Re: [PATCH v2 1/2] rtmutex Real-Time Linux: Fixing kernel BUG at kernel/locking/rtmutex.c:997!

From: Mike Galbraith
Date: Tue Apr 07 2015 - 07:47:26 EST


On Tue, 2015-04-07 at 13:23 +0200, Thomas Gleixner wrote:
> On Mon, 6 Apr 2015, Thavatchai Makphaibulchoke wrote:
>
> > This patch fixes the problem that the ownership of a mutex acquired
> > by an interrupt handler(IH) gets incorrectly attributed to the
> > interrupted thread.
>
> An hard interrupt handler is not allowed to take a mutex. End of
> story, nothing to fix here.

Well, the patch that started this thread..

timers-do-not-raise-softirq-unconditionally.patch

..(attributed to you) was picked up in -rt (perhaps erroneously) to
get nohz_full working, and then reverted due to the deadlock detector
getting properly angry. All of this is about reinstating it.

I posted a patchlet to simply subtract softirqd from the ->nr_running
check, which gets nohz_full working in -rt sans illegal activity.

-Mike
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