From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) (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 1F0B92E9EDA for ; Thu, 13 Nov 2025 01:41:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762998118; cv=none; b=t5UAI4CF7wNn+WCMxfp+wj6Nxkz9sbHNXmf5B75qlG4trs3aruFFb8jAcZr449hp2eZ3raxS1soWrSNMPsYgwE5l4V3713fv6x0TOQnWCyNppwQ6PxcLYgijrvzBtKufF8aoZ0acGYIg74RaCGXysWfwK0WMykabrExgDvPLmnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762998118; c=relaxed/simple; bh=9ViwniV9FjvGp479W+y41NeEEmt4+EYeSsCL3B3JmNo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HPmEhstERPEEcwARIxGR288/IG+P5D9HEWBeGKx6KSULvfirqR9OAQ0xFQfbWzP/hsAlMpLjaK30pde0LoD1+qKr7/d+xE5tT5Eq2m365L53Y456+yEBruu3UA14Xk3u0zH4GijguPTb8oImn3GnujDBxc13Vmfr9gNZtuOyA3Q= 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=Aspetcsn; arc=none smtp.client-ip=91.218.175.182 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="Aspetcsn" Message-ID: <475ed48d-1f62-4983-94a1-64e41c463c36@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1762998104; 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=DZOsuzzzQHJpIeK5WeOY1LNAVB/LXukV3KrcVp6/m18=; b=AspetcsnJtR4NjDaUovNH2yMqZTZw0RgLT/JVL7iCXS9oi67IL2u0jl/uOr0dksqvGcvUn YX+fGFhLg27XpwXq2IW5geaCJE3Xio36ngY70VFJY8922A+P+lFwyw1PcZ2+dwpoMhwRKO R85op0rSFY5KSS5iU1NU0AgVIisSR1o= Date: Wed, 12 Nov 2025 17:41:38 -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] Thanks a lot. It can work now.  The logs are as below: " # [STAGE 2] Starting post-kexec verification... # [STAGE 2] Retrieving all sessions... # [STAGE 2] Verifying contents of session 'multi-test-files-1'... # [STAGE 2] Verifying contents of session 'multi-test-files-2'... # [STAGE 2] Test data verified successfully. # [STAGE 2] Finalizing all test sessions... # [STAGE 2] Finalizing state session... # --- MULTI-SESSION KEXEC TEST PASSED --- " Yanjun.Zhu > > Pasha > >> 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