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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 11:20 +0100
Message-ID <tfqzo-491-7@gated-at.bofh.it> (permalink)
References <tesMV-41Q-1@gated-at.bofh.it> <tetzj-4CB-3@gated-at.bofh.it> <teGwy-5C9-5@gated-at.bofh.it> <teOX7-3ef-1@gated-at.bofh.it>
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On Sat, 25 Feb 2017, Linus Torvalds wrote:
> On Sat, Feb 25, 2017 at 1:07 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > So, should we revert the hw-retrigger change:
> >
> >   a9b4f08770b4 x86/ioapic: Restore IO-APIC irq_chip retrigger callback
> >
> > ... until we managed to fix CONFIG_DEBUG_SHIRQ=y? If you'd like to revert it
> > upstream straight away:
> >
> > Acked-by: Ingo Molnar <mingo@kernel.org>
> 
> So I'm in no huge hurry to revert that commit as long as we're still
> in the merge window or early -rc's.
> 
> From a debug standpoint, the spurious early interrupts are fine, and
> hopefully will help us find more broken drivers.
> 
> It's just that I'd like to revert it before the actual 4.11 release,
> unless we can find a better solution.
> 
> Because it really seems like the interrupt re-trigger is entirely
> bogus. It's not an _actual_ "re-trigger the interrupt that may have
> gotten lost", it's some code that ends up triggering it for no good
> reason.
> 
> So I'd actually hope that we could figure out why IRQS_PENDING got
> set, and perhaps fix the underlying cause?
>
> There are several things that set IRQS_PENDING, ranging from "try to
> test mis-routed interrupts while irqd was working", to "prepare for
> suspend losing the irq for us", to "irq auto-probing uses it on
> unassigned probable irqs".
> 
> The *actual* reason to re-send, namely getting a nested irq that we
> had to drop because we got a second one while still handling the first
> (or because it was disabled), is just one case.
> 
> Personally, I'd suspect some left-over state from auto-probing earlier
> in the boot, but I don't know. Could we fix that underlying issue?

I'm on 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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