Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64

From	Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64
Date	2017-08-08 18:10 +0200
Message-ID	<ucfeY-2nP-71@gated-at.bofh.it> (permalink)
References	<ucaoX-7av-29@gated-at.bofh.it> <uceLW-1Xt-65@gated-at.bofh.it> <uceVz-21I-9@gated-at.bofh.it>
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On Tue, Aug 8, 2017 at 8:41 AM, Mark Rutland <mark.rutland@arm.com> wrote:
>
> With my __BUG_FLAGS() issue corrected, the WARN_ON_ONCE() fires once,
> and everything else seems fine. I'll have a go with additional debug
> enabled just in case.

Ok, great, a - mostly - false alarm.

I do wonder if we should just remove even that WARN_ON_ONCE() - I
think it was added to be careful, and the code seems to do the right
thing.

The second WARN_ON_ONCE() (that is marked as "should be impossible")
we might as well leave around. If that one triggers, it's a lot more
interesting.

Mel? No hurry - the nice thing about WARN_ON_ONCE() is that it's just
a single note so it's neither killing the machine(*) nor causing any
real problems.

                Linus

(*) when it works, but presumably it is now fixed on ARM64, and I
expect I'll see a pull request ;).

Thread

kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64 Mark Rutland <mark.rutland@arm.com> - 2017-08-08 13:00 +0200
  Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64 Mark Rutland <mark.rutland@arm.com> - 2017-08-08 17:00 +0200
    Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64 Mark Rutland <mark.rutland@arm.com> - 2017-08-08 17:20 +0200
  Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64 Mel Gorman <mgorman@suse.de> - 2017-08-08 17:40 +0200
    Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64 Mark Rutland <mark.rutland@arm.com> - 2017-08-08 17:50 +0200
      Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64 Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-08 18:10 +0200
        Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64 Mel Gorman <mgorman@suse.de> - 2017-08-08 18:50 +0200
          Re: kernel BUG at kernel/futex.c:679 on v4.13-rc3-ish on arm64 Mark Rutland <mark.rutland@arm.com> - 2017-08-08 19:10 +0200

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