From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner 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: Mon, 27 Feb 2017 11:09:41 +0100 (CET) Message-ID: References: <58b07b30.9XFLj9Hhl7F6HMc2%fengguang.wu@intel.com> <20170225090741.GA20463@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+glpam-linux-mediatek=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: Linus Torvalds Cc: "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Ruslan Ruslichenko , "linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , kernel-F5mvAk5X5gdBDgjK7y7TUQ@public.gmane.org, Sean Young , wfg-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, LKML , Mauro Carvalho Chehab , linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Linux LED Subsystem , "linux-input-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , linux-amlogic-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, kernel test robot , LKP , Ingo Molnar , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , Linux Media Mailing List List-Id: linux-input@vger.kernel.org On Sat, 25 Feb 2017, Linus Torvalds wrote: > On Sat, Feb 25, 2017 at 1:07 AM, Ingo Molnar 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 > > 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