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

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Message-ID: <20150601172815.GC13347@x230>
Date:	Mon, 1 Jun 2015 13:28:15 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Alexandre Courbot <acourbot@...dia.com>
Cc:	Thierry Reding <thierry.reding@...il.com>,
	David Airlie <airlied@...ux.ie>,
	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 Tue, May 19, 2015 at 08:33:59PM +0900, Alexandre Courbot wrote:
> 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?

Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

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