ACK: [PATCH 1/1][Eoan][SRU Disco] dma-direct: fix zone selection after an unaddressable CMA allocation

[Kleber Souza]

On 8/27/19 3:26 AM, dann frazier wrote:
> From: Christoph Hellwig <hch at lst.de>
> 
> BugLink: https://bugs.launchpad.net/bugs/1841483
> 
> The new dma_alloc_contiguous hides if we allocate CMA or regular
> pages, and thus fails to retry a ZONE_NORMAL allocation if the CMA
> allocation succeeds but isn't addressable.  That means we either fail
> outright or dip into a small zone that might not succeed either.
> 
> Thanks to Hillf Danton for debugging this issue.
> 
> Fixes: b1d2dc009dec ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers")
> Reported-by: Tobias Klausmann <tobias.johannes.klausmann at mni.thm.de>
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> Tested-by: Tobias Klausmann <tobias.johannes.klausmann at mni.thm.de>
> (backported from commit 90ae409f9eb3bcaf38688f9ec22375816053a08e)
> [ dannf: dropped dma-iommu.c changes, as that didn't switch over to the
>   new dma_alloc_contiguous() interface until after v5.2 ]
> Signed-off-by: dann frazier <dann.frazier at canonical.com>

Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>

> ---
>  include/linux/dma-contiguous.h |  5 +----
>  kernel/dma/contiguous.c        |  8 ++------
>  kernel/dma/direct.c            | 10 +++++++++-
>  3 files changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h
> index c05d4e661489b..03f8e98e3bcc9 100644
> --- a/include/linux/dma-contiguous.h
> +++ b/include/linux/dma-contiguous.h
> @@ -160,10 +160,7 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages,
>  static inline struct page *dma_alloc_contiguous(struct device *dev, size_t size,
>  		gfp_t gfp)
>  {
> -	int node = dev ? dev_to_node(dev) : NUMA_NO_NODE;
> -	size_t align = get_order(PAGE_ALIGN(size));
> -
> -	return alloc_pages_node(node, gfp, align);
> +	return NULL;
>  }
>  
>  static inline void dma_free_contiguous(struct device *dev, struct page *page,
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index 2bd410f934b32..69cfb4345388c 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -230,9 +230,7 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages,
>   */
>  struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
>  {
> -	int node = dev ? dev_to_node(dev) : NUMA_NO_NODE;
> -	size_t count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> -	size_t align = get_order(PAGE_ALIGN(size));
> +	size_t count = size >> PAGE_SHIFT;
>  	struct page *page = NULL;
>  	struct cma *cma = NULL;
>  
> @@ -243,14 +241,12 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
>  
>  	/* CMA can be used only in the context which permits sleeping */
>  	if (cma && gfpflags_allow_blocking(gfp)) {
> +		size_t align = get_order(size);
>  		size_t cma_align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT);
>  
>  		page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN);
>  	}
>  
> -	/* Fallback allocation of normal pages */
> -	if (!page)
> -		page = alloc_pages_node(node, gfp, align);
>  	return page;
>  }
>  
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 0816c1e8b05af..18596b804d384 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -96,6 +96,8 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
>  struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
>  		dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
>  {
> +	size_t alloc_size = PAGE_ALIGN(size);
> +	int node = dev_to_node(dev);
>  	struct page *page = NULL;
>  	u64 phys_mask;
>  
> @@ -106,8 +108,14 @@ struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
>  	gfp &= ~__GFP_ZERO;
>  	gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
>  			&phys_mask);
> +	page = dma_alloc_contiguous(dev, alloc_size, gfp);
> +	if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
> +		dma_free_contiguous(dev, page, alloc_size);
> +		page = NULL;
> +	}
>  again:
> -	page = dma_alloc_contiguous(dev, size, gfp);
> +	if (!page)
> +		page = alloc_pages_node(node, gfp, get_order(alloc_size));
>  	if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
>  		dma_free_contiguous(dev, page, size);
>  		page = NULL;
>