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 0F1742AD1F; Mon, 10 Nov 2025 13:01:24 +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=1762779685; cv=none; b=pO3cF+iYaX0maUOslt9CTfOI4w1YfYink91GWkOcN9TLopy/Do5obuSLlT0R6yYFopzAIrsex2pTse+xyKW8v/bq04ZKvWA+ksPmlYlyVDpZ0zlu4vaSJ5a5TDAdEGrkGbhrCwlZlwuzblDVB3ckN5xKqqD6TkXRuW6Oal65rRE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762779685; c=relaxed/simple; bh=Nty6eYvSZQwOVNMjVt6MpJ2VRDmLEsf0ItJ+R2b2b5Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Rs1/VGu0SoHQxbNwbHcb3T890+grdELpeRqIoXmrVVJ94hNYk53lHZvpqCmyCewzdGXBxlSX6OjnrWRfcns3oDFWU7R2gdtqsFKVf2sqJVXyFTNg+6pigG1T3+l870GOJ1KrZ+0fvbTJSaiZyc1DcidVQyyBsS1hnThnf1VKwT8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WBsr08XW; 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="WBsr08XW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CDC7FC4CEFB; Mon, 10 Nov 2025 13:01:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762779684; bh=Nty6eYvSZQwOVNMjVt6MpJ2VRDmLEsf0ItJ+R2b2b5Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; 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> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251107210526.257742-3-pasha.tatashin@soleen.com> 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.