Generic Kernel Debugging Instruments" section seems appropriate.
> - bitops-instrumented.h was removed and split into 3 files, and needs
>   re-inserting the instrumentation into the right places.
> 
> Otherwise there are no issues. Let me know what you recommend.

Sounds good!

I will be rebasing onto v5.5-rc1 shortly after it comes out.  My usual
approach is to fix any conflicts during that rebasing operation.
Does that make sense, or would you prefer to send me a rebased stack at
that point?  Either way is fine for me.

							Thanx, Paul