Commit 4496e1c1 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Andrew Morton
Browse files

crash_dump, nvme: select CONFIGFS_FS as built-in 

Configfs can be configured as a loadable module, which causes a link-time
failure for dm-crypt crash dump support:

crash_dump_dm_crypt.c:(.text+0x3a4): undefined reference to `config_item_init_type_name'
aarch64-linux-ld: kernel/crash_dump_dm_crypt.o: in function `configfs_dmcrypt_keys_init':
crash_dump_dm_crypt.c:(.init.text+0x90): undefined reference to `config_group_init'
aarch64-linux-ld: crash_dump_dm_crypt.c:(.init.text+0xb4): undefined reference to `configfs_register_subsystem'
aarch64-linux-ld: crash_dump_dm_crypt.c:(.init.text+0xd8): undefined reference to `configfs_unregister_subsystem'

This could be avoided with a dependency on CONFIGFS_FS=y, but the
dependency has an additional problem of causing Kconfig dependency loops
since most other uses select the symbol.

Using a simple 'select CONFIGFS_FS' here in turn fails with
CONFIG_DM_CRYPT=m, because that still only causes configfs to be a
loadable module.

The only version I found that fixes this reliably uses an additional
Kconfig symbol to ensure the 'select' actually turns on configfs as
builtin, with two additional changes to avoid dependency loops with nvme
and sysfs.

There is no compile-time dependency between configfs and sysfs, so
selecting configfs from a driver with sysfs disabled does not cause link
failures, only the default /sys/kernel/config mount point will not be
created.

Link: https://lkml.kernel.org/r/20250521160359.2132363-1-arnd@kernel.org


Fixes: 6b23858fd63b ("crash_dump: make dm crypt keys persist for the kdump kernel")
Fixes: 1fb47040 ("nvme-loop: add configfs dependency")
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Breno Leitao <leitao@debian.org>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c164679b

drivers/nvme/target/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ 
config NVME_TARGET

	tristate "NVMe Target support"

	depends on BLOCK

	depends on CONFIGFS_FS

	select CONFIGFS_FS

	select NVME_KEYRING if NVME_TARGET_TCP_TLS

	select KEYS if NVME_TARGET_TCP_TLS

	select SGL_ALLOC

fs/configfs/Kconfig

+0 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0-only

config CONFIGFS_FS

	tristate "Userspace-driven configuration filesystem"

	select SYSFS

	help

	  configfs is a RAM-based filesystem that provides the converse

	  of sysfs's functionality. Where sysfs is a filesystem-based

kernel/Kconfig.kexec

+7 −1
Original line number Diff line number Diff line
@@ -120,12 +120,18 @@ config CRASH_DM_CRYPT 
	depends on KEXEC_FILE

	depends on CRASH_DUMP

	depends on DM_CRYPT

	depends on CONFIGFS_FS

	help

	  With this option enabled, user space can intereact with

	  /sys/kernel/config/crash_dm_crypt_keys to make the dm crypt keys

	  persistent for the dump-capture kernel.



config CRASH_DM_CRYPT_CONFIGS

	def_tristate CRASH_DM_CRYPT

	select CONFIGFS_FS

	help

	  CRASH_DM_CRYPT cannot directly select CONFIGFS_FS, because that

	  is required to be built-in.



config CRASH_HOTPLUG

	bool "Update the crash elfcorehdr on system configuration changes"

	default y