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Subject: Re: [PATCH stable v5.10 0/7] arm64: Default to 32-bit wide ZONE_DMA
To:     Greg KH <gregkh@linuxfoundation.org>
CC:     Jing Xiangfeng <jingxiangfeng@huawei.com>,
        Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        <catalin.marinas@arm.com>, <will@kernel.org>,
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        <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        Li Huafei <lihuafei1@huawei.com>
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From:   Kefeng Wang <wangkefeng.wang@huawei.com>
Message-ID: <f692a6e5-9e07-8b96-b7d3-213e6e3d071b@huawei.com>
Date:   Wed, 23 Jun 2021 16:01:10 +0800
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On 2021/6/23 15:34, Greg KH wrote:
> On Wed, Jun 23, 2021 at 03:25:10PM +0800, Kefeng Wang wrote:
>>
>>
>> On 2021/6/23 15:12, Greg KH wrote:
>>> On Wed, Jun 23, 2021 at 02:59:59PM +0800, Kefeng Wang wrote:
>>>> Hi Greg,
>>>>
>>>> There are two more patches about the ZONE_DMA[32] changes,
>>>
>>> What ZONE_DMA changes?
>>
>> See the subject, [PATCH stable v5.10 0/7] arm64: Default to 32-bit wide
>> ZONE_DMA, We asked the ARM64 ZONE_DMA change backport before, link[1]

Let's inline the link:
https://lore.kernel.org/lkml/20210303073319.2215839-1-jingxiangfeng@huawei.com/

The following 7 patches(we asked from link) has merged into lts5.10(tag: 
v5.10.22)

   4d7ed9a49b0c mm: Remove examples from enum zone_type comment
   8eaef922e938 arm64: mm: Set ZONE_DMA size based on early IORT scan
   35ec3d09ff6a arm64: mm: Set ZONE_DMA size based on devicetree's 
dma-ranges
   a9861e7fa4f8 of: unittest: Add test for of_dma_get_max_cpu_address()
   18bf6e998d08 of/address: Introduce of_dma_get_max_cpu_address()
   3fbe62ffbb54 arm64: mm: Move zone_dma_bits initialization into 
zone_sizes_init()
   407b173adfac arm64: mm: Move reserve_crashkernel() into mem_init()

but the patch "arm64: mm: Move reserve_crashkernel() into mem_init()"
has some issue, see the following discussion from Catalin,

https://lore.kernel.org/linux-devicetree/e60d643e-4879-3fc3-737d-2c145332a6d7@arm.com/
https://lore.kernel.org/linux-arm-kernel/20201119175556.18681-1-catalin.marinas@arm.com/

and yes, we met crash in lts5.10 when kexec boot due to "arm64: mm: Move 
reserve_crashkernel() into mem_init()" too, which could be fixed by
commit 2687275a5843 "arm64: Force NO_BLOCK_MAPPINGS if crashkernel 
reservation is required", and the commit 791ab8b2e3db "arm64: Ignore any 
DMA offsets in the max_zone_phys() calculation" also about DMA set,
So I only asked the two patches(both in v5.11) related ARM64 ZONE_DMA 
changes backported into lts5.10.

> 
> The subject doesn't help much, sorry, what commit does this refer to?
> What happened to it?  Was it accepted or rejected?
> 
>>>> especially the
>>>> second one, both them need be backported, thanks.
>>>
>>> Backported to where?
>>
>> stable 5.10
> 
> Why?

> 
>>>> 791ab8b2e3db - arm64: Ignore any DMA offsets in the max_zone_phys()
>>>> calculation
>>>> 2687275a5843 - arm64: Force NO_BLOCK_MAPPINGS if crashkernel reservation is
>>>> required
>>>
>>> Have you tried these patches?  Where do they need to be applied to?
>>
>> Yes, we tested it, without them, especially the second one, we will
>> meet crash when using kexec boot, also there is discussion in [2]
>> and [3] from Catalin.
> 
> These [] do not seem to be links :(
I could see the links is in the end, see 
https://lore.kernel.org/lkml/e47df0fd-0ddd-408b-2972-1b6d0a786f00@huawei.com/

> 
> thanks,
> 
> greg k-h
> .
>