From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 71CC7212574 for ; Thu, 13 Nov 2025 19:55:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763063725; cv=none; b=KG3klJR8jemL7ik/WrcAIwYTDzTBfo9G1Ztc/lTwyATdchBTNooJxa3W8wR7ZSJDmkroxhRd862EAsL+jeeX/LtqWdn4OhKgLYtF20iKDgpDw73o0AoMAx3vGBBjbqYnzCgrnUw8kMHJ2HTnxhviChTTx1wNz0Kwo3DHyYfX0ik= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763063725; c=relaxed/simple; bh=PWjW2z8zeSGuxrTyITPsYfmV6RE9q4wi7NZa5D9Yx5c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TqHJhKE1WM/77xYYjtKFVNwRR/8i9dgXQcTFay4QJbT1MNH6MfEWUmgH1kzQ9llV4DLL00GmH0zdsstvCRJkAysQgMwX55x/l6wH9ccqy5z5NiUsrTRoJnRMptTFfMwpJ6sr0GbM/P19TxYKCN2DvC2UBWo12eEO1PL44X4hIO0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=L9Djqk54; arc=none smtp.client-ip=91.218.175.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="L9Djqk54" Message-ID: <9e144e21-a5e7-4c12-b8b0-07172787ab37@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1763063720; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zLkXsr0Dvb8T4YrcF/JXkIUXrEDLj7h5d9ku45LOQx4=; b=L9Djqk54pbG5PGyLzny7VbmE5paidw/3zQQ4qTjVQhDBG2dPTyijjqnZzzmuR1NG3ceXVd V2PY2EJQX9Nn4ZDbv8H833i3VGP5KGJWBgA5tvzbzYa+Klcorfd+npHW8FAl813NxeDYll /ebeALHHipkuCi1C1QMxMzEaUDezA4U= Date: Thu, 13 Nov 2025 11:55:10 -0800 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v9 1/9] kho: make debugfs interface optional To: Pasha Tatashin Cc: Pratyush Yadav , akpm@linux-foundation.org, brauner@kernel.org, corbet@lwn.net, graf@amazon.com, jgg@ziepe.ca, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, masahiroy@kernel.org, ojeda@kernel.org, rdunlap@infradead.org, rppt@kernel.org, tj@kernel.org References: <20251101142325.1326536-1-pasha.tatashin@soleen.com> <20251101142325.1326536-2-pasha.tatashin@soleen.com> <029090cf-9a4d-4f79-b857-04c3ada83323@linux.dev> <442fa82e-16ef-4bde-84eb-743450222468@linux.dev> <0735e1ef-2b65-4a54-b4d5-964fb875cd09@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Yanjun.Zhu" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 11/11/25 7:26 AM, Pasha Tatashin wrote: > On Mon, Nov 10, 2025 at 11:11 PM Zhu Yanjun wrote: >> In FC42, when I run "./luo_multi_session" >> >> # ./luo_multi_session >> # [STAGE 1] Starting pre-kexec setup for multi-session test... >> # [STAGE 1] Creating state file for next stage (2)... >> # [STAGE 1] Creating empty sessions 'multi-test-empty-1' and >> 'multi-test-empty-2'... >> # [STAGE 1] Creating session 'multi-test-files-1' with one memfd... >> # [STAGE 1] Creating session 'multi-test-files-2' with two memfds... >> # [STAGE 1] Executing kexec... >> >> Then the system hang. And via virt-viewer, a calltrace will appear. > Looks like mountroot fails, are you passing the same kernel parameters > as the during cold boot? > i.e. kexec -l -s --reuse-cmdline --initrd=[initramfs] [kernel] > > Pasha Hi, Pasha Following your advice, the following can work well. I am not sure if we can merge this commit into selftests/liveupdate mainline? commit 44764c48a658987b7729c5bc2be9fd87832cfbdf (HEAD -> linux-next/master) Author: Zhu Yanjun Date:   Thu Nov 13 11:45:21 2025 -0800     selftests/liveupdate: Fix the error "Unable to mount root fs on unknown-block"     If the initrd is not provide, the followings will appear.     "     Call Trace:         dump_stack_lvl+0x5d/0x80     vpanic+0x118/8x320     panic+0x6b/0x6b     ? do_mount_root+0x115/0x130      mount_root_generic+0x1cf/0x270      prepare_namespace+0x1e1/0x230      kernel_init_freeable+0x136/8x140     ?_pfx_kernel_init+0x10/0x10      kernel_init+0x1a/0x140      ret_from_fork+0x130/0x1a8      ?_pfx_kernel_init+0x10/0x10      ret_from_fork_asm+0x1a/0x30            Kernel Offset: 0x3000000 from Oxffffffff81000000     "     Signed-off-by: Zhu Yanjun diff --git a/tools/testing/selftests/liveupdate/do_kexec.sh b/tools/testing/selftests/liveupdate/do_kexec.sh index bb396a92c3b8..4ee59abd0dd4 100755 --- a/tools/testing/selftests/liveupdate/do_kexec.sh +++ b/tools/testing/selftests/liveupdate/do_kexec.sh @@ -2,5 +2,5 @@  # SPDX-License-Identifier: GPL-2.0  set -e -kexec -l -s --reuse-cmdline /boot/bzImage +kexec -l -s --reuse-cmdline /boot/bzImage --initrd /boot/initramfs-`uname -r`.img  kexec -e Thanks a lot. Yanjun.Zhu >> The call trace is in the attachment. >> >> Yanjun.Zhu >> >> 在 2025/11/10 7:26, Pasha Tatashin 写道: >>> On Mon, Nov 10, 2025 at 8:16 AM Pratyush Yadav wrote: >>>> On Sun, Nov 09 2025, Zhu Yanjun wrote: >>>> >>>>> 在 2025/11/8 10:13, Pasha Tatashin 写道: >>>>>> On Fri, Nov 7, 2025 at 6:36 PM Yanjun.Zhu wrote: >>>>>>> On 11/7/25 4:02 AM, Pasha Tatashin wrote: >>>>>>>> On Fri, Nov 7, 2025 at 7:00 AM Pasha Tatashin wrote: >>>>>>>>>> Hi, Pasha >>>>>>>>>> >>>>>>>>>> In our previous discussion, we talked about counting the number of times >>>>>>>>>> the kernel is rebooted via kexec. At that time, you suggested adding a >>>>>>>>>> variable in debugfs to keep track of this count. >>>>>>>>>> However, since debugfs is now optional, where would be an appropriate >>>>>>>>>> place to store this variable? >>>>>>>>> It is an optional config and can still be enabled if the live update >>>>>>>>> reboot number value needs to be accessed through debugfs. However, >>>>>>>>> given that debugfs does not guarantee a stable interface, tooling >>>>>>>>> should not be built to require these interfaces. >>>>>>>>> >>>>>>>>> In the WIP LUO [1] I have, I pr_info() the live update number during >>>>>>>>> boot and also store it in the incoming LUO FDT tree, which can also be >>>>>>>>> accessed through this optional debugfs interface. >>>>>>>>> >>>>>>>>> The pr_info message appears like this during boot: >>>>>>>>> [ 0.000000] luo: Retrieved live update data, liveupdate number: 17 >>>>>>>>> >>>>>>>>> Pasha >>>>>>>> Forgot to add link to WIP LUOv5: >>>>>>>> [1] https://github.com/soleen/linux/tree/luo/v5rc04 >>>>>>> Thanks a lot. I’ve carefully read this commit: >>>>>>> https://github.com/soleen/linux/commit/60205b9a95c319dc9965f119303a1d83f0ff08fa. >>>>>>> >>>>>>> To be honest, I’d like to run some tests with who/luo, including the >>>>>>> selftest for kho/luo. Could you please share the steps with me? >>>>>>> >>>>>>> If the testing steps have already been documented somewhere, could you >>>>>>> please share the link? >>>>>> Currently the test performs in-kernel tests for FLB data, it creates a >>>>>> number of FLB for every registered LUO file-handler, which at the >>>>>> moment is only memfd. >>>>>> >>>>>> It works together with any of the kexec based live update tests. In >>>>>> v5, I introduce two tests: >>>>>> luo_kexec_simple >>>>>> luo_multi_session >>>>>> >>>>>> For example, with luo_multi_session: >>>>> Hi, Pasha >>>>> >>>>> I enabled "CONFIG_LIVEUPDATE=y" >>>>> >>>>> # ./luo_multi_session >>>>> 1..0 # SKIP Failed to open /dev/liveupdate. Is the luo module loaded? >>>>> >>>>> # ls /dev/liveupdate >>>>> ls: cannot access '/dev/liveupdate': No such file or directory >>>>> >>>>> # grep "LIVEUPDATE" -inrHI /boot/config-`uname -r` >>>>> /boot/config-next-20251107-luo+:349:CONFIG_LIVEUPDATE=y >>>>> /boot/config-next-20251107-luo+:11985:CONFIG_LIVEUPDATE_TEST=y >>>>> >>>>> I made tests on FC42. But /dev/liveupdate is missing. >>>> You need to add liveupdate=1 to your kernel cmdline to enable LUO and >>>> get /dev/liveupdate. >>> +1, kernel parameters require: kho=1 liveupdate=1 >>> >>>> Pasha, your LUO series doesn't add the liveupdate parameter to >>>> kernel-parameters.txt. I think it should be done in the next version to >>>> this parameter is discoverable. >>> Yeah, that is missing, I will update that in a standalone patch, or in >>> a next version. >>> >>> Thanks, >>> Pasha >> -- >> Best Regards, >> Yanjun.Zhu