linux-kernel - Re: WARNING: CPU: 4 PID: 863 at include/drm/drm_crtc.h:1577 drm_helper_choose_encoder_dpms+0x88/0x90()

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Date:	Wed, 30 Sep 2015 15:45:39 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Daniel Vetter <daniel@...ll.ch>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Alex Deucher <alexdeucher@...il.com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	Maling list - DRI developers 
	<dri-devel@...ts.freedesktop.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: WARNING: CPU: 4 PID: 863 at include/drm/drm_crtc.h:1577
 drm_helper_choose_encoder_dpms+0x88/0x90() - evildoer found and neutralized

n 2015/9/29 18:51, Borislav Petkov wrote:
> On Tue, Sep 29, 2015 at 04:50:36PM +0800, Jiang Liu wrote:
>> So could you please help to apply the attached debug patch to gather
>> more information about the regression?
> 
> Sure, just did.
> 
> I'm sending you a full s/r cycle attempt caught over serial in a private
> message.

Hi Boris,
>From the log file, we got to know that the NULL pointer dereference
was caused by AMD IOMMU device. For normal MSI-enabled PCI devices, we get
valid irq numbers such as:
[ 74.661170] ahci 0000:04:00.0: irqdomain: freeze msi 1 irq28
[ 74.661297] radeon 0000:01:00.0: irqdomain: freeze msi 1 irq47
But for AMD IOMMU device, we got an invalid irq number(0) after
enabling MSI as:
[ 74.662488] pci 0000:00:00.2: irqdomain: freeze msi 1 irq0
which then caused NULL pointer deference when __pci_restore_msi_state()
gets called by system resume code.
So we need to figure out why we got irq number 0 after enabling
MSI for AMD IOMMU device. The only hint I got is that iommu driver just
grabbing the PCI device without providing a PCI device driver for IOMMU
PCI device, we have solved a similar case for eata driver. So could you
please help to apply this debug patch to gather more info and send me
/proc/interrupts?
Thanks!
Gerry

O>
> Thanks.
> 

View attachment "0001-Debug-Gather-more-information-about-AMD-iommu-device.patch" of type "text/x-patch" (4546 bytes)