linux-kernel - Re: [PATCH 9/9] ttm/dma: Implement set_page_caching implementation in the TTM DMA pool code.

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Message-ID: <20110929224507.GA32650@phenom.oracle.com>
Date:	Thu, 29 Sep 2011 18:45:07 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Kevin Shanahan <kmshanah@...enchant.net>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 9/9] ttm/dma: Implement set_page_caching implementation
 in the TTM DMA pool code.

On Fri, Sep 30, 2011 at 07:46:15AM +0930, Kevin Shanahan wrote:
> On 2011-09-29 20:33:52, Konrad Rzeszutek Wilk wrote:
> > . which is pretty much like the other TTM pool except it
> > also handles moving the page to another pool list.
> > 
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> > ---
> >  drivers/gpu/drm/ttm/ttm_page_alloc_dma.c |   96 ++++++++++++++++++++++++++++++
> >  1 files changed, 96 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> > index 5909d28..cea031e 100644
> > --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> > +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> > @@ -1307,11 +1307,107 @@ static int ttm_dma_page_alloc_debugfs(struct seq_file *m, void *data)
> >  	mutex_unlock(&_manager->lock);
> >  	return 0;
> >  }
> > +#ifdef CONFIG_X86
> > +static int ttm_dma_page_set_page_caching(struct page *p,
> > +					 int flags,
> > +					 enum ttm_caching_state c_old,
> > +					 enum ttm_caching_state c_new,
> > +					 struct device *dev)
> > +{
> > +	struct dma_pool *src, *dst;
> > +	enum pool_type type;
> > +	struct dma_page *dma_p;
> > +	bool found = false;
> > +	unsigned long irq_flags;
> > +	int ret = 0;
> > +
> > +	if (!p)
> > +		return 0;
> > +
> > +	if (PageHighMem(p))
> > +		return 0;
> > +
> > +	type = ttm_to_type(flags, c_old);
> > +	src = ttm_dma_find_pool(dev, type);
> > +	if (!src) {
> > +		WARN_ON(!src);
> > +		return -ENOMEM;
> > +	}
> > +	type = ttm_to_type(flags, c_new);
> > +	dst = ttm_dma_find_pool(dev, type);
> > +	if (!dst) {
> > +		gfp_t gfp_flags;
> > +		if (flags & TTM_PAGE_FLAG_DMA32)
> > +			gfp_flags = GFP_USER | GFP_DMA32;
> > +		else
> > +			gfp_flags = GFP_HIGHUSER;
> > +
> > +		if (flags & TTM_PAGE_FLAG_ZERO_ALLOC)
> > +			gfp_flags |= __GFP_ZERO;
> > +
> > +		dst = ttm_dma_pool_init(dev, gfp_flags, type);
> > +		if (IS_ERR_OR_NULL(dst))
> > +			return -ENOMEM;
> > +	}
> > +
> > +	dev_dbg(dev, "(%d) Caching %p (%p) from %x to %x.\n", current->pid,
> > +		p, page_address(p), c_old, c_new);
> > +
> > +	if (c_old != tt_cached) {
> > +		/* p isn't in the default caching state, set it to
> > +		 * writeback first to free its current memtype. */
> > +
> > +		ret = set_pages_wb(p, 1);
> > +		if (ret)
> > +			return ret;
> > +	}
> >  
> > +	if (c_new == tt_wc)
> > +		ret = set_memory_wc((unsigned long) page_address(p), 1);
> > +	else if (c_new == tt_uncached)
> > +		ret = set_pages_uc(p, 1);
> > +
> > +	if (ret)
> > +		return ret;
> > +
> > +	dev_dbg(src->dev, "(%s:%d) Moving %p (%p) to %s.\n", src->name,
> > +		current->pid, p, page_address(p), dst->name);
> > +
> > +	/* To make it faster we only take the spinlock on list
> > +	 * removal, and later on adding the page to the destination pool. */
> > +	spin_lock_irqsave(&src->lock, irq_flags);
> > +	list_for_each_entry(dma_p, &src->page_list, page_list) {
> > +		if (virt_to_page(dma_p->vaddr) != p) {
> > +			pr_debug("%s: (%s:%d) Skipping %p (%p) (DMA:0x%lx)\n",
> > +				src->dev_name, src->name, current->pid,
> > +				dma_p->vaddr,
> > +				virt_to_page(dma_p->vaddr),
> > +				(unsigned long)dma_p->dma);
> > +			continue;
> > +		}
> > +		list_del(&dma_p->page_list);
> > +		src->npages_in_use -= 1;
> > +		found = true;
> > +		break;
> > +	}
> > +	spin_lock_irqsave(&src->lock, irq_flags);
>         ^^^^^^^^^^^^^^^^^
> 
> Was this meant to be spin_unlock_irqrestore?

Yup! Fixing it up. Hmm.... how did it run. This is called from the TTM shrinker
when the memory pressure is low, unless I am reading the code wrong.
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