On Wed, Aug 05, 2026 at 05:39:28PM +0530, Sourabh Jain wrote:
On 29/07/26 09:06, 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. Reserving image->dm_crypt_keys_addr is also unnecessary. 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") Signed-off-by: Coiby Xu <[email protected]> --- Documentation/admin-guide/kdump/kdump.rst | 16 ++++++++++------ kernel/crash_dump_dm_crypt.c | 23 ++++++++++++++++++++--- 2 files changed, 30 insertions(+), 9 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 echo yes > /sys/kernel/crash_dm_crypt_keys/restore +For CPU/memory hot-plugging, you can reuse keys already saved to reserved +memory before reloading the kdump image, + echo true > /sys/kernel/config/crash_dm_crypt_keys/reuse + +Note if crash hotplug is supported, this API is totally unnecessary thus will +be disabled automatically. + Contact ======= diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index b5b78656cf06..46d6b31c3ca4 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -310,6 +310,15 @@ static ssize_t config_keys_reuse_show(struct config_item *item, char *page) return sysfs_emit(page, "%d\n", is_dm_key_reused); } +static bool crash_hotplug_support(struct kimage *image) +{ +#ifdef CONFIG_CRASH_HOTPLUG + return image->hotplug_support;I don't think it is good idea to access kexec_crash_image properties without holding the kexec lock.
Thanks for raising the concern! Let's discuss this issue in [PATCH v3 03/10].
Also, would it make sense to move this API somewhere else?
Can you help me understand why to move this API? Is it because using ifdef in .c file is discouraged?
- Sourabh Jain
[...] -- Best regards, Coiby
