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 4E50323D7CD for ; Fri, 14 Nov 2025 07:30:18 +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=1763105419; cv=none; b=oDPcvu8/0QxN+5EdqUj8VOTEoDIXrSqXHJOKo1kUQ3djo145htyew9nvO9vC1IXqwKPp8fHtVp3OQSqXMVRC+9YciC7GiaWmOpVdyKeiub2+y7/mJ1DA61xcTeKNFkZe/8+cLJxtqVIJoLFZNwcigIuNq3goqgKdz/98dUkwP3M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763105419; c=relaxed/simple; bh=ofHq5p9Z3RmRzcDHoqIGOqiKwshUcCL3Eo8rh8N1eow=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QUoEtJyHJgMCkbufShmW/2yvTwztj7Y3PxLERKMJ88Ht3C2xHmSetSdUnC8v8fcw1lcH2P5D/eV8s4+JdjAglWocQpSwA1j0Qdb1VKecl1sSWqzhZy5M0tigQcBbfTKscoWdZ5rJm7jaOQ/dmhxd0BKR8rvnO6ELhGkJs6JI3Rk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dall0xEi; 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="dall0xEi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADD36C4CEF8; Fri, 14 Nov 2025 07:30:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763105418; bh=ofHq5p9Z3RmRzcDHoqIGOqiKwshUcCL3Eo8rh8N1eow=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dall0xEicEsJMWwgN246NGUG4Wt2t1VsFM3lAbgskABkVYqL1yPKR9ohMLRjTEbgl tOnE84T+jml7UGQaiA6+qdmCUCBW9t5lNIranNvkvTLuIH65oNGHt51yDu0lqkJVS6 kN34kkvGuzaxDIws+ZwdwOBVQuvj55/E/6rDCUx+nKohXQi2+qcJhgLpcbfho1Ep8r cPQC7bj+ktc8Kt5wWtbCy2LZiKLVapRNbbTcZBxCyTmocKbHflDyxR/OTFgHkqadeo NkwzniLBj861/jzwgronYdq5Eh6kVGynd+ps9lYO3/EpVYIg13iY8xZbYtIeR+pNXA z78J7/QWR2USg== Date: Fri, 14 Nov 2025 09:30:11 +0200 From: Mike Rapoport To: Pasha Tatashin Cc: akpm@linux-foundation.org, graf@amazon.com, pratyush@kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH] liveupdate: kho: Enable KHO by default Message-ID: References: <20251110180715.602807-1-pasha.tatashin@soleen.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20251110180715.602807-1-pasha.tatashin@soleen.com> On Mon, Nov 10, 2025 at 01:07:15PM -0500, Pasha Tatashin wrote: > Upcoming LUO requires KHO for its operations, the requirement to place > both KHO=on and liveupdate=on becomes redundant. Set KHO to be enabled > by default. I though more about this and it seems too much of a change. kho=1 enables scratch areas and that significantly changes how free pages are distributed in the free lists. Let's go with a Kconfig option we discussed of-list: (this is on top of the current mmotm/mm-nonmm-unstable) >From 823299d80aa4f7c16ef6cfd798a19e1dfe1a91ab Mon Sep 17 00:00:00 2001 From: Pasha Tatashin Date: Fri, 14 Nov 2025 09:27:47 +0200 Subject: [PATCH] kho: Allow KHO to be enabled by default Upcoming LUO requires KHO for its operations, the requirement to place both KHO=on and liveupdate=on becomes reduntant. Let's allow KHO to be enabled by default, and CONFIG_LIVEUPDATE can select this CONFIG. Signed-off-by: Pasha Tatashin Signed-off-by: Mike Rapoport (Microsoft) --- kernel/liveupdate/Kconfig | 8 ++++++++ kernel/liveupdate/kexec_handover.c | 2 +- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/liveupdate/Kconfig b/kernel/liveupdate/Kconfig index d7344d347f69..25c9a4d7781f 100644 --- a/kernel/liveupdate/Kconfig +++ b/kernel/liveupdate/Kconfig @@ -63,4 +63,12 @@ config KEXEC_HANDOVER_DEBUGFS Also, enables inspecting the KHO fdt trees with the debugfs binary blobs. +config KEXEC_HANDOVER_ENABLE_DEFAULT + bool "Enable kexec handover by default" + depends on KEXEC_HANDOVER + help + Enable the kexec handover by default. It is equivalent of passing + kho=on via kernel parameter, and can be overwritten to off via + kho=off. + endmenu diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index 568cd9fe9aca..23a3df297bb3 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -51,7 +51,7 @@ union kho_page_info { static_assert(sizeof(union kho_page_info) == sizeof(((struct page *)0)->private)); -static bool kho_enable __ro_after_init = true; +static bool kho_enable __ro_after_init = IS_ENABLED(CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT); bool kho_is_enabled(void) { -- 2.50.1 -- Sincerely yours, Mike.