Re: [PATCH net-next v6] page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA

[Guillaume Tucker <guillaume.tucker@collabora.com>]

Hi Yunsheng,

Please see the bisection report below about a boot failure on
rk3288-rock2-square which is pointing to this patch.  The issue
appears to only happen with CONFIG_ARM_LPAE=y.

Reports aren't automatically sent to the public while we're
trialing new bisection features on kernelci.org but this one
looks valid.

Some more details can be found here:

  https://linux.kernelci.org/test/case/id/6189968c3ec0a3c06e3358fe/

Here's the same revision on the same platform booting fine with a
plain multi_v7_defconfig build:

  https://linux.kernelci.org/test/plan/id/61899d322c0e9fee7e3358ec/

Please let us know if you need any help debugging this issue or
if you have a fix to try.

Best wishes,
Guillaume


GitHub: https://github.com/kernelci/kernelci-project/issues/71

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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* This automated bisection report was sent to you on the basis  *
* that you may be involved with the breaking commit it has      *
* found.  No manual investigation has been done to verify it,   *
* and the root cause of the problem may be somewhere else.      *
*                                                               *
* If you do send a fix, please include this trailer:            *
*   Reported-by: "kernelci.org bot" <bot@kernelci.org>          *
*                                                               *
* Hope this helps!                                              *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

mainline/master bisection: baseline.login on rk3288-rock2-square

Summary:
  Start:      e851dfae4371d Merge tag 'kgdb-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux
  Plain log:  https://storage.kernelci.org/mainline/master/v5.15-11387-ge851dfae4371/arm/multi_v7_defconfig+CONFIG_EFI=y+CONFIG_ARM_LPAE=y/gcc-10/lab-collabora/baseline-rk3288-rock2-square.txt
  HTML log:   https://storage.kernelci.org/mainline/master/v5.15-11387-ge851dfae4371/arm/multi_v7_defconfig+CONFIG_EFI=y+CONFIG_ARM_LPAE=y/gcc-10/lab-collabora/baseline-rk3288-rock2-square.html
  Result:     d00e60ee54b12 page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA

Checks:
  revert:     PASS
  verify:     PASS

Parameters:
  Tree:       mainline
  URL:        https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
  Branch:     master
  Target:     rk3288-rock2-square
  CPU arch:   arm
  Lab:        lab-collabora
  Compiler:   gcc-10
  Config:     multi_v7_defconfig+CONFIG_EFI=y+CONFIG_ARM_LPAE=y
  Test case:  baseline.login

Breaking commit found:

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commit d00e60ee54b12de945b8493cf18c1ada9e422514
Author: Yunsheng Lin <linyunsheng@huawei.com>
Date:   Wed Oct 13 17:19:20 2021 +0800

    page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA
    

On 13/10/2021 10:19, Yunsheng Lin wrote:
> As the 32-bit arch with 64-bit DMA seems to rare those days,
> and page pool might carry a lot of code and complexity for
> systems that possibly.
> 
> So disable dma mapping support for such systems, if drivers
> really want to work on such systems, they have to implement
> their own DMA-mapping fallback tracking outside page_pool.
> 
> Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
> ---
> V6: Drop pp page tracking support
> ---
>  include/linux/mm_types.h | 13 +------------
>  include/net/page_pool.h  | 12 +-----------
>  net/core/page_pool.c     | 10 ++++++----
>  3 files changed, 8 insertions(+), 27 deletions(-)
> 
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 7f8ee09c711f..436e0946d691 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -104,18 +104,7 @@ struct page {
>  			struct page_pool *pp;
>  			unsigned long _pp_mapping_pad;
>  			unsigned long dma_addr;
> -			union {
> -				/**
> -				 * dma_addr_upper: might require a 64-bit
> -				 * value on 32-bit architectures.
> -				 */
> -				unsigned long dma_addr_upper;
> -				/**
> -				 * For frag page support, not supported in
> -				 * 32-bit architectures with 64-bit DMA.
> -				 */
> -				atomic_long_t pp_frag_count;
> -			};
> +			atomic_long_t pp_frag_count;
>  		};
>  		struct {	/* slab, slob and slub */
>  			union {
> diff --git a/include/net/page_pool.h b/include/net/page_pool.h
> index a4082406a003..3855f069627f 100644
> --- a/include/net/page_pool.h
> +++ b/include/net/page_pool.h
> @@ -216,24 +216,14 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
>  	page_pool_put_full_page(pool, page, true);
>  }
>  
> -#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT	\
> -		(sizeof(dma_addr_t) > sizeof(unsigned long))
> -
>  static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
>  {
> -	dma_addr_t ret = page->dma_addr;
> -
> -	if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
> -		ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16;
> -
> -	return ret;
> +	return page->dma_addr;
>  }
>  
>  static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
>  {
>  	page->dma_addr = addr;
> -	if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
> -		page->dma_addr_upper = upper_32_bits(addr);
>  }
>  
>  static inline void page_pool_set_frag_count(struct page *page, long nr)
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 1a6978427d6c..9b60e4301a44 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -49,6 +49,12 @@ static int page_pool_init(struct page_pool *pool,
>  	 * which is the XDP_TX use-case.
>  	 */
>  	if (pool->p.flags & PP_FLAG_DMA_MAP) {
> +		/* DMA-mapping is not supported on 32-bit systems with
> +		 * 64-bit DMA mapping.
> +		 */
> +		if (sizeof(dma_addr_t) > sizeof(unsigned long))
> +			return -EOPNOTSUPP;
> +
>  		if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
>  		    (pool->p.dma_dir != DMA_BIDIRECTIONAL))
>  			return -EINVAL;
> @@ -69,10 +75,6 @@ static int page_pool_init(struct page_pool *pool,
>  		 */
>  	}
>  
> -	if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT &&
> -	    pool->p.flags & PP_FLAG_PAGE_FRAG)
> -		return -EINVAL;
> -
>  	if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
>  		return -ENOMEM;
>  
> 



Git bisection log:

-------------------------------------------------------------------------------
git bisect start
# good: [bfc484fe6abba4b89ec9330e0e68778e2a9856b2] Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
git bisect good bfc484fe6abba4b89ec9330e0e68778e2a9856b2
# bad: [e851dfae4371d3c751f1e18e8eb5eba993de1467] Merge tag 'kgdb-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux
git bisect bad e851dfae4371d3c751f1e18e8eb5eba993de1467
# bad: [dcd68326d29b62f3039e4f4d23d3e38f24d37360] Merge tag 'devicetree-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
git bisect bad dcd68326d29b62f3039e4f4d23d3e38f24d37360
# bad: [b7b98f868987cd3e86c9bd9a6db048614933d7a0] Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
git bisect bad b7b98f868987cd3e86c9bd9a6db048614933d7a0
# bad: [9fd3d5dced976640f588e0a866b9611db2d2cb37] net: ethernet: ave: Add compatible string and SoC-dependent data for NX1 SoC
git bisect bad 9fd3d5dced976640f588e0a866b9611db2d2cb37
# good: [a96d317fb1a30b9f323548eb2ff05d4e4600ead9] ethernet: use eth_hw_addr_set()
git bisect good a96d317fb1a30b9f323548eb2ff05d4e4600ead9
# good: [f5396b8a663f7a78ee5b75a47ee524b40795b265] ice: switchdev slow path
git bisect good f5396b8a663f7a78ee5b75a47ee524b40795b265
# good: [20c3d9e45ba630a7156d682a40988c0e96be1b92] hamradio: use dev_addr_set() for setting device address
git bisect good 20c3d9e45ba630a7156d682a40988c0e96be1b92
# bad: [a64b442137669c9e839c6a70965989b01b1253b7] net: dpaa2: add support for manual setup of IRQ coalesing
git bisect bad a64b442137669c9e839c6a70965989b01b1253b7
# good: [30fc7efa38f21afa48b0be6bf2053e4c10ae2c78] net, neigh: Reject creating NUD_PERMANENT with NTF_MANAGED entries
git bisect good 30fc7efa38f21afa48b0be6bf2053e4c10ae2c78
# bad: [13ad5ccc093ff448b99ac7e138e91e78796adb48] dt-bindings: net: dsa: qca8k: Document qca,sgmii-enable-pll
git bisect bad 13ad5ccc093ff448b99ac7e138e91e78796adb48
# good: [40088915f547b52635f022c1e1e18df65ae3153a] Merge branch 'octeontx2-af-miscellaneous-changes-for-cpt'
git bisect good 40088915f547b52635f022c1e1e18df65ae3153a
# bad: [fdbf35df9c091db9c46e57e9938e3f7a4f603a7c] dt-bindings: net: dsa: qca8k: Add SGMII clock phase properties
git bisect bad fdbf35df9c091db9c46e57e9938e3f7a4f603a7c
# bad: [bacc8daf97d4199316328a5d18eeafbe447143c5] xen-netback: Remove redundant initialization of variable err
git bisect bad bacc8daf97d4199316328a5d18eeafbe447143c5
# bad: [d00e60ee54b12de945b8493cf18c1ada9e422514] page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA
git bisect bad d00e60ee54b12de945b8493cf18c1ada9e422514
# first bad commit: [d00e60ee54b12de945b8493cf18c1ada9e422514] page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA
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