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Groups > linux.kernel > #1623708
| From | Tony Lindgren <tony@atomide.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] futex: Fix hrtimer oops in futex_lock_pi() |
| Date | 2017-04-14 16:50 +0200 |
| Message-ID | <twaHT-2g9-11@gated-at.bofh.it> (permalink) |
| References | <twa5c-22B-13@gated-at.bofh.it> <twaoy-29o-21@gated-at.bofh.it> <twaoy-29o-19@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
* Tony Lindgren <tony@atomide.com> [170414 07:28]:
> * Peter Zijlstra <peterz@infradead.org> [170414 07:25]:
> > On Fri, Apr 14, 2017 at 07:08:19AM -0700, Tony Lindgren wrote:
> > > Commit cfafcd117da0 ("futex: Rework futex_lock_pi() to use
> > > rt_mutex_*_proxy_lock()") caused a regression where things would
> > > occasionally randomly oops when restarting X:
> > >
> > > Unable to handle kernel NULL pointer dereference at virtual address 00000000
> > > ...
> > > Internal error: Oops: 80000005 [#1] SMP ARM
> > > ...
> > > PC is at 0x0
> > > LR is at __hrtimer_run_queues+0x138/0x58c
> > > pc : [<00000000>] lr : [<c01c7884>] psr: 20000193
> > > ...
> > > [<c01c7884>] (__hrtimer_run_queues) from [<c01c7f4c>]
> > > (hrtimer_interrupt+0xbc/0x210)
> > > [<c01c7f4c>] (hrtimer_interrupt) from [<c010fcfc>]
> > > ...
> > >
> > > When this happens, the hrtimer is not properly initialized and it's
> > > function is NULL. This happens because we now call hrtimer_start_expires()
> > > in futex_lock_pi() for the timer initialized with hrtimer_init_on_stack().
> > >
> > > To fix it, let's pair the hrtimer_start_expires() with hrtimer_cancel()
> > > in the same function.
> >
> > Already fixed:
> >
> > https://lkml.kernel.org/r/tip-97181f9bd57405b879403763284537e27d46963d@git.kernel.org
> >
> > Thanks for the patch though.
>
> Oh OK thanks. It seems to be missing in Linux next though.
Oh it was just committed, I see it now in tip after git fetch.
So should be heading into nex soon.
Tony
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[PATCH] futex: Fix hrtimer oops in futex_lock_pi() Tony Lindgren <tony@atomide.com> - 2017-04-14 16:10 +0200
Re: [PATCH] futex: Fix hrtimer oops in futex_lock_pi() Tony Lindgren <tony@atomide.com> - 2017-04-14 16:30 +0200
Re: [PATCH] futex: Fix hrtimer oops in futex_lock_pi() Tony Lindgren <tony@atomide.com> - 2017-04-14 16:50 +0200
Re: [PATCH] futex: Fix hrtimer oops in futex_lock_pi() Peter Zijlstra <peterz@infradead.org> - 2017-04-14 16:30 +0200
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