From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751882AbdB0KNh (ORCPT ); Mon, 27 Feb 2017 05:13:37 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:57814 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751763AbdB0KNd (ORCPT ); Mon, 27 Feb 2017 05:13:33 -0500 Date: Mon, 27 Feb 2017 11:09:41 +0100 (CET) From: Thomas Gleixner To: Linus Torvalds cc: Ingo Molnar , kernel test robot , Mauro Carvalho Chehab , Sean Young , Ruslan Ruslichenko , LKP , "linux-input@vger.kernel.org" , "linux-omap@vger.kernel.org" , kernel@stlinux.com, Linux Media Mailing List , linux-mediatek@lists.infradead.org, linux-amlogic@lists.infradead.org, "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" , Linux LED Subsystem , LKML , wfg@linux.intel.com 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 In-Reply-To: Message-ID: References: <58b07b30.9XFLj9Hhl7F6HMc2%fengguang.wu@intel.com> <20170225090741.GA20463@gmail.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@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