On Fri, Jun 30, 2023 at 11:08:53AM +0200, Thomas Weißschuh wrote: > The memfd_create() syscall, enabled by CONFIG_MEMFD_CREATE, is useful on > its own even when not required by CONFIG_TMPFS or CONFIG_HUGETLBFS. If you don't have tmpfs or hugetlbfs enabled, then what fs ends up backing the file returned by memfd_create()? ramfs? (Not an objection, I'm just curious...) --D > 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. > > Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> > --- > fs/Kconfig | 5 ++--- > mm/Kconfig | 3 +++ > 2 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/fs/Kconfig b/fs/Kconfig > index 18d034ec7953..19975b104bc3 100644 > --- a/fs/Kconfig > +++ b/fs/Kconfig > @@ -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 > > diff --git a/mm/Kconfig b/mm/Kconfig > index 09130434e30d..22acffd9009d 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -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 > > --- > base-commit: e55e5df193d247a38a5e1ac65a5316a0adcc22fa > change-id: 20230629-config-memfd-be6af03b7dca > > Best regards, > -- > Thomas Weißschuh <linux@xxxxxxxxxxxxxx> >
