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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251110180715.602807-1-pasha.tatashin@soleen.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9B050140006 X-Stat-Signature: xjzryy87bmzpopj5b9zuxu38nqdgoziq X-Rspam-User: X-HE-Tag: 1763105419-6004 X-HE-Meta: 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 vEVaSVJc 45DdY3/uiwYVyUlsDrE8D4x4fkq7iV8MTOOGK68JNpvi8r6AgPXZi1WFnDQiQcX67w6xtpGbAl42VerXhLwfyvFa4wE6qdDV8MLEqs2PTw+2x/VaYD/Nqvwqaq3K2CAjCgQxfKWbUBp9UV+lu9fDjE1znbsblJeBwRbcOkARZmEmoDH3nqgDo2EXBrilpDXme9I8dIUyjMQ9Jl8Ifkrjn/qwcZXubMtmLKJ48+2yTlNhf28TiRFDoTtzuVdZqp9C1PBQg6n0/i8BN/UG0vai6CcnxEgXJD+3ocvYQHwc/Ot3N7Ji2STIE9c/NzXTImwZRKHGKcM7PMH4Xf3tuIdEUMcKsfg== 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 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.