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

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Date:   Thu, 14 Nov 2019 22:33:03 +0100
From:   Marco Elver <elver@...gle.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     akiyks@...il.com, stern@...land.harvard.edu, glider@...gle.com,
        parri.andrea@...il.com, andreyknvl@...gle.com, luto@...nel.org,
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        j.alglave@....ac.uk, joel@...lfernandes.org, corbet@....net,
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Subject: Re: [PATCH v4 00/10] Add Kernel Concurrency Sanitizer (KCSAN)

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@mail.gmail.com
> > 
> > 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.

Thanks,
-- Marco