linux-kernel - Re: [PATCH v2] arm64/kdump: pass dm-crypt keys to kdump kernel

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Message-ID: <aVzFW1_32EwyE2kj@Rk>
Date: Tue, 6 Jan 2026 16:41:14 +0800
From: Coiby Xu <coxu@...hat.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org, 
	Arnaud Lefebvre <arnaud.lefebvre@...ver-cloud.com>, Baoquan he <bhe@...hat.com>, Dave Young <dyoung@...hat.com>, 
	Kairui Song <ryncsn@...il.com>, Pingfan Liu <kernelfans@...il.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Rob Herring <robh@...nel.org>, 
	Saravana Kannan <saravanak@...nel.org>, open list <linux-kernel@...r.kernel.org>, 
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2] arm64/kdump: pass dm-crypt keys to kdump kernel

On Tue, Jan 06, 2026 at 09:05:49AM +0100, Krzysztof Kozlowski wrote:
>On Tue, Jan 06, 2026 at 02:22:30PM +0800, Coiby Xu wrote:
>> CONFIG_CRASH_DM_CRYPT has been introduced to support LUKS-encrypted
>> device dump target by addressing two challenges [1],
>>  - Kdump kernel may not be able to decrypt the LUKS partition. For some
>>    machines, a system administrator may not have a chance to enter the
>>    password to decrypt the device in kdump initramfs after the 1st kernel
>>    crashes
>>
>>  - LUKS2 by default use the memory-hard Argon2 key derivation function
>>    which is quite memory-consuming compared to the limited memory reserved
>>    for kdump.
>>
>> To also enable this feature for ARM64, we only need to add device tree
>> property dmcryptkeys [2] as similar to elfcorehdr to pass the memory
>> address of the stored info of dm-crypt keys to the kdump kernel.
>>
>> [1] https://lore.kernel.org/all/20250502011246.99238-1-coxu@redhat.com/
>> [2] https://github.com/devicetree-org/dt-schema/pull/181
>>
>> Cc: Arnaud Lefebvre <arnaud.lefebvre@...ver-cloud.com>
>> Cc: Baoquan he <bhe@...hat.com>
>> Cc: Dave Young <dyoung@...hat.com>
>> Cc: Kairui Song <ryncsn@...il.com>
>> Cc: Pingfan Liu <kernelfans@...il.com>
>> Cc: Andrew Morton <akpm@...ux-foundation.org>
>> Cc: Krzysztof Kozlowski <krzk@...nel.org>
>> Signed-off-by: Coiby Xu <coxu@...hat.com>
>> ---
>> v2
>> - Krzysztof
>>   - Use imperative mood for commit message
>>   - Add dt-schema ABI Documentation
>> - Don't print dm-crypt keys address via pr_debug
>
>Your changelog should explicitly document that this has external
>dependency on dtschema pull request, so that maintainers know that.

Thanks for the lightning-fast reply!

And thanks for the reminder! I didn't know the dtschema pull request is
regarded as a dependency. Currently, I only add the dtschema pull
request URL to the commit message. I'll also include it in the
changelog.

>
>Also, in the future:
>Do not attach (thread) your patchsets to some other threads (unrelated
>or older versions). This buries them deep in the mailbox and might
>interfere with applying entire sets. See also:
>https://elixir.bootlin.com/linux/v6.16-rc2/source/Documentation/process/submitting-patches.rst#L830

Thanks for pointing me to the above documentation! I thought adding
In-Reply-To to the V1 patch can provide better context since it's a
single patch. It seems this is not true for Devicetree. Is it because of
the documentation change thus we should treat it more like a multi-patch
series?

>
>Best regards,
>Krzysztof
>

-- 
Best regards,
Coiby