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mm: make MEMFD_CREATE into a selectable config option

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The memfd_create() syscall, enabled by CONFIG_MEMFD_CREATE, is useful on
its own even when not required by CONFIG_TMPFS or CONFIG_HUGETLBFS.

Split it into its own proper bool option that can be enabled by users.

Move that option into mm/ where the code itself also lies.  Also add
"select" statements to CONFIG_TMPFS and CONFIG_HUGETLBFS so they
automatically enable CONFIG_MEMFD_CREATE as before.

Link: https://lkml.kernel.org/r/20230630-config-memfd-v1-1-9acc3ae38b5a@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Tested-by: Zhangjin Wu <falcon@tinylab.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Thomas Weißschuh 2023-06-30 11:08:53 +02:00 committed by Andrew Morton
parent fc1878ec70
commit 626e98cb03
2 changed files with 5 additions and 3 deletions
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5
fs/Kconfig
View File

@ -169,6 +169,7 @@ source "fs/sysfs/Kconfig"
config TMPFS
bool "Tmpfs virtual memory file system support (former shm fs)"
depends on SHMEM
select MEMFD_CREATE
help
Tmpfs is a file system which keeps all files in virtual memory.
@ -240,6 +241,7 @@ config HUGETLBFS
bool "HugeTLB file system support"
depends on X86 || IA64 || SPARC64 || ARCH_SUPPORTS_HUGETLBFS || BROKEN
depends on (SYSFS || SYSCTL)
select MEMFD_CREATE
help
hugetlbfs is a filesystem backing for HugeTLB pages, based on
ramfs. For architectures that support it, say Y here and read
@ -264,9 +266,6 @@ config HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON
enable HVO by default. It can be disabled via hugetlb_free_vmemmap=off
(boot command line) or hugetlb_optimize_vmemmap (sysctl).
config MEMFD_CREATE
def_bool TMPFS || HUGETLBFS
config ARCH_HAS_GIGANTIC_PAGE
bool

3
mm/Kconfig
View File

@ -1144,6 +1144,9 @@ config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
config IO_MAPPING
bool
config MEMFD_CREATE
bool "Enable memfd_create() system call" if EXPERT
config SECRETMEM
default y
bool "Enable memfd_secret() system call" if EXPERT