linux-kernel - Re: [PATCH] drm/ttm: dma: Don't crash on memory in the vmalloc range

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Date:	Tue, 19 May 2015 20:33:59 +0900
From:	Alexandre Courbot <acourbot@...dia.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Thierry Reding <thierry.reding@...il.com>,
	David Airlie <airlied@...ux.ie>
CC:	Thomas Hellstrom <thellstrom@...are.com>,
	Arnd Bergmann <arnd@...db.de>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
	<gnurou@...il.com>
Subject: Re: [PATCH] drm/ttm: dma: Don't crash on memory in the vmalloc range

On 05/16/2015 04:55 AM, Konrad Rzeszutek Wilk wrote:
> On Fri, May 15, 2015 at 04:09:54PM +0900, Alexandre Courbot wrote:
>> dma_alloc_coherent() can return memory in the vmalloc range.
>> virt_to_page() cannot handle such addresses and crashes. This
>> patch detects such cases and obtains the struct page * using
>> vmalloc_to_page() instead.
>>
>> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
>> ---
>> This patch is a follow-up of the following discussion:
>>
>> https://www.marc.info/?l=dri-devel&m=141579595431254&w=3
>>
>> It works for me on both 32-bit and 64-bit Tegra, so I am not convinced
>> that Thierry's initial change from virt_to_page() to phys_to_page() is
>> still required - Thierry, can you confirm whether your patch is still
>> relevant after this one?
>>
>>   drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 9 ++++++---
>>   1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
>> index 01e1d27eb078..3077f1554099 100644
>> --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
>> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
>> @@ -342,9 +342,12 @@ static struct dma_page *__ttm_dma_alloc_page(struct dma_pool *pool)
>>   	d_page->vaddr = dma_alloc_coherent(pool->dev, pool->size,
>>   					   &d_page->dma,
>>   					   pool->gfp_flags);
>> -	if (d_page->vaddr)
>> -		d_page->p = virt_to_page(d_page->vaddr);
>> -	else {
>> +	if (d_page->vaddr) {
>> +		if (is_vmalloc_addr(d_page->vaddr))
>> +			d_page->p = vmalloc_to_page(d_page->vaddr);
>> +		else
>> +			d_page->p = virt_to_page(d_page->vaddr);
>> +	} else {
>
>
> Looks OK to me.

Thanks guys. Could we translate these approvals into 
Acked-bys/Reviewed-bys so Dave (?) can merge this patch?
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