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Date:   Thu, 7 Jun 2018 22:11:02 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Josh Poimboeuf <jpoimboe@redhat.com>,
        Matthias Kaehlcke <mka@chromium.org>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        James Y Knight <jyknight@google.com>,
        Chandler Carruth <chandlerc@google.com>,
        Stephen Hines <srhines@google.com>,
        Kees Cook <keescook@google.com>, groeck@chromium.org,
        Greg Hackmann <ghackmann@google.com>
Subject: Re: [GIT PULL] x86/build changes for v4.17
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On Thu, Jun 07, 2018 at 12:23:31PM -0700, Nick Desaulniers wrote:
> On Wed, Apr 4, 2018 at 12:32 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> >
> > On Wed, Apr 04, 2018 at 04:53:52PM +0000, Nick Desaulniers wrote:
> > > (re-sending as plain text)
> > >
> > > On Wed, Apr 4, 2018 at 2:38 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > > > There are known-bugs with building a kernel with clang right now (I
> > > > pointed one out a few days ago about NULL checks being deleted from the
> > > > clang output for no good reason, which really is scary for obvious
> > > > reasons).
> > >
> > > Is this the thread you are referring to?
> > > https://lkml.org/lkml/2018/3/27/1286
> > >
> > > It's definitely something curious that I'll need to sit down and
> > > investigate more.  If there are other known instances, it would be good to
> > > let me know.
> >
> > As Matthias mentioned elsewhere, it sounds like they're planning to
> > implement -fno-delete-null-pointer-checks, which would presumably fix
> > the above issue.
> 
> Just to follow this up, -fno-delete-null-pointer-checks is being added
> to clang in:
> https://reviews.llvm.org/D47894
> https://reviews.llvm.org/D47895

That's great news, thanks for letting us know.

greg k-h