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[34.85.221.182]) by smtp.gmail.com with ESMTPSA id 00721157ae682-78fb44f0d57sm57949307b3.31.2025.12.23.12.15.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Dec 2025 12:15:10 -0800 (PST) From: Pasha Tatashin To: akpm@linux-foundation.org, pasha.tatashin@soleen.com, rppt@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, pratyush@kernel.org Subject: [PATCH v1] liveupdate: separate memfd support into LIVEUPDATE_MEMFD Date: Tue, 23 Dec 2025 15:15:06 -0500 Message-ID: <20251223201506.2334991-1-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.52.0.351.gbe84eed79e-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 54F67C0010 X-Rspamd-Server: rspam10 X-Stat-Signature: 4nfjr5k4ikangrbemtehgadgrwmmofmg X-HE-Tag: 1766520912-263923 X-HE-Meta: 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 14b6BN32 xAfYFqwqKtmEej88GKQ1YD7AdITmwJKceV5XFDmK+FNUYLRB3udF1cP+CrLwyswP6twdDdGFhgeXfT7CyBiOVdfDbg2SsaT1GK7cnyywafbOsuzQ7HlHEW54B2APTq+B9H65XQKKj9efajOZzYtmjD8hLbh3eAfOHqrIqptzv5TuyHsTGBykYNnF5nWnOb51NS1nvjDi9vpQ9l2T+5NlNXcXbigAaSIuBZNu1egXPsP5zFRMfHDlQh1AE+CguYLf6fNFeIG1CMUYZ4UMVzY+1uXrC3KinloxKdXQCRSN3kQ3oHUx6VdWZcz59N/BJSnHi2SkpR218BZVsETIuEYsMOtgQMrfPGizt8wU0MzvgtBJnGU9ZjcLT6D6k1g== 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: Decouple memfd preservation support from the core Live Update Orchestrator configuration. Previously, enabling CONFIG_LIVEUPDATE forced a dependency on CONFIG_SHMEM and unconditionally compiled memfd_luo.o. However, Live Update may be used for purposes that do not require memfd-backed memory preservation. Introduce CONFIG_LIVEUPDATE_MEMFD to gate memfd_luo.o. This moves the SHMEM and MEMFD_CREATE dependencies to the specific feature that needs them, allowing the base LIVEUPDATE option to be selected independently of shared memory support. Signed-off-by: Pasha Tatashin --- kernel/liveupdate/Kconfig | 16 +++++++++++++++- mm/Makefile | 2 +- 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/kernel/liveupdate/Kconfig b/kernel/liveupdate/Kconfig index d2aeaf13c3ac..9a1a8cdcf16c 100644 --- a/kernel/liveupdate/Kconfig +++ b/kernel/liveupdate/Kconfig @@ -54,7 +54,6 @@ config KEXEC_HANDOVER_ENABLE_DEFAULT config LIVEUPDATE bool "Live Update Orchestrator" depends on KEXEC_HANDOVER - depends on SHMEM help Enable the Live Update Orchestrator. Live Update is a mechanism, typically based on kexec, that allows the kernel to be updated @@ -73,4 +72,19 @@ config LIVEUPDATE If unsure, say N. +config LIVEUPDATE_MEMFD + bool "Live update support for memfd" + depends on LIVEUPDATE + depends on MEMFD_CREATE + depends on SHMEM + help + Enable live update support for memfd regions. This allows preserving + memfd-backed memory across kernel live updates. + + This can be used to back VM memory with memfds, allowing the guest + memory to persist, or for other user workloads needing to preserve + pages. + + If unsure, say N. + endmenu diff --git a/mm/Makefile b/mm/Makefile index 9175f8cc6565..798f04233d71 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -100,7 +100,7 @@ obj-$(CONFIG_NUMA) += memory-tiers.o obj-$(CONFIG_DEVICE_MIGRATION) += migrate_device.o obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o obj-$(CONFIG_PAGE_COUNTER) += page_counter.o -obj-$(CONFIG_LIVEUPDATE) += memfd_luo.o +obj-$(CONFIG_LIVEUPDATE_MEMFD) += memfd_luo.o obj-$(CONFIG_MEMCG_V1) += memcontrol-v1.o obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o ifdef CONFIG_SWAP base-commit: cc3aa43b44bdb43dfbac0fcb51c56594a11338a8 -- 2.52.0.351.gbe84eed79e-goog