Issue on compiling the kernel on lesson 7

Hello all,

I'm trying to compile the kernel. I did:

make oldconfig
make -j3 all

But I get the error

GEN security/apparmor/net_names.h
GEN security/apparmor/net_names.h
CC security/apparmor/policy_compat.o
CC security/landlock/domain.o
CC security/integrity/ima/ima_appraise.o
CC security/apparmor/crypto.o
AR security/landlock/built-in.a
CC security/commoncap.o
CC security/integrity/ima/ima_modsig.o
CC security/apparmor/capability.o
CC security/integrity/ima/ima_kexec.o
CC security/lsm_syscalls.o
CC security/integrity/ima/ima_asymmetric_keys.o
CC security/apparmor/resource.o
CC security/integrity/evm/evm_main.o
CC security/integrity/ima/ima_queue_keys.o
CC security/apparmor/net.o
CC security/integrity/ima/ima_efi.o
CC security/integrity/evm/evm_crypto.o
CC security/integrity/ima/ima_iint.o
AR security/apparmor/built-in.a
CC security/min_addr.o
CC security/integrity/evm/evm_secfs.o
AR security/integrity/ima/built-in.a
CC security/integrity/iint.o
CC security/security.o
CC security/integrity/evm/evm_posix_acl.o
CC security/integrity/integrity_audit.o
AR security/integrity/evm/built-in.a
CC security/inode.o
CC security/integrity/digsig.o
CC security/lsm_audit.o
CC security/integrity/digsig_asymmetric.o
CC security/integrity/platform_certs/platform_keyring.o
CC security/device_cgroup.o
CC security/integrity/platform_certs/machine_keyring.o
CC security/integrity/platform_certs/efi_parser.o
CC security/integrity/platform_certs/load_uefi.o
CC security/integrity/platform_certs/keyring_handler.o
AR security/integrity/built-in.a
AR security/built-in.a
make[1]: *** [/linux_work/linux_stable/Makefile:2003: .] Error 2
make: *** [Makefile:248: __sub-make] Error 2
root@kernel-dev:/linux_work/linux_stable#

In the line 2003, the file /linux_work/linux_stable/Makefile

1995 prepare: outputmakefile
1996
1997 # Preset locale variables to speed up the build process. Limit locale
1998 # tweaks to this spot to avoid wrong language settings when running
1999 # make menuconfig etc.
2000 # Error messages still appears in the original language
2001 PHONY += $(build-dir)
2002 $(build-dir): prepare
2003 $(Q)$(MAKE) $(build)=$@ need-builtin=1 need-modorder=1 $(single-goals)
2004
2005 clean-dirs := $(addprefix clean, $(clean-dirs))
2006 PHONY += $(clean-dirs) clean
2007 $(clean-dirs):
2008 $(Q)$(MAKE) $(clean)=$(patsubst clean%,%,$@)
2009
2010 clean: $(clean-dirs)
2011 $(call cmd,rmfiles)
2012 @find . $(RCS_FIND_IGNORE) \
2013 ( -name '.[aios]' -o -name '.rsi' -o -name '.ko' -o -name '..cmd' \
2014 -o -name '.ko.' \
2015 -o -name '.dtb' -o -name '.dtbo' \
2016 -o -name '.dtb.S' -o -name '.dtbo.S' \
2017 -o -name '.dt.yaml' -o -name 'dtbs-list' \
2018 -o -name '.dwo' -o -name '.lst' \
2019 -o -name '.su' -o -name '.mod' \
2020 -o -name '..d' -o -name '..tmp' -o -name '.mod.c' \
2021 -o -name '.lex.c' -o -name '.tab.[ch]' \
2022 -o -name '.asn1.[ch]' \
2023 -o -name '.symtypes' -o -name 'modules.order' \
2024 -o -name '.c.[012].' \
2025 -o -name '.ll' \
2026 -o -name '.gcno' \
2027 ) -type f -print \
2028 -o -name '.tmp_' -print \
2029 | xargs rm -rf

Any idea?