[RFC PATCH 1/2] mm: restrictedmem: Add flag as THP allocation hint for memfd_restricted() syscall
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STALE1332d
From: Ackerley Tng <hidden>
Date: 2023-02-18 00:44:59
Also in:
kvm, linux-arch, linux-doc, linux-fsdevel, linux-mm, lkml, qemu-devel
Subsystem:
memory management, the rest · Maintainers:
Andrew Morton, Linus Torvalds
Allow userspace to hint the kernel to use Transparent HugePages to back restricted memory on a per-file basis. Signed-off-by: Ackerley Tng <redacted> --- include/uapi/linux/restrictedmem.h | 1 + mm/restrictedmem.c | 27 +++++++++++++++++---------- 2 files changed, 18 insertions(+), 10 deletions(-)
diff --git a/include/uapi/linux/restrictedmem.h b/include/uapi/linux/restrictedmem.h
index 9f108dd1ac4c..f671ccbb43bc 100644
--- a/include/uapi/linux/restrictedmem.h
+++ b/include/uapi/linux/restrictedmem.h@@ -4,5 +4,6 @@ /* flags for memfd_restricted */ #define RMFD_TMPFILE 0x0001U +#define RMFD_HUGEPAGE 0x0002U #endif /* _UAPI_LINUX_RESTRICTEDMEM_H */
diff --git a/mm/restrictedmem.c b/mm/restrictedmem.c
index 97f3e2159e8b..87c829960b31 100644
--- a/mm/restrictedmem.c
+++ b/mm/restrictedmem.c@@ -190,19 +190,25 @@ static struct file *restrictedmem_file_create(struct file *memfd) return file; } -static int restrictedmem_create(struct vfsmount *mount) +static int restrictedmem_create(unsigned int flags, struct vfsmount *mount) { struct file *file, *restricted_file; int fd, err; + unsigned long shmem_setup_flags = VM_NORESERVE; fd = get_unused_fd_flags(0); if (fd < 0) return fd; - if (mount) - file = shmem_file_setup_with_mnt(mount, "memfd:restrictedmem", 0, VM_NORESERVE); - else - file = shmem_file_setup("memfd:restrictedmem", 0, VM_NORESERVE); + if (flags & RMFD_HUGEPAGE) + shmem_setup_flags |= VM_HUGEPAGE; + + if (mount) { + file = shmem_file_setup_with_mnt(mount, "memfd:restrictedmem", + 0, shmem_setup_flags); + } else { + file = shmem_file_setup("memfd:restrictedmem", 0, shmem_setup_flags); + } if (IS_ERR(file)) { err = PTR_ERR(file);
@@ -230,7 +236,8 @@ static bool is_shmem_mount(struct vfsmount *mnt) return mnt->mnt_sb->s_magic == TMPFS_MAGIC; } -static int restrictedmem_create_from_path(const char __user *mount_path) +static int restrictedmem_create_from_path(unsigned int flags, + const char __user *mount_path) { int ret; struct path path;
@@ -250,7 +257,7 @@ static int restrictedmem_create_from_path(const char __user *mount_path) if (unlikely(ret)) goto out; - ret = restrictedmem_create(path.mnt); + ret = restrictedmem_create(flags, path.mnt); mnt_drop_write(path.mnt); out:
@@ -261,16 +268,16 @@ static int restrictedmem_create_from_path(const char __user *mount_path) SYSCALL_DEFINE2(memfd_restricted, unsigned int, flags, const char __user *, mount_path) { - if (flags & ~RMFD_TMPFILE) + if (flags & ~(RMFD_TMPFILE | RMFD_HUGEPAGE)) return -EINVAL; if (flags == RMFD_TMPFILE) { if (!mount_path) return -EINVAL; - return restrictedmem_create_from_path(mount_path); + return restrictedmem_create_from_path(flags, mount_path); } else { - return restrictedmem_create(NULL); + return restrictedmem_create(flags, NULL); } }
--
2.39.2.637.g21b0678d19-goog