From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1C248C79F8C for ; Wed, 9 Sep 2026 05:46:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=SBM06s4g0kz7WS7W0WwfUM/yQZv7aEJIy1mSj1Suf2A=; b=rXpdtYYpakPqRh3IpVvrGMHKXL 8NAPTj2qHD0hbtB/hPUlXuCoIZFA1YRwJZGYXpjx54K0JXW/p/8HqPFruME5ZL7Wpa1oEUc8L9XKl /jt+t/Yo5RquWpkxOXMplZWCLdLqorWfCUEZFkEgC1bes+OZk3ZUrqxbuEb/JpZfyC6pJXIJjyRXY GfM0L2LTKC+Tfb/H+f5l/giz1LkmPFprXknqDlL2PLJqJSMLrHNTNH8pZnrthvsR06vcWEZWw67Mc dBXEC9c3lOokFRpeF8HtRs30lUW3qyV/DUstpKJazcLLNROKFwwsuqENt1BtcMl2BL9Hy3AIROpcL t0hwl/OA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4B8I-0000000Aoeh-2zhF; Wed, 09 Sep 2026 05:46:06 +0000 Received: from [50.53.43.113] (helo=[192.168.254.34]) by bombadil.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4B8H-0000000AoeL-15Wq; Wed, 09 Sep 2026 05:46:05 +0000 Message-ID: Date: Tue, 8 Sep 2026 22:46:03 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 8/9] crash_dump: Disallow configfs/crash_dm_crypt_key/reuse if crash hotplug supported To: Coiby Xu , kexec@lists.infradead.org Cc: 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 References: <20260909003657.1570544-1-coiby.xu@gmail.com> <20260909003657.1570544-9-coiby.xu@gmail.com> Content-Language: en-US From: Randy Dunlap In-Reply-To: <20260909003657.1570544-9-coiby.xu@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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, > 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 > ======= > -- ~Randy