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AJvYcCWsbGZM5UpsdAuXwQSsBgUEAAC7We/e4BZ6GHOW3mei16QhXwlUwPZ88NPsVhdAcotrmfMWx1FkKA==@kvack.org X-Gm-Message-State: AOJu0Yyi0glqyguWteFfDELH3LXu0vYGfbACyERUH5AajA4SMmSm7C/6 B4Hg3KYYEv9wEXvwjMRuL82lsoMenYmZno/LDo2gFeEwud2yVI3LZXMRMYLMxo79sNtD72bawDp 7KG2r+VK2HMeIgPDfoOL+kKC3DlahXXj5ve4SivJxgA== X-Gm-Gg: ASbGncsSc3CEVdI6hr3CaLTLzvg4sR1RSinj4z1d4NtwybEF6IcxnnAJAvfCkfzq4FS rfoGRjcV/3bAWJGZcTNBk0D6HlLY8bJOFysF4tLv4Ys7PIEEXROFkW6lS73nKKXcXuAInH03H1S B8fkuL775dR3g/sVxCjrzbMUmOiiiSpW5Gxfu3u+TX X-Google-Smtp-Source: AGHT+IH9AiO07plJSRhLB6tkJdXaDFzPn2pHd+a7L3X+gKjm+z/Fz4czzaEUCOxKugIFDOgFxL19MklfYzAdFZ2DkVY= X-Received: by 2002:a05:622a:5811:b0:494:9d34:fca5 with SMTP id d75a77b69052e-49f3394f70emr7714631cf.13.1748023701929; Fri, 23 May 2025 11:08:21 -0700 (PDT) MIME-Version: 1.0 References: <20250515182322.117840-1-pasha.tatashin@soleen.com> In-Reply-To: From: Pasha Tatashin Date: Fri, 23 May 2025 14:07:45 -0400 X-Gm-Features: AX0GCFt9InSi-jbnPqjcDUibRJENQKP67YavT0G51MPVz1pVL-VvRvyfzD-NRvg Message-ID: Subject: Re: [RFC v2 00/16] Live Update Orchestrator To: Mike Rapoport Cc: pratyush@kernel.org, jasonmiu@google.com, graf@amazon.com, changyuanl@google.com, 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, ptyadav@amazon.de Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: DC3A840003 X-Stat-Signature: 9dwhwz7rgncjny3o9yzbaog64pi6qpkr X-Rspam-User: X-HE-Tag: 1748023702-955486 X-HE-Meta: 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 ShK0HQLY RyGPl6xRXfAhW/+e3GKalAfbZlfVm9bloEWUdbSDw8QGl8apJeSrYmdNpmEPQraCpxPPok1bvM+9DCd2YVEcDlmRpAg1WSVGYeXp04or/ezyzncYN2NcKKfvZTEMTTXo0wM3pvBxTwa2pglup+XjmRfEIUcoILBjgMLwd/ZkIqiAuvg06fbViWhDb+sT8ANUxVGpI2HkIYesayR+E6+kF41z4pa5CI2FZnnduEyWSMe5EtPR1xXBjYPR5Yj9EEdtqiO/YKowYHDZuLIa1rlDTGqRAl2x9PP93FLy1VSzWGc5Sl4zjreaAlr76PadxaHfiJD7YIt3JoaorIws4eidOXyhQDIkPqF4xb9EYvoiz7kb4r/aq7glcEm7KnA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, May 20, 2025 at 3:25=E2=80=AFAM Mike Rapoport wro= te: > > Hi Pasha, > > On Thu, May 15, 2025 at 06:23:04PM +0000, Pasha Tatashin wrote: > > This v2 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 [1] 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/rfc-v2 > > > > What is Live Update? > > Live Update is a specialized reboot process where selected kernel > > resources (memory, file descriptors, and eventually devices) are kept > > operational or their state preserved across a kernel transition (e.g., > > via kexec). For certain resources, DMA and interrupt activity might > > continue with minimal interruption during the kernel reboot. > > > > LUO v2 Overview: > > LUO v2 provides a framework for coordinating live updates. It features: > > State Machine: Manages the live update process through states: > > NORMAL, PREPARED, FROZEN, UPDATED. > > > > KHO Integration: > > > > LUO programmatically drives KHO's finalization and abort sequences. > > KHO's debugfs interface is now optional configured via > > CONFIG_KEXEC_HANDOVER_DEBUG. > > > > LUO preserves its own metadata via KHO's kho_add_subtree and > > kho_preserve_phys() mechanisms. > > I've only had time to skip through the patches, one thing that came to mi= nd > was that since LUO is quite tightly coupled with KHO maybe we'll put them > together in, say, kernel/liveupdate? Thank you Mike, yes, a good idea, I also thought that it would make sense for them to be in the same place, but initially I thought perhaps KHO should be moved to misc/liveupdate/, but since it is already landing in kernel/kexec_*, and it works with a bunch of core kernel subsystems it makes sense to move LUO and KHO together under kernel/liveupdate/ Pasha