linux-kernel - Re: [PATCH v3] [SCSI] mpt2sas, mpt3sas: Abort initialization if no memory I/O resources detected

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Message-ID: <55A6AA89.60202@raptorengineeringinc.com>
Date:	Wed, 15 Jul 2015 13:46:33 -0500
From:	Timothy Pearson <tpearson@...torengineeringinc.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Sreekanth Reddy <sreekanth.reddy@...gotech.com>,
	James Bottomley <jejb@...nel.org>, martin.petersen@...cle.com,
	Linux-Scsi <linux-scsi@...r.kernel.org>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	Sathya.Prakash@...gotech.com,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Christoph Hellwig <hch@...radead.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
Subject: Re: [PATCH v3] [SCSI] mpt2sas, mpt3sas: Abort initialization if no
 memory I/O resources detected

On 07/15/2015 01:28 PM, Yinghai Lu wrote:
> On Wed, Jul 15, 2015 at 6:52 AM, Timothy Pearson
> <tpearson@...torengineeringinc.com> wrote:
>>> I have just kept the same description provide by Timothy in his
>>> initial patch.
>>>
>>> But I observe that their may be chance of getting "unable to handle
>>> kernel NULL pointer dereference" kernel panic if no Memory Resource
>>> available in the PCI subsystem. So agreed to the Timothy proposal of
>>> aborting the driver initialization if it doesn't detect any Memory
>>> resource instead of whole system get into panic state.
>>>
>> On some systems Linux is unable / unwilling to assign a BAR if the BIOS
>> does not assign one at startup.  I didn't look into the Linux allocator
>> side of things in much detail, but it is quite possible that Linux is
>> unaware the device only has partial resources assigned.
>>
> 
> Would be great if you can post boot log so we can figure about why those
> BARs are not assigned.
> 
> Yinghai

Unfortunately the systems exhibiting the issue were upgraded to a later
BIOS that does not have this problem; it might be possible to set up a
test system in the future but that probably won't happen for some time.

-- 
Timothy Pearson
Raptor Engineering
+1 (415) 727-8645
http://www.raptorengineeringinc.com
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