[Bug 99706] [BAT] [HSW] drv_hangman/error-state-basic failing frequently in CI

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=99706

--- Comment #5 from Chris Wilson <chris at chris-wilson.co.uk> ---
Probably:

Greetings,

0day kernel testing robot got the below dmesg and the first bad commit is

git://anongit.freedesktop.org/drm-intel topic/core-for-CI

commit 585774774191cce113cd3ab1419499d8a7f7687e
Author:     Peter Zijlstra <peterz at infradead.org>
AuthorDate: Wed Jan 11 17:43:02 2017 +0100
Commit:     Chris Wilson <chris at chris-wilson.co.uk>
CommitDate: Mon Feb 20 17:07:24 2017 +0000

    locking/mutex: Clear mutex-handoff flag on interrupt

    On Mon, Jan 09, 2017 at 11:52:03AM +0000, Chris Wilson wrote:
    > If we abort the mutex_lock() due to an interrupt, or other error from

    s/interrupt/signal/, right?

    > ww_mutex, we need to relinquish the handoff flag if we applied it.
    > Otherwise, we may cause missed wakeups as the current owner may try to
    > handoff to a new thread that is not expecting the handoff and so sleep
    > thinking the lock is already claimed (and since the owner unlocked there
    > may never be a new wakeup).

    Isn't that the exact same scenario as Nicolai fixed here:

     
http://lkml.kernel.org/r/1482346000-9927-3-git-send-email-nhaehnle@gmail.com

    Did you, like Nicolai, find this by inspection, or can you reproduce?

    FWIW, I have the below patch that should also solve this problem afaict.

d8870ff73d  mm/vmalloc: Replace opencoded 4-level page walkers
5857747741  locking/mutex: Clear mutex-handoff flag on interrupt

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