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Fri, 01 May 2026 16:45:06 -0700 (PDT) From: Coiby Xu To: kexec@lists.infradead.org Cc: Andrew Morton , Sourabh Jain , Baoquan He , Dave Young , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Jonathan Corbet , Shuah Khan , Coiby Xu , linux-doc@vger.kernel.org (open list:DOCUMENTATION), linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 8/9] crash_dump: Disallow configfs/crash_dm_crypt_key/reuse if CONFIG_CRASH_HOTPLUG enabled Date: Sat, 2 May 2026 07:43:37 +0800 Message-ID: <20260501234342.2518281-9-coiby.xu@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260501234342.2518281-1-coiby.xu@gmail.com> References: <20260501234342.2518281-1-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-Transfer-Encoding: 8bit If CONFIG_CRASH_HOTPLUG is enabled, dm-crypt keys saved to reserved memory will be took 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 CONFIG_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 --- Documentation/admin-guide/kdump/kdump.rst | 9 ++++++--- kernel/crash_dump_dm_crypt.c | 14 +++++++++++--- 2 files changed, 17 insertions(+), 6 deletions(-) diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index 7587caadbae1..73f2e9500c60 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 @@ -593,7 +594,9 @@ with /sys/kernel/config/crash_dm_crypt_keys for setup, # To support CPU/memory hot-plugging, reuse keys already saved to reserved # memory - echo true > /sys/kernel/config/crash_dm_crypt_key/reuse + # Note if CONFIG_CRASH_HOTPLUG is enabled, this API is totally unnecessary + # thus will be disabled. + echo true > /sys/kernel/config/crash_dm_crypt_keys/reuse 2. Load the dump-capture kernel diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index 36e51807d94f..7a7cae17f578 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -304,6 +304,11 @@ static ssize_t config_keys_reuse_store(struct config_item *item, bool val; int r; + if (IS_ENABLED(CONFIG_CRASH_HOTPLUG)) { + pr_info("CONFIG_CRASH_HOTPLUG already enabled"); + return -EINVAL; + } + if (!kexec_crash_image || !kexec_crash_image->dm_crypt_keys_addr) { pr_info("dm-crypt keys haven't be saved to crash-reserved memory\n"); return -EINVAL; @@ -486,15 +491,18 @@ int crash_load_dm_crypt_keys(struct kimage *image) void kexec_file_post_load_cleanup_dm_crypt(struct kimage *image) { /* - * For CPU/memory hot-plugging, the kdump image will be reloaded. Prevent - * keys_header from being cleaned up during unloading when - * is_dm_key_reused=true + * For CPU/memory hot-plugging without CONFIG_CRASH_HOTPLUG, the whole kdump + * image will be reloaded. Prevent keys_header from being cleaned up during + * unloading when is_dm_key_reused=true */ if (!is_dm_key_reused) { kfree_sensitive(keys_header); keys_header = NULL; } + if (IS_ENABLED(CONFIG_CRASH_HOTPLUG)) + image->dm_crypt_keys_addr = 0; + if (mutex_is_locked(&config_keys_subsys.su_mutex)) mutex_unlock(&config_keys_subsys.su_mutex); } -- 2.54.0