From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 AE6431DAC95; Tue, 26 Aug 2025 13:16:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756214192; cv=none; b=P1b7BM4M/lazrcefvn/gzHTfYI33nQPHY9ni1B7it4jtsz/ih8djycOSw90+N1Ss6odDMj39CKjISAS8DRS+kFdX9ibbepdL61iG5QGFCFQX3MzxyR6Zqq3SjdSGYRaB/fs5MNEKKQa50wABvXzgADhZMesI5fFHZ9/xeSb+Yqk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756214192; c=relaxed/simple; bh=tFb+Ondpv3Ccm4cT7YJIvIxpPOa3gBZBu7W+KGbSHs4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=h4D2HWv6H/3XrFAAkvZ5Wji2EgLk8bVwlZqHqXA7w2yzpJVd/t7KuhXROwvPvdrxF8A7J+sHHHSKkG3M/pzc6Xznx9+HnvDYCcZyM2hA+NWRcE0wWC/62dH+gkCmrR9cdYkY/ZssU4HFUY7tXt8ZjIkPyQoqK6nvPhFI3rC1hKg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jpp3MwAe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jpp3MwAe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73E44C4CEF1; Tue, 26 Aug 2025 13:16:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756214192; bh=tFb+Ondpv3Ccm4cT7YJIvIxpPOa3gBZBu7W+KGbSHs4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=jpp3MwAeRCmcs1UuVWPLSMUBFxGBC6oylqYB3I9Uzi2zxr21OZ6UbVQud/RwJFL5A JtdjMnl+UTMcT4Vgdm/+7BIHD4iduxJtj78yK3VPvpmhMG8nsPX30DSSTgLWTl+7Ku BOieUo7gY9Iyv9Bh/2rSCb931n/kxnD0i7kIOvV62Lt7fUpCQnmQtb1TmMedYESuYs Db2KWn2LhMbIvO2UWMg9WFZqHSbo4onE/E0K417i3qgQHY8Y8da+WdKX2Cy0Mz7GAQ 2eL4A+0PFwJa7uFynssXDVxGSTDsF74paRhslvfyRZw2VMr9oJmDa7gkTB0CBX5fry ZXrM1hz5JJqzQ== From: Pratyush Yadav To: Pasha Tatashin Cc: pratyush@kernel.org, jasonmiu@google.com, graf@amazon.com, changyuanl@google.com, rppt@kernel.org, dmatlack@google.com, rientjes@google.com, corbet@lwn.net, rdunlap@infradead.org, ilpo.jarvinen@linux.intel.com, kanie@linux.alibaba.com, ojeda@kernel.org, aliceryhl@google.com, masahiroy@kernel.org, akpm@linux-foundation.org, tj@kernel.org, yoann.congal@smile.fr, mmaurer@google.com, roman.gushchin@linux.dev, chenridong@huawei.com, axboe@kernel.dk, mark.rutland@arm.com, jannh@google.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, dan.j.williams@intel.com, david@redhat.com, joel.granados@kernel.org, rostedt@goodmis.org, anna.schumaker@oracle.com, song@kernel.org, zhangguopeng@kylinos.cn, linux@weissschuh.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, gregkh@linuxfoundation.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, dakr@kernel.org, bartosz.golaszewski@linaro.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, yesanishhere@gmail.com, Jonathan.Cameron@huawei.com, quic_zijuhu@quicinc.com, aleksander.lobakin@intel.com, ira.weiny@intel.com, andriy.shevchenko@linux.intel.com, leon@kernel.org, lukas@wunner.de, bhelgaas@google.com, wagi@kernel.org, djeffery@redhat.com, stuart.w.hayes@gmail.com, lennart@poettering.net, brauner@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, saeedm@nvidia.com, ajayachandra@nvidia.com, jgg@nvidia.com, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com Subject: Re: [PATCH v3 00/30] Live Update Orchestrator In-Reply-To: <20250807014442.3829950-1-pasha.tatashin@soleen.com> References: <20250807014442.3829950-1-pasha.tatashin@soleen.com> Date: Tue, 26 Aug 2025 15:16:22 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Hi Pasha, On Thu, Aug 07 2025, Pasha Tatashin wrote: > This series introduces the LUO, a kernel subsystem designed to > facilitate live kernel updates with minimal downtime, > particularly in cloud delplyoments aiming to update without fully > disrupting running virtual machines. > > This series builds upon KHO framework by adding programmatic > control over KHO's lifecycle and leveraging KHO for persisting LUO's > own metadata across the kexec boundary. The git branch for this series > can be found at: > > https://github.com/googleprodkernel/linux-liveupdate/tree/luo/v3 > > Changelog from v2: > - Addressed comments from Mike Rapoport and Jason Gunthorpe > - Only one user agent (LiveupdateD) can open /dev/liveupdate > - With the above changes, sessions are not needed, and should be > maintained by the user-agent itself, so removed support for > sessions. If all the FDs are restored in the agent's context, this assigns all the resources to the agent. For example, if the agent restores a memfd, all the memory gets charged to the agent's cgroup, and the client gets none of it. This makes it impossible to do any kind of resource limits. This was one of the advantages of being able to pass around sessions instead of FDs. The agent can pass on the right session to the right client, and then the client does the restore, getting all the resources charged to it. If we don't allow this, I think we will make LUO/LiveupdateD unsuitable for many kinds of workloads. Do you have any ideas on how to do proper resource attribution with the current patches? If not, then perhaps we should reconsider this change? [...] -- Regards, Pratyush Yadav