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Wed, 09 Sep 2026 06:35:15 -0700 (PDT) From: Coiby Xu X-Google-Original-From: Coiby Xu Date: Wed, 9 Sep 2026 21:33:02 +0800 To: Randy Dunlap Cc: kexec@lists.infradead.org, Andrew Morton , Sourabh Jain , Baoquan He , Dave Young , Pratyush Yadav , Will Deacon , linux-arm-kernel@lists.infradead.org, Jinjie Ruan , Mike Rapoport , Pasha Tatashin , Jonathan Corbet , Shuah Khan , "open list:DOCUMENTATION" , open list Subject: Re: [PATCH v5 8/9] crash_dump: Disallow configfs/crash_dm_crypt_key/reuse if crash hotplug supported Message-ID: References: <20260909003657.1570544-1-coiby.xu@gmail.com> <20260909003657.1570544-9-coiby.xu@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: On Tue, Sep 08, 2026 at 10:46:03PM -0700, Randy Dunlap wrote: > > >On 9/8/26 5:36 PM, Coiby Xu wrote: >> If crash hotplug is supported, dm-crypt keys saved to reserved memory >> will be taken care of automatically. Thus it doesn't make sense to use >> configfs/crash_dm_crypt_key/reuse. Not reserving >> image->dm_crypt_keys_addr makes it implicitly to disallow using this >> API. Currently x86_64 and ppc64le have implemented crash hotplug >> feature. >> >> Also update the doc accordingly. Note two doc issues are fixed as well. >> >> Fixes: 9ebfa8dcaea7 ("crash_dump: reuse saved dm crypt keys for CPU/memory hot-plugging") >> Reviewed-by: Sourabh Jain >> Signed-off-by: Coiby Xu >> --- >> Documentation/admin-guide/kdump/kdump.rst | 16 ++++++++++------ >> kernel/crash_dump_dm_crypt.c | 12 ++++++++---- >> 2 files changed, 18 insertions(+), 10 deletions(-) >> >> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst >> index 7587caadbae1..0bf2eb100a05 100644 >> --- a/Documentation/admin-guide/kdump/kdump.rst >> +++ b/Documentation/admin-guide/kdump/kdump.rst >> @@ -577,9 +577,10 @@ with /sys/kernel/config/crash_dm_crypt_keys for setup, >> >> 1. Tell the first kernel what logon keys are needed to unlock the disk volumes, >> # Add key #1 >> - mkdir /sys/kernel/config/crash_dm_crypt_keys/7d26b7b4-e342-4d2d-b660-7426b0996720 >> + VOL1_UUID=7d26b7b4-e342-4d2d-b660-7426b0996720 >> + mkdir /sys/kernel/config/crash_dm_crypt_keys/$VOL1_UUID >> # Add key #1's description >> - echo cryptsetup:7d26b7b4-e342-4d2d-b660-7426b0996720 > /sys/kernel/config/crash_dm_crypt_keys/description >> + echo cryptsetup:$VOL1_UUID > /sys/kernel/config/crash_dm_crypt_keys/$VOL1_UUID/description >> >> # how many keys do we have now? >> cat /sys/kernel/config/crash_dm_crypt_keys/count >> @@ -591,15 +592,18 @@ with /sys/kernel/config/crash_dm_crypt_keys for setup, >> cat /sys/kernel/config/crash_dm_crypt_keys/count >> 2 >> >> - # To support CPU/memory hot-plugging, reuse keys already saved to reserved >> - # memory >> - echo true > /sys/kernel/config/crash_dm_crypt_key/reuse >> - >> 2. Load the dump-capture kernel >> >> 3. After the dump-capture kerne get booted, restore the keys to user keyring > > kernel is booted, Thanks for catching this typo! I'll apply your suggestion to next version! [...] -- Best regards, Coiby