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b=WBsr08XWCoMFNAwbMOQ0qNvF4Su6puJFwAVVqSGXeT6zPs3x84rtXd1S+NejmtuJx xZdr6ygbytRvjLLjSuil0yB1/WF1G2479mk8z0dDg11Wyp55cwJsF7pGl0DehEuhcZ WVy01lGJQu0UrlJOlsnE40nEMhyV2hN0PmRaLfMiIYzXqz837/kxUFMsbhOvrkv7iE unZy1naPkELeU5A3OWaTwOd54LEYSQj6e5v0JRS4ibLAAqLFQM73hnr4rGzDzaRVCZ 6L8e3xlbp4/r2UWtdNwmuPzalQnsl2O8+BHfUBH3qZdlIJoyclPpp5lAfF79lgxG3M MXR0rv+rTTjZA== Date: Mon, 10 Nov 2025 15:00:59 +0200 From: Mike Rapoport To: Pasha Tatashin Cc: pratyush@kernel.org, jasonmiu@google.com, graf@amazon.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, 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, hughd@google.com, skhawaja@google.com, chrisl@kernel.org Subject: Re: [PATCH v5 02/22] liveupdate: luo_core: integrate with KHO Message-ID: References: <20251107210526.257742-1-pasha.tatashin@soleen.com> <20251107210526.257742-3-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251107210526.257742-3-pasha.tatashin@soleen.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 90DAF40006 X-Stat-Signature: 8ryqirnpf8qwm8gc1ijz3mcw9mtc9ey3 X-Rspam-User: X-HE-Tag: 1762779685-737583 X-HE-Meta: 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 sk6EhmOj ILKikpMTUL3bjSlwUOtUlYXPeaztDRos5i3Krjjv8nXCwz9mUXwZM8Vm7+cjHoNfIkv4GYY3ebrPCPJ42+V4zy58CSg+qE2sFkJ0XWGPxfhNb9R3+94LCtH2nft1ywcAz29u/GZp9c/CJOn3J1Lk/iviqS1JY2cwaDu/vvdjoLAhVTJ9va12s4khjqA8mzUSGfJXsd2Jyk1cuXGlULoKWF7GOvdnkY6M3YgarrttOTzmnNo6AtxMFjr9euYFCj2brrxvZBtWxXCND2Ccq87tBnCzrA04PUJUywEnyFxKyNNiQ4PwNyuyXybOl/34MmnO185gMsRpCzS/tdChWu7XceiGiNHiYgPXMRRdYCbF/1lDV/sx6UCbyD618lFArkwa74f1f09VWQdKE3FePXCMp2Bgc6vPc4c/tutpVTzfvHN+Og1s= 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 Fri, Nov 07, 2025 at 04:03:00PM -0500, Pasha Tatashin wrote: > Integrate the LUO with the KHO framework to enable passing LUO state > across a kexec reboot. > > When LUO is transitioned to a "prepared" state, it tells KHO to > finalize, so all memory segments that were added to KHO preservation > list are getting preserved. After "Prepared" state no new segments > can be preserved. If LUO is canceled, it also tells KHO to cancel the > serialization, and therefore, later LUO can go back into the prepared > state. > > This patch introduces the following changes: > - During the KHO finalization phase allocate FDT blob. > - Populate this FDT with a LUO compatibility string ("luo-v1"). > > LUO now depends on `CONFIG_KEXEC_HANDOVER`. The core state transition > logic (`luo_do_*_calls`) remains unimplemented in this patch. > > Signed-off-by: Pasha Tatashin > --- ... > @@ -69,7 +197,22 @@ early_param("liveupdate", early_liveupdate_param); > */ > int liveupdate_reboot(void) > { > - return 0; > + int err; > + > + if (!liveupdate_enabled()) > + return 0; > + > + err = kho_finalize(); kho_finalize() should be really called from kernel_kexec(). We avoided it because of the concern that memory allocations that late in reboot could be an issue. But I looked at hibernate() and it does allocations on reboot->hibernate path, so adding kho_finalize() as the first step of kernel_kexec() seems fine. And if we prioritize stateless memory tracking in KHO, it won't be a concern at all. > + if (err) { > + pr_err("kho_finalize failed %d\n", err); > + /* > + * kho_finalize() may return libfdt errors, to aboid passing to > + * userspace unknown errors, change this to EAGAIN. > + */ > + err = -EAGAIN; > + } > + > + return err; > } > > /** -- Sincerely yours, Mike.