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Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git] ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at 0000039c

From Thomas Gleixner <tglx@linutronix.de>
Newsgroups linux.kernel
Subject Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git] ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at 0000039c
Date 2017-02-27 18:10 +0100
Message-ID <tfwlt-86h-23@gated-at.bofh.it> (permalink)
References (3 earlier) <teOX7-3ef-1@gated-at.bofh.it> <tfqzo-491-7@gated-at.bofh.it> <tftdU-5Yo-23@gated-at.bofh.it> <tfvIJ-7An-7@gated-at.bofh.it> <tfw26-7YC-13@gated-at.bofh.it>
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On Mon, 27 Feb 2017, Tony Lindgren wrote:
> * Ingo Molnar <mingo@kernel.org> [170227 07:44]:
> > Because it's not the requirement that hurts primarily, but the resulting 
> > non-determinism and the sporadic crashes. Which can be solved by making the race 
> > deterministic via the debug facility.
> > 
> > If the IRQ handler crashed the moment it was first written by the driver author 
> > we'd never see these problems.
> 
> Just in case this is PM related.. Maybe the spurious interrupt is pending
> from earlier? This could be caused by glitches on the lines with runtime PM,
> or a pending interrupt during suspend/resume. In that case IRQ_DISABLE_UNLAZY
> might provide more clues if the problem goes away.

It's not PM related.  That's just silly hardware. At the moment when you
enable some magic bit in the control register, which is required to probe
the version, the fricking thing spits out a spurious interrupt despite the
interrupt enable bit in the same control register being still disabled. Of
course we cannot install an interrupt handler before having probed the
version and setup other stuff, except we add magic 'if (!initialized)'
crappola into the handler and lose the ability to install version dependent
handlers afterwards.

Wonderful crap that, isn't it?

Thanks,

	tglx

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Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at 0000039c Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-24 20:20 +0100
  Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Ingo Molnar <mingo@kernel.org> - 2017-02-25 10:10 +0100
    Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at 0000039c Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-25 19:10 +0100
      Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Thomas Gleixner <tglx@linutronix.de> - 2017-02-27 11:20 +0100
        Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Thomas Gleixner <tglx@linutronix.de> - 2017-02-27 14:10 +0100
          Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Ingo Molnar <mingo@kernel.org> - 2017-02-27 16:50 +0100
            Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Tony Lindgren <tony@atomide.com> - 2017-02-27 17:10 +0100
              Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Tony Lindgren <tony@atomide.com> - 2017-02-27 17:30 +0100
              Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Thomas Gleixner <tglx@linutronix.de> - 2017-02-27 18:10 +0100
            Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Thomas Gleixner <tglx@linutronix.de> - 2017-02-27 18:10 +0100
            Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at 0000039c Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-27 23:30 +0100
              Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Ingo Molnar <mingo@kernel.org> - 2017-02-28 11:30 +0100
              Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Thomas Gleixner <tglx@linutronix.de> - 2017-02-28 15:00 +0100
  Re: [WARNING: A/V UNSCANNABLE][Merge tag 'media/v4.11-1' of git]  ff58d005cd: BUG: unable to handle kernel NULL pointer dereference at  0000039c Sean Young <sean@mess.org> - 2017-02-25 12:20 +0100
    [PATCH] [media] serial_ir: ensure we're ready to receive interrupts Sean Young <sean@mess.org> - 2017-02-25 12:30 +0100
      Re: [PATCH] [media] serial_ir: ensure we're ready to receive  interrupts Mauro Carvalho Chehab <mchehab@infradead.org> - 2017-02-25 14:40 +0100
        Re: [PATCH] [media] serial_ir: ensure we're ready to receive  interrupts Mauro Carvalho Chehab <mchehab@infradead.org> - 2017-02-25 15:00 +0100

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