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Subject: Re: regression in ath10k dma allocation
To:     Christoph Hellwig <hch@lst.de>, Hillf Danton <hdanton@sina.com>
Cc:     Nicolin Chen <nicoleotsuka@gmail.com>, kvalo@codeaurora.org,
        davem@davemloft.net, ath10k@lists.infradead.org,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, m.szyprowski@samsung.com,
        robin.murphy@arm.com, iommu@lists.linux-foundation.org,
        tobias.klausmann@freenet.de
References: <8fe8b415-2d34-0a14-170b-dcb31c162e67@mni.thm.de>
 <20190816164301.GA3629@lst.de>
 <af96ea6a-2b17-9b66-7aba-b7dae5bcbba5@mni.thm.de>
 <20190816222506.GA24413@Asurada-Nvidia.nvidia.com>
 <20190818031328.11848-1-hdanton@sina.com>
 <acd7a4b0-fde8-1aa2-af07-2b469e5d5ca7@mni.thm.de>
 <20190820065833.1628-1-hdanton@sina.com> <20190820071250.GA28968@lst.de>
From:   Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
Message-ID: <c11b5c86-3c10-35f6-b07e-e090d42d97ed@mni.thm.de>
Date:   Tue, 20 Aug 2019 22:24:29 +0200
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On 20.08.19 09:12, Christoph Hellwig wrote:
> On Tue, Aug 20, 2019 at 02:58:33PM +0800, Hillf Danton wrote:
>> On Tue, 20 Aug 2019 05:05:14 +0200 Christoph Hellwig wrote:
>>> Tobias, plase try this patch:
>>>
> New version below:
>
> ---
>  From b8a805e93be5a5662323b8ac61fe686df839c4ac Mon Sep 17 00:00:00 2001
> From: Christoph Hellwig <hch@lst.de>
> Date: Tue, 20 Aug 2019 11:45:49 +0900
> Subject: dma-direct: fix zone selection after an unaddressable CMA allocation
>
> 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@mni.thm.de>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/iommu/dma-iommu.c      |  3 +++
>   include/linux/dma-contiguous.h |  5 +----
>   kernel/dma/contiguous.c        |  9 +++------
>   kernel/dma/direct.c            | 10 +++++++++-
>   4 files changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index d991d40f797f..f68a62c3c32b 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -965,10 +965,13 @@ static void *iommu_dma_alloc_pages(struct device *dev, size_t size,
>   {
>   	bool coherent = dev_is_dma_coherent(dev);
>   	size_t alloc_size = PAGE_ALIGN(size);
> +	int node = dev_to_node(dev);
>   	struct page *page = NULL;
>   	void *cpu_addr;
>   
>   	page = dma_alloc_contiguous(dev, alloc_size, gfp);
> +	if (!page)
> +		page = alloc_pages_node(node, gfp, get_order(alloc_size));
>   	if (!page)
>   		return NULL;
>   
> diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h
> index c05d4e661489..03f8e98e3bcc 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 2bd410f934b3..e6b450fdbeb6 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;
>   }
>   
> @@ -258,6 +254,7 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
>    * dma_free_contiguous() - release allocated pages
>    * @dev:   Pointer to device for which the pages were allocated.
>    * @page:  Pointer to the allocated pages.
> +	int node = dev ? dev_to_node(dev) : NUMA_NO_NODE;
>    * @size:  Size of allocated pages.
>    *
>    * This function releases memory allocated by dma_alloc_contiguous(). As the
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 795c9b095d75..706113c6bebc 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -85,6 +85,8 @@ 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;
>   
> @@ -95,8 +97,14 @@ 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;

I can confirm this resolves the regression!

Tested-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>


Thanks for the work of all involved,

Tobias