+ mm-make-memfd_create-into-a-selectable-config-option.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

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The patch titled
     Subject: mm: make MEMFD_CREATE into a selectable config option
has been added to the -mm mm-unstable branch.  Its filename is
     mm-make-memfd_create-into-a-selectable-config-option.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-make-memfd_create-into-a-selectable-config-option.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Thomas Weißschuh <linux@weissschuh.net>
Subject: mm: make MEMFD_CREATE into a selectable config option
Date: Fri, 30 Jun 2023 11:08:53 +0200

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>
---

 fs/Kconfig |    5 ++---
 mm/Kconfig |    3 +++
 2 files changed, 5 insertions(+), 3 deletions(-)

--- a/fs/Kconfig~mm-make-memfd_create-into-a-selectable-config-option
+++ a/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_DEF
 	  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
 
--- a/mm/Kconfig~mm-make-memfd_create-into-a-selectable-config-option
+++ a/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
_

Patches currently in -mm which might be from linux@weissschuh.net are

mm-make-memfd_create-into-a-selectable-config-option.patch