linux-stable.git/kernel/kexec_handover_debugfs.c, branch linux-rolling-lts Linux kernel stable tree kho: make debugfs interface optional 2026-05-23T11:06:41+00:00 Pasha Tatashin pasha.tatashin@soleen.com 2025-11-01T14:23:17+00:00 fc1ca4f0d6be0939bac2db6f7a1fa681c8775eeb [ Upstream commit 03d3963464a43654703938a66503cd686c5fc54e ] Patch series "liveupdate: Rework KHO for in-kernel users", v9. This series refactors the KHO framework to better support in-kernel users like the upcoming LUO. The current design, which relies on a notifier chain and debugfs for control, is too restrictive for direct programmatic use. The core of this rework is the removal of the notifier chain in favor of a direct registration API. This decouples clients from the shutdown-time finalization sequence, allowing them to manage their preserved state more flexibly and at any time. In support of this new model, this series also: - Makes the debugfs interface optional. - Introduces APIs to unpreserve memory and fixes a bug in the abort path where client state was being incorrectly discarded. Note that this is an interim step, as a more comprehensive fix is planned as part of the stateless KHO work [1]. - Moves all KHO code into a new kernel/liveupdate/ directory to consolidate live update components. This patch (of 9): Currently, KHO is controlled via debugfs interface, but once LUO is introduced, it can control KHO, and the debug interface becomes optional. Add a separate config CONFIG_KEXEC_HANDOVER_DEBUGFS that enables the debugfs interface, and allows to inspect the tree. Move all debugfs related code to a new file to keep the .c files clear of ifdefs. Link: https://lkml.kernel.org/r/20251101142325.1326536-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20251101142325.1326536-2-pasha.tatashin@soleen.com Link: https://lore.kernel.org/all/20251020100306.2709352-1-jasonmiu@google.com [1] Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Changyuan Lyu <changyuanl@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Simon Horman <horms@kernel.org> Cc: Zhu Yanjun <yanjun.zhu@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Stable-dep-of: 019fc3687237 ("kho: fix KASAN support for restored vmalloc regions") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 03d3963464a43654703938a66503cd686c5fc54e ]

Patch series "liveupdate: Rework KHO for in-kernel users", v9.

This series refactors the KHO framework to better support in-kernel users
like the upcoming LUO.  The current design, which relies on a notifier
chain and debugfs for control, is too restrictive for direct programmatic
use.

The core of this rework is the removal of the notifier chain in favor of a
direct registration API.  This decouples clients from the shutdown-time
finalization sequence, allowing them to manage their preserved state more
flexibly and at any time.

In support of this new model, this series also:
 - Makes the debugfs interface optional.
 - Introduces APIs to unpreserve memory and fixes a bug in the abort
   path where client state was being incorrectly discarded. Note that
   this is an interim step, as a more comprehensive fix is planned as
   part of the stateless KHO work [1].
 - Moves all KHO code into a new kernel/liveupdate/ directory to
   consolidate live update components.

This patch (of 9):

Currently, KHO is controlled via debugfs interface, but once LUO is
introduced, it can control KHO, and the debug interface becomes optional.

Add a separate config CONFIG_KEXEC_HANDOVER_DEBUGFS that enables the
debugfs interface, and allows to inspect the tree.

Move all debugfs related code to a new file to keep the .c files clear of
ifdefs.

Link: https://lkml.kernel.org/r/20251101142325.1326536-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20251101142325.1326536-2-pasha.tatashin@soleen.com
Link: https://lore.kernel.org/all/20251020100306.2709352-1-jasonmiu@google.com [1]
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Simon Horman <horms@kernel.org>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 019fc3687237 ("kho: fix KASAN support for restored vmalloc regions")
Signed-off-by: Sasha Levin <sashal@kernel.org>