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 765A31D5147 for ; Tue, 30 Dec 2025 15:30:27 +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=1767108627; cv=none; b=A1aBhpjLUiT6663FV9vMEsl7s5paMIjC24GdPsJN7hh8KU/okTo9FxWFa4gcb/cVl4eO6tfI2ypWYbik9Jn1utgDsnpHFO1xFPqFCpcLapAgLKNlD1tfvh69cMhCFLZNuXf0W450FUtdCQ85X7YATLA+xSwNO1wRuyg2Y/7/sFo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767108627; c=relaxed/simple; bh=0dE68WcD60xA8yJuQhucOpbV5dnLhWL8/6hmbXn+bXY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TLJUX3Xc+e531bj3wh3Da0SfEGL1BgN+9sCUsA4y4UcQ0jNgk2jU/kSMyKsN7mfmacYc+jkjX0+YpVUE59aKZ1iEwRWlO5jkYNA7hJws8ZidK8hXRFKl8y52rztS9j6iBWbYRyNiVhTTLQdhP4upTcUmei9heYEKtuBhVseowcs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=B6pLAvqJ; 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="B6pLAvqJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C6F1C4CEFB; Tue, 30 Dec 2025 15:30:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767108627; bh=0dE68WcD60xA8yJuQhucOpbV5dnLhWL8/6hmbXn+bXY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=B6pLAvqJoD2wkhHEwaUeuV+6xL06aIliQcnWlG9oU1oj25ZNAGaHe5rWYLCgXpLDW uGFVrQviJPfhgjNIKlrW/m13muQqTcV+GswjaxkP2P2ybi9YBQwTC9TUYuObN/4y/J +aQGP+OLr5YiU3UEh8mmXz8uNVzMS10agnfuvaGmJhOQ70q76bzpTdJx6cDyNvGGSk O/xPfislK8xkeC31BvDqZcpPr4mZguZ+RVmVrJSyLZfDCgEMSeKUE2tY/jNEn84sIq /Tw2aI4CLTzBxyERKIFIBg4ZgiozidmfdbRBgErhUdsJVVmdTPvdQFVgzYl4edpz98 +wMvmhvQXjrDw== Date: Tue, 30 Dec 2025 17:30:21 +0200 From: Mike Rapoport To: Pasha Tatashin Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, pratyush@kernel.org Subject: Re: [PATCH v2] liveupdate: separate memfd support into LIVEUPDATE_MEMFD Message-ID: References: <20251230145321.1512630-1-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: <20251230145321.1512630-1-pasha.tatashin@soleen.com> On Tue, Dec 30, 2025 at 09:53:21AM -0500, Pasha Tatashin wrote: > 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 > Reviewed-by: Pratyush Yadav > --- > Changes v2: > - Updated testing config > - Added review-by > > kernel/liveupdate/Kconfig | 16 +++++++++++++++- > mm/Makefile | 2 +- > tools/testing/selftests/liveupdate/config | 1 + > 3 files changed, 17 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 Maybe also default LIVEUPDATE > + 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 > diff --git a/tools/testing/selftests/liveupdate/config b/tools/testing/selftests/liveupdate/config > index 91d03f9a6a39..1bfc708041bd 100644 > --- a/tools/testing/selftests/liveupdate/config > +++ b/tools/testing/selftests/liveupdate/config > @@ -5,6 +5,7 @@ CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT=y > CONFIG_KEXEC_HANDOVER_DEBUGFS=y > CONFIG_KEXEC_HANDOVER_DEBUG=y > CONFIG_LIVEUPDATE=y > +CONFIG_LIVEUPDATE_MEMFD=y then this is not needed :) > CONFIG_LIVEUPDATE_TEST=y > CONFIG_MEMFD_CREATE=y > CONFIG_TMPFS=y > -- > 2.52.0.351.gbe84eed79e-goog > -- Sincerely yours, Mike.