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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Wed, 23 Jun 2021 16:39:11 -0700
Message-ID: <CAKwvOd=Y1fhJM7NpotvjNy3OE+JtqEBy046ctwE=cqV_ge5tgw@mail.gmail.com>
Subject: Re: Build failure in -next
To:     "Paul E. McKenney" <paulmck@kernel.org>
Cc:     aneesh.kumar@linux.ibm.com, LKML <linux-kernel@vger.kernel.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Marco Elver <elver@google.com>,
        clang-built-linux <clang-built-linux@googlegroups.com>
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On Wed, Jun 23, 2021 at 3:30 PM Paul E. McKenney <paulmck@kernel.org> wrote:
>
> Hello, Aneesh!
>
> Yesterday evening's next-20210622 testing gave me the following
> kernel-build error:
>
> ld: mm/mremap.o: in function `move_huge_pud':
> /home/git/linux-next/mm/mremap.c:372: undefined reference to `__compiletime_assert_395'
>
> Bisection landed on this commit:
>
> 257121c5aabe ("mm/mremap: convert huge PUD move to separate helper")
>
> I have no idea how this commit relates to that error message, but
> reverting this commit on top of next-20210622 really does get rid of
> the problem.
>
> The following reproducer provokes this error:
>
> tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --torture lock --configs LOCK07 --build-only --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --kmake-arg "CC=clang-11"
>
> Run the above command in the top-level directory of your -next source
> tree, and using this compiler:
>
> $ clang-11 -v
> Ubuntu clang version 11.1.0-++20210428103817+1fdec59bffc1-1~exp1~20210428204431.166
> Target: x86_64-pc-linux-gnu
>
> Thoughts?
>
>                                                         Thanx, Paul

++beers_owed; for the report and bisection. Also reported
https://lore.kernel.org/lkml/YM0mrZIPM+sWTDHf@Ryzen-9-3900X.localdomain/,
let's chat over there.

-- 
Thanks,
~Nick Desaulniers