linux-kernel - Re: [PATCH] iommu/amd: Take mmap_sem when calling get_user

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Date:	Tue, 6 May 2014 14:27:08 -0500
From:	Suravee Suthikulanit <suravee.suthikulpanit@....com>
To:	Joerg Roedel <joro@...tes.org>
CC:	<iommu@...ts.linux-foundation.org>, <linux-kernel@...r.kernel.org>,
	<kim.naru@....com>, <jay.cornwall@....com>
Subject: Re: [PATCH] iommu/amd: Take mmap_sem when calling get_user_pages

On 5/6/2014 2:11 PM, Suravee Suthikulanit wrote:
> On 5/6/2014 1:14 PM, Joerg Roedel wrote:
>> On Mon, Apr 28, 2014 at 05:27:46PM -0500, Suthikulpanit, Suravee wrote:
>>> From: Jay Cornwall <jay.cornwall@....com>
>>>
>>> get_user_pages requires caller to hold a read lock on mmap_sem.
>>
>> Right, but can't we just switch to get_user_pages_fast instead?
>>
>>
>>     Joerg
>>
>
> You're right. I think it can. Let me spin out another patch.
>
> Suravee
>

Actually, we would have to provide the pointer to task_struct for the 
corresponding PASID which is not necessary "current".  So I take it 
back. I don't think we can use _fast.

Suravee
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