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>
 <1090744a-3de6-1dc2-5efe-b7caae45223a@huawei.com>
 <644e10ca-87b8-b553-db96-984c0b2c6da1@collabora.com>
From:   Yunsheng Lin <linyunsheng@huawei.com>
Message-ID: <93173400-1d37-09ed-57ef-931550b5a582@huawei.com>
Date:   Mon, 15 Nov 2021 11:34:59 +0800
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On 2021/11/12 17:21, Guillaume Tucker wrote:
> On 09/11/2021 12:02, Yunsheng Lin wrote:
>> 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?
> 
> Thanks for taking a look and sorry for the slow reply.  Here's a
> booting test job with LPAE disabled:
> 
>     https://linux.kernelci.org/test/plan/id/618dbb81c60c4d94503358f1/
>     https://storage.kernelci.org/mainline/master/v5.15-12452-g5833291ab6de/arm/multi_v7_defconfig/gcc-10/lab-collabora/baseline-nfs-rk3288-rock2-square.html#L812
> 
> [    8.314523] rk_gmac-dwmac ff290000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx
> 
> So the driver is drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c

Thanks for the report, this patch seems to cause problem for 32-bit
system with LPAE enabled.

As LPAE seems like a common feature for 32 bits system, this patch
might need to be reverted.

@Jesper, @Ilias, what do you think?

> 
> 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
>>> -------------------------------------------------------------------------------
>>> .
>>>
> 
> .
>