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Subject: Re: [PATCH net-next v6] page_pool: disable dma mapping support for
 32-bit arch with 64-bit DMA
To:     Guillaume Tucker <guillaume.tucker@collabora.com>,
        <davem@davemloft.net>, <kuba@kernel.org>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linuxarm@openeuler.org>, <hawk@kernel.org>,
        <ilias.apalodimas@linaro.org>, <akpm@linux-foundation.org>,
        <peterz@infradead.org>, <will@kernel.org>, <jhubbard@nvidia.com>,
        <yuzhao@google.com>, <mcroce@microsoft.com>,
        <fenghua.yu@intel.com>, <feng.tang@intel.com>, <jgg@ziepe.ca>,
        <aarcange@redhat.com>, <guro@fb.com>,
        "kernelci@groups.io" <kernelci@groups.io>
References: <20211013091920.1106-1-linyunsheng@huawei.com>
 <b9c0e7ef-a7a2-66ad-3a19-94cc545bd557@collabora.com>
From:   Yunsheng Lin <linyunsheng@huawei.com>
Message-ID: <1090744a-3de6-1dc2-5efe-b7caae45223a@huawei.com>
Date:   Tue, 9 Nov 2021 20:02:38 +0800
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On 2021/11/9 17:58, Guillaume Tucker wrote:
> 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.

The patch below is removing the dma mapping support in page pool
for 32 bit systems with 64 bit dma address, so it seems there
is indeed a a drvier using the the page pool with PP_FLAG_DMA_MAP
flags set in a 32 bit systems with 64 bit dma address.

It seems we might need to revert the below patch or implement the
DMA-mapping tracking support in the driver as mentioned in the below
commit log.

which ethernet driver do you use in your system?

> 
> Best wishes,
> Guillaume
> 
> 
> GitHub: https://github.com/kernelci/kernelci-project/issues/71
> 
> -------------------------------------------------------------------------------
> 
> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> * 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:
> 
> -------------------------------------------------------------------------------
> 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
> -------------------------------------------------------------------------------
> .
>