linux-kernel - Re: [PATCH] staging: zsmalloc: Ensure handle is never 0 on success

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Date:	Wed, 06 Nov 2013 16:00:02 -0800
From:	Olav Haugan <ohaugan@...eaurora.org>
To:	Greg KH <gregkh@...uxfoundation.org>
CC:	ngupta@...are.org, sjenning@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org, minchan@...nel.org,
	linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] staging: zsmalloc: Ensure handle is never 0 on success

On 11/5/2013 5:56 PM, Greg KH wrote:
> On Tue, Nov 05, 2013 at 04:54:12PM -0800, Olav Haugan wrote:
>> zsmalloc encodes a handle using the page pfn and an object
>> index. On some hardware platforms the pfn could be 0 and this
>> causes the encoded handle to be 0 which is interpreted as an
>> allocation failure.
> 
> What platforms specifically have this issue?

Currently some of Qualcomm SoC's have physical memory that starts at
address 0x0 which causes this problem. I believe this could be a problem
on any platforms if memory is configured to be starting at physical
address 0x0 for these platforms.

>>
>> To prevent this false error we ensure that the encoded handle
>> will not be 0 when allocation succeeds.
>>
>> Change-Id: Ifff930dcf254915b497aec5cb36f152a5e5365d6
> 
> What is this?  What can anyone do with it?

This is an identifier used by "Gerrit Code Review" to track changes to
the same patch. I will remove it.

Olav Haugan

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