[PATCH 0/2] Add hugetlbfs support to memfd_create()

[PATCH 0/2] Add hugetlbfs support to memfd_create()

[Mike Kravetz]

This is a resend of the patch sent in the RFC:
http://lkml.kernel.org/r/1502149672-7759-1-git-send-email-mike.kravetz@oracle.com

It addresses the issues with the commit message raised by Michal Hocko.
Only the commit message is modified, the code from the RFC patch is the
same.

In addition, a new patch is included to modify the memfd selftest.  The
modifications allow basic functionality testing of memfd_create with
hugetlbfs.

Mike Kravetz (2):
  mm/shmem: add hugetlbfs support to memfd_create()
  selftests/memfd: Add memfd_create hugetlbfs selftest

 include/uapi/linux/memfd.h                 |  24 ++
 mm/shmem.c                                 |  37 ++-
 tools/testing/selftests/memfd/Makefile     |   2 +-
 tools/testing/selftests/memfd/memfd_test.c | 372 ++++++++++++++++++++++-------
 tools/testing/selftests/memfd/run_tests.sh |  69 ++++++
 5 files changed, 412 insertions(+), 92 deletions(-)
 create mode 100755 tools/testing/selftests/memfd/run_tests.sh

-- 
2.7.5

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[PATCH 1/2] mm/shmem: add hugetlbfs support to memfd_create()

[Mike Kravetz]

This patch came out of discussions in this e-mail thread:
http://lkml.kernel.org/r/1499357846-7481-1-git-send-email-mike.kravetz%40oracle.com

The Oracle JVM team is developing a new garbage collection model.  This
new model requires multiple mappings of the same anonymous memory.  One
straight forward way to accomplish this is with memfd_create.  They can
use the returned fd to create multiple mappings of the same memory.

The JVM today has an option to use (static hugetlb) huge pages.  If this
option is specified, they would like to use the same garbage collection
model requiring multiple mappings to the same memory.  Using hugetlbfs,
it is possible to explicitly mount a filesystem and specify file paths
in order to get an fd that can be used for multiple mappings.  However,
this introduces additional system admin work and coordination.

Ideally they would like to get a hugetlbfs fd without requiring explicit
mounting of a filesystem.   Today, mmap and shmget can make use of
hugetlbfs without explicitly mounting a filesystem.  The patch adds this
functionality to memfd_create.

Add a new flag MFD_HUGETLB to memfd_create() that will specify the
file to be created resides in the hugetlbfs filesystem.  This is
the generic hugetlbfs filesystem not associated with any specific
mount point.  As with other system calls that request hugetlbfs
backed pages, there is the ability to encode huge page size in the
flag arguments.

hugetlbfs does not support sealing operations, therefore specifying
MFD_ALLOW_SEALING with MFD_HUGETLB will result in EINVAL.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 include/uapi/linux/memfd.h | 24 ++++++++++++++++++++++++
 mm/shmem.c                 | 37 +++++++++++++++++++++++++++++++------
 2 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/memfd.h b/include/uapi/linux/memfd.h
index 534e364..7f3a722 100644
--- a/include/uapi/linux/memfd.h
+++ b/include/uapi/linux/memfd.h
@@ -1,8 +1,32 @@
 #ifndef _UAPI_LINUX_MEMFD_H
 #define _UAPI_LINUX_MEMFD_H
 
+#include <asm-generic/hugetlb_encode.h>
+
 /* flags for memfd_create(2) (unsigned int) */
 #define MFD_CLOEXEC		0x0001U
 #define MFD_ALLOW_SEALING	0x0002U
+#define MFD_HUGETLB		0x0004U
+
+/*
+ * Huge page size encoding when MFD_HUGETLB is specified, and a huge page
+ * size other than the default is desired.  See hugetlb_encode.h.
+ * All known huge page size encodings are provided here.  It is the
+ * responsibility of the application to know which sizes are supported on
+ * the running system.  See mmap(2) man page for details.
+ */
+#define MFD_HUGE_SHIFT	HUGETLB_FLAG_ENCODE_SHIFT
+#define MFD_HUGE_MASK	HUGETLB_FLAG_ENCODE_MASK
+
+#define MFD_HUGE_64KB	HUGETLB_FLAG_ENCODE_64KB
+#define MFD_HUGE_512KB	HUGETLB_FLAG_ENCODE_512KB
+#define MFD_HUGE_1MB	HUGETLB_FLAG_ENCODE_1MB
+#define MFD_HUGE_2MB	HUGETLB_FLAG_ENCODE_2MB
+#define MFD_HUGE_8MB	HUGETLB_FLAG_ENCODE_8MB
+#define MFD_HUGE_16MB	HUGETLB_FLAG_ENCODE_16MB
+#define MFD_HUGE_256MB	HUGETLB_FLAG_ENCODE_256MB
+#define MFD_HUGE_1GB	HUGETLB_FLAG_ENCODE_1GB
+#define MFD_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB
+#define MFD_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB
 
 #endif /* _UAPI_LINUX_MEMFD_H */
diff --git a/mm/shmem.c b/mm/shmem.c
index b0aa607..3db79ce 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -34,6 +34,7 @@
 #include <linux/swap.h>
 #include <linux/uio.h>
 #include <linux/khugepaged.h>
+#include <linux/hugetlb.h>
 
 #include <asm/tlbflush.h> /* for arch/microblaze update_mmu_cache() */
 
@@ -3627,7 +3628,7 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
 #define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
 #define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
 
-#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
+#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB)
 
 SYSCALL_DEFINE2(memfd_create,
 		const char __user *, uname,
@@ -3639,8 +3640,18 @@ SYSCALL_DEFINE2(memfd_create,
 	char *name;
 	long len;
 
-	if (flags & ~(unsigned int)MFD_ALL_FLAGS)
-		return -EINVAL;
+	if (!(flags & MFD_HUGETLB)) {
+		if (flags & ~(unsigned int)MFD_ALL_FLAGS)
+			return -EINVAL;
+	} else {
+		/* Sealing not supported in hugetlbfs (MFD_HUGETLB) */
+		if (flags & MFD_ALLOW_SEALING)
+			return -EINVAL;
+		/* Allow huge page size encoding in flags. */
+		if (flags & ~(unsigned int)(MFD_ALL_FLAGS |
+				(MFD_HUGE_MASK << MFD_HUGE_SHIFT)))
+			return -EINVAL;
+	}
 
 	/* length includes terminating zero */
 	len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
@@ -3671,16 +3682,30 @@ SYSCALL_DEFINE2(memfd_create,
 		goto err_name;
 	}
 
-	file = shmem_file_setup(name, 0, VM_NORESERVE);
+	if (flags & MFD_HUGETLB) {
+		struct user_struct *user = NULL;
+
+		file = hugetlb_file_setup(name, 0, VM_NORESERVE, &user,
+					HUGETLB_ANONHUGE_INODE,
+					(flags >> MFD_HUGE_SHIFT) &
+					MFD_HUGE_MASK);
+	} else
+		file = shmem_file_setup(name, 0, VM_NORESERVE);
 	if (IS_ERR(file)) {
 		error = PTR_ERR(file);
 		goto err_fd;
 	}
-	info = SHMEM_I(file_inode(file));
 	file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
 	file->f_flags |= O_RDWR | O_LARGEFILE;
-	if (flags & MFD_ALLOW_SEALING)
+
+	if (flags & MFD_ALLOW_SEALING) {
+		/*
+		 * flags check at beginning of function ensures
+		 * this is not a hugetlbfs (MFD_HUGETLB) file.
+		 */
+		info = SHMEM_I(file_inode(file));
 		info->seals &= ~F_SEAL_SEAL;
+	}
 
 	fd_install(fd, file);
 	kfree(name);
-- 
2.7.5

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[PATCH 2/2] selftests/memfd: Add memfd_create hugetlbfs selftest

[Mike Kravetz]

With the addition of hugetlbfs support in memfd_create, the memfd
selftests should verify correct functionality with hugetlbfs.

Instead of writing a separate memfd hugetlbfs test, modify the
memfd_test program to take an optional argument 'hugetlbfs'.  If
the hugetlbfs argument is specified, basic memfd_create functionality
will be exercised on hugetlbfs.  If hugetlbfs is not specified, the
current functionality of the test is unchanged.

Note that many of the tests in memfd_test test file sealing operations.
hugetlbfs does not support file sealing, therefore for hugetlbfs all
sealing related tests are skipped.

In order to test on hugetlbfs, there needs to be preallocated huge pages.
A new script (run_tests) is added.  This script will first run the
existing memfd_create tests.  It will then, attempt to allocate the
required number of huge pages before running the hugetlbfs test.  At
the end of testing, it will release any huge pages allocated for testing
purposes.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 tools/testing/selftests/memfd/Makefile     |   2 +-
 tools/testing/selftests/memfd/memfd_test.c | 372 ++++++++++++++++++++++-------
 tools/testing/selftests/memfd/run_tests.sh |  69 ++++++
 3 files changed, 357 insertions(+), 86 deletions(-)
 create mode 100755 tools/testing/selftests/memfd/run_tests.sh

diff --git a/tools/testing/selftests/memfd/Makefile b/tools/testing/selftests/memfd/Makefile
index ad8a089..bc9d02d 100644
--- a/tools/testing/selftests/memfd/Makefile
+++ b/tools/testing/selftests/memfd/Makefile
@@ -3,7 +3,7 @@ CFLAGS += -I../../../../include/uapi/
 CFLAGS += -I../../../../include/
 CFLAGS += -I../../../../usr/include/
 
-TEST_PROGS := run_fuse_test.sh
+TEST_PROGS := run_tests.sh
 TEST_GEN_FILES := memfd_test fuse_mnt fuse_test
 
 fuse_mnt.o: CFLAGS += $(shell pkg-config fuse --cflags)
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index 2654689..f94c6d1 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -18,12 +18,48 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+#define MEMFD_STR	"memfd:"
+#define SHARED_FT_STR	"(shared file-table)"
+
 #define MFD_DEF_SIZE 8192
 #define STACK_SIZE 65536
 
+/*
+ * Default is not to test hugetlbfs
+ */
+static int hugetlbfs_test;
+static size_t mfd_def_size = MFD_DEF_SIZE;
+
+/*
+ * Copied from mlock2-tests.c
+ */
+static unsigned long default_huge_page_size(void)
+{
+	unsigned long hps = 0;
+	char *line = NULL;
+	size_t linelen = 0;
+	FILE *f = fopen("/proc/meminfo", "r");
+
+	if (!f)
+		return 0;
+	while (getline(&line, &linelen, f) > 0) {
+		if (sscanf(line, "Hugepagesize:       %lu kB", &hps) == 1) {
+			hps <<= 10;
+			break;
+		}
+	}
+
+	free(line);
+	fclose(f);
+	return hps;
+}
+
 static int sys_memfd_create(const char *name,
 			    unsigned int flags)
 {
+	if (hugetlbfs_test)
+		flags |= MFD_HUGETLB;
+
 	return syscall(__NR_memfd_create, name, flags);
 }
 
@@ -150,7 +186,7 @@ static void *mfd_assert_mmap_shared(int fd)
 	void *p;
 
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_READ | PROT_WRITE,
 		 MAP_SHARED,
 		 fd,
@@ -168,7 +204,7 @@ static void *mfd_assert_mmap_private(int fd)
 	void *p;
 
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_READ,
 		 MAP_PRIVATE,
 		 fd,
@@ -223,7 +259,7 @@ static void mfd_assert_read(int fd)
 
 	/* verify PROT_READ *is* allowed */
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_READ,
 		 MAP_PRIVATE,
 		 fd,
@@ -232,11 +268,11 @@ static void mfd_assert_read(int fd)
 		printf("mmap() failed: %m\n");
 		abort();
 	}
-	munmap(p, MFD_DEF_SIZE);
+	munmap(p, mfd_def_size);
 
 	/* verify MAP_PRIVATE is *always* allowed (even writable) */
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_READ | PROT_WRITE,
 		 MAP_PRIVATE,
 		 fd,
@@ -245,7 +281,7 @@ static void mfd_assert_read(int fd)
 		printf("mmap() failed: %m\n");
 		abort();
 	}
-	munmap(p, MFD_DEF_SIZE);
+	munmap(p, mfd_def_size);
 }
 
 static void mfd_assert_write(int fd)
@@ -254,16 +290,22 @@ static void mfd_assert_write(int fd)
 	void *p;
 	int r;
 
-	/* verify write() succeeds */
-	l = write(fd, "\0\0\0\0", 4);
-	if (l != 4) {
-		printf("write() failed: %m\n");
-		abort();
+	/*
+	 * huegtlbfs does not support write, but we want to
+	 * verify everything else here.
+	 */
+	if (!hugetlbfs_test) {
+		/* verify write() succeeds */
+		l = write(fd, "\0\0\0\0", 4);
+		if (l != 4) {
+			printf("write() failed: %m\n");
+			abort();
+		}
 	}
 
 	/* verify PROT_READ | PROT_WRITE is allowed */
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_READ | PROT_WRITE,
 		 MAP_SHARED,
 		 fd,
@@ -273,11 +315,11 @@ static void mfd_assert_write(int fd)
 		abort();
 	}
 	*(char *)p = 0;
-	munmap(p, MFD_DEF_SIZE);
+	munmap(p, mfd_def_size);
 
 	/* verify PROT_WRITE is allowed */
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_WRITE,
 		 MAP_SHARED,
 		 fd,
@@ -287,12 +329,12 @@ static void mfd_assert_write(int fd)
 		abort();
 	}
 	*(char *)p = 0;
-	munmap(p, MFD_DEF_SIZE);
+	munmap(p, mfd_def_size);
 
 	/* verify PROT_READ with MAP_SHARED is allowed and a following
 	 * mprotect(PROT_WRITE) allows writing */
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_READ,
 		 MAP_SHARED,
 		 fd,
@@ -302,20 +344,20 @@ static void mfd_assert_write(int fd)
 		abort();
 	}
 
-	r = mprotect(p, MFD_DEF_SIZE, PROT_READ | PROT_WRITE);
+	r = mprotect(p, mfd_def_size, PROT_READ | PROT_WRITE);
 	if (r < 0) {
 		printf("mprotect() failed: %m\n");
 		abort();
 	}
 
 	*(char *)p = 0;
-	munmap(p, MFD_DEF_SIZE);
+	munmap(p, mfd_def_size);
 
 	/* verify PUNCH_HOLE works */
 	r = fallocate(fd,
 		      FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 		      0,
-		      MFD_DEF_SIZE);
+		      mfd_def_size);
 	if (r < 0) {
 		printf("fallocate(PUNCH_HOLE) failed: %m\n");
 		abort();
@@ -337,7 +379,7 @@ static void mfd_fail_write(int fd)
 
 	/* verify PROT_READ | PROT_WRITE is not allowed */
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_READ | PROT_WRITE,
 		 MAP_SHARED,
 		 fd,
@@ -349,7 +391,7 @@ static void mfd_fail_write(int fd)
 
 	/* verify PROT_WRITE is not allowed */
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_WRITE,
 		 MAP_SHARED,
 		 fd,
@@ -362,13 +404,13 @@ static void mfd_fail_write(int fd)
 	/* Verify PROT_READ with MAP_SHARED with a following mprotect is not
 	 * allowed. Note that for r/w the kernel already prevents the mmap. */
 	p = mmap(NULL,
-		 MFD_DEF_SIZE,
+		 mfd_def_size,
 		 PROT_READ,
 		 MAP_SHARED,
 		 fd,
 		 0);
 	if (p != MAP_FAILED) {
-		r = mprotect(p, MFD_DEF_SIZE, PROT_READ | PROT_WRITE);
+		r = mprotect(p, mfd_def_size, PROT_READ | PROT_WRITE);
 		if (r >= 0) {
 			printf("mmap()+mprotect() didn't fail as expected\n");
 			abort();
@@ -379,7 +421,7 @@ static void mfd_fail_write(int fd)
 	r = fallocate(fd,
 		      FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 		      0,
-		      MFD_DEF_SIZE);
+		      mfd_def_size);
 	if (r >= 0) {
 		printf("fallocate(PUNCH_HOLE) didn't fail as expected\n");
 		abort();
@@ -390,13 +432,13 @@ static void mfd_assert_shrink(int fd)
 {
 	int r, fd2;
 
-	r = ftruncate(fd, MFD_DEF_SIZE / 2);
+	r = ftruncate(fd, mfd_def_size / 2);
 	if (r < 0) {
 		printf("ftruncate(SHRINK) failed: %m\n");
 		abort();
 	}
 
-	mfd_assert_size(fd, MFD_DEF_SIZE / 2);
+	mfd_assert_size(fd, mfd_def_size / 2);
 
 	fd2 = mfd_assert_open(fd,
 			      O_RDWR | O_CREAT | O_TRUNC,
@@ -410,7 +452,7 @@ static void mfd_fail_shrink(int fd)
 {
 	int r;
 
-	r = ftruncate(fd, MFD_DEF_SIZE / 2);
+	r = ftruncate(fd, mfd_def_size / 2);
 	if (r >= 0) {
 		printf("ftruncate(SHRINK) didn't fail as expected\n");
 		abort();
@@ -425,31 +467,31 @@ static void mfd_assert_grow(int fd)
 {
 	int r;
 
-	r = ftruncate(fd, MFD_DEF_SIZE * 2);
+	r = ftruncate(fd, mfd_def_size * 2);
 	if (r < 0) {
 		printf("ftruncate(GROW) failed: %m\n");
 		abort();
 	}
 
-	mfd_assert_size(fd, MFD_DEF_SIZE * 2);
+	mfd_assert_size(fd, mfd_def_size * 2);
 
 	r = fallocate(fd,
 		      0,
 		      0,
-		      MFD_DEF_SIZE * 4);
+		      mfd_def_size * 4);
 	if (r < 0) {
 		printf("fallocate(ALLOC) failed: %m\n");
 		abort();
 	}
 
-	mfd_assert_size(fd, MFD_DEF_SIZE * 4);
+	mfd_assert_size(fd, mfd_def_size * 4);
 }
 
 static void mfd_fail_grow(int fd)
 {
 	int r;
 
-	r = ftruncate(fd, MFD_DEF_SIZE * 2);
+	r = ftruncate(fd, mfd_def_size * 2);
 	if (r >= 0) {
 		printf("ftruncate(GROW) didn't fail as expected\n");
 		abort();
@@ -458,7 +500,7 @@ static void mfd_fail_grow(int fd)
 	r = fallocate(fd,
 		      0,
 		      0,
-		      MFD_DEF_SIZE * 4);
+		      mfd_def_size * 4);
 	if (r >= 0) {
 		printf("fallocate(ALLOC) didn't fail as expected\n");
 		abort();
@@ -467,25 +509,37 @@ static void mfd_fail_grow(int fd)
 
 static void mfd_assert_grow_write(int fd)
 {
-	static char buf[MFD_DEF_SIZE * 8];
+	static char *buf;
 	ssize_t l;
 
-	l = pwrite(fd, buf, sizeof(buf), 0);
-	if (l != sizeof(buf)) {
+	buf = malloc(mfd_def_size * 8);
+	if (!buf) {
+		printf("malloc(%d) failed: %m\n", mfd_def_size * 8);
+		abort();
+	}
+
+	l = pwrite(fd, buf, mfd_def_size * 8, 0);
+	if (l != (mfd_def_size * 8)) {
 		printf("pwrite() failed: %m\n");
 		abort();
 	}
 
-	mfd_assert_size(fd, MFD_DEF_SIZE * 8);
+	mfd_assert_size(fd, mfd_def_size * 8);
 }
 
 static void mfd_fail_grow_write(int fd)
 {
-	static char buf[MFD_DEF_SIZE * 8];
+	static char *buf;
 	ssize_t l;
 
-	l = pwrite(fd, buf, sizeof(buf), 0);
-	if (l == sizeof(buf)) {
+	buf = malloc(mfd_def_size * 8);
+	if (!buf) {
+		printf("malloc(%d) failed: %m\n", mfd_def_size * 8);
+		abort();
+	}
+
+	l = pwrite(fd, buf, mfd_def_size * 8, 0);
+	if (l == (mfd_def_size * 8)) {
 		printf("pwrite() didn't fail as expected\n");
 		abort();
 	}
@@ -543,6 +597,8 @@ static void test_create(void)
 	char buf[2048];
 	int fd;
 
+	printf("%s CREATE\n", MEMFD_STR);
+
 	/* test NULL name */
 	mfd_fail_new(NULL, 0);
 
@@ -570,13 +626,18 @@ static void test_create(void)
 	fd = mfd_assert_new("", 0, MFD_CLOEXEC);
 	close(fd);
 
-	/* verify MFD_ALLOW_SEALING is allowed */
-	fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING);
-	close(fd);
-
-	/* verify MFD_ALLOW_SEALING | MFD_CLOEXEC is allowed */
-	fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING | MFD_CLOEXEC);
-	close(fd);
+	if (!hugetlbfs_test) {
+		/* verify MFD_ALLOW_SEALING is allowed */
+		fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING);
+		close(fd);
+
+		/* verify MFD_ALLOW_SEALING | MFD_CLOEXEC is allowed */
+		fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING | MFD_CLOEXEC);
+		close(fd);
+	} else {
+		/* sealing is not supported on hugetlbfs */
+		mfd_fail_new("", MFD_ALLOW_SEALING);
+	}
 }
 
 /*
@@ -587,8 +648,14 @@ static void test_basic(void)
 {
 	int fd;
 
+	/* hugetlbfs does not contain sealing support */
+	if (hugetlbfs_test)
+		return;
+
+	printf("%s BASIC\n", MEMFD_STR);
+
 	fd = mfd_assert_new("kern_memfd_basic",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 
 	/* add basic seals */
@@ -619,7 +686,7 @@ static void test_basic(void)
 
 	/* verify sealing does not work without MFD_ALLOW_SEALING */
 	fd = mfd_assert_new("kern_memfd_basic",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC);
 	mfd_assert_has_seals(fd, F_SEAL_SEAL);
 	mfd_fail_add_seals(fd, F_SEAL_SHRINK |
@@ -630,6 +697,28 @@ static void test_basic(void)
 }
 
 /*
+ * hugetlbfs doesn't support seals or write, so just verify grow and shrink
+ * on a hugetlbfs file created via memfd_create.
+ */
+static void test_hugetlbfs_grow_shrink(void)
+{
+	int fd;
+
+	printf("%s HUGETLBFS-GROW-SHRINK\n", MEMFD_STR);
+
+	fd = mfd_assert_new("kern_memfd_seal_write",
+			    mfd_def_size,
+			    MFD_CLOEXEC);
+
+	mfd_assert_read(fd);
+	mfd_assert_write(fd);
+	mfd_assert_shrink(fd);
+	mfd_assert_grow(fd);
+
+	close(fd);
+}
+
+/*
  * Test SEAL_WRITE
  * Test whether SEAL_WRITE actually prevents modifications.
  */
@@ -637,8 +726,17 @@ static void test_seal_write(void)
 {
 	int fd;
 
+	/*
+	 * hugetlbfs does not contain sealing or write support.  Just test
+	 * basic grow and shrink via test_hugetlbfs_grow_shrink.
+	 */
+	if (hugetlbfs_test)
+		return test_hugetlbfs_grow_shrink();
+
+	printf("%s SEAL-WRITE\n", MEMFD_STR);
+
 	fd = mfd_assert_new("kern_memfd_seal_write",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 	mfd_assert_has_seals(fd, 0);
 	mfd_assert_add_seals(fd, F_SEAL_WRITE);
@@ -661,8 +759,14 @@ static void test_seal_shrink(void)
 {
 	int fd;
 
+	/* hugetlbfs does not contain sealing support */
+	if (hugetlbfs_test)
+		return;
+
+	printf("%s SEAL-SHRINK\n", MEMFD_STR);
+
 	fd = mfd_assert_new("kern_memfd_seal_shrink",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 	mfd_assert_has_seals(fd, 0);
 	mfd_assert_add_seals(fd, F_SEAL_SHRINK);
@@ -685,8 +789,14 @@ static void test_seal_grow(void)
 {
 	int fd;
 
+	/* hugetlbfs does not contain sealing support */
+	if (hugetlbfs_test)
+		return;
+
+	printf("%s SEAL-GROW\n", MEMFD_STR);
+
 	fd = mfd_assert_new("kern_memfd_seal_grow",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 	mfd_assert_has_seals(fd, 0);
 	mfd_assert_add_seals(fd, F_SEAL_GROW);
@@ -709,8 +819,14 @@ static void test_seal_resize(void)
 {
 	int fd;
 
+	/* hugetlbfs does not contain sealing support */
+	if (hugetlbfs_test)
+		return;
+
+	printf("%s SEAL-RESIZE\n", MEMFD_STR);
+
 	fd = mfd_assert_new("kern_memfd_seal_resize",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 	mfd_assert_has_seals(fd, 0);
 	mfd_assert_add_seals(fd, F_SEAL_SHRINK | F_SEAL_GROW);
@@ -726,15 +842,52 @@ static void test_seal_resize(void)
 }
 
 /*
+ * hugetlbfs does not support seals.  Basic test to dup the memfd created
+ * fd and perform some basic operations on it.
+ */
+static void hugetlbfs_dup(char *b_suffix)
+{
+	int fd, fd2;
+
+	printf("%s HUGETLBFS-DUP %s\n", MEMFD_STR, b_suffix);
+
+	fd = mfd_assert_new("kern_memfd_share_dup",
+			    mfd_def_size,
+			    MFD_CLOEXEC);
+
+	fd2 = mfd_assert_dup(fd);
+
+	mfd_assert_read(fd);
+	mfd_assert_write(fd);
+
+	mfd_assert_shrink(fd2);
+	mfd_assert_grow(fd2);
+
+	close(fd2);
+	close(fd);
+}
+
+/*
  * Test sharing via dup()
  * Test that seals are shared between dupped FDs and they're all equal.
  */
-static void test_share_dup(void)
+static void test_share_dup(char *banner, char *b_suffix)
 {
 	int fd, fd2;
 
+	/*
+	 * hugetlbfs does not contain sealing support.  Perform some
+	 * basic testing on dup'ed fd instead via hugetlbfs_dup.
+	 */
+	if (hugetlbfs_test) {
+		hugetlbfs_dup(b_suffix);
+		return;
+	}
+
+	printf("%s %s %s\n", MEMFD_STR, banner, b_suffix);
+
 	fd = mfd_assert_new("kern_memfd_share_dup",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 	mfd_assert_has_seals(fd, 0);
 
@@ -768,13 +921,19 @@ static void test_share_dup(void)
  * Test sealing with active mmap()s
  * Modifying seals is only allowed if no other mmap() refs exist.
  */
-static void test_share_mmap(void)
+static void test_share_mmap(char *banner, char *b_suffix)
 {
 	int fd;
 	void *p;
 
+	/* hugetlbfs does not contain sealing support */
+	if (hugetlbfs_test)
+		return;
+
+	printf("%s %s %s\n", MEMFD_STR,  banner, b_suffix);
+
 	fd = mfd_assert_new("kern_memfd_share_mmap",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 	mfd_assert_has_seals(fd, 0);
 
@@ -784,14 +943,40 @@ static void test_share_mmap(void)
 	mfd_assert_has_seals(fd, 0);
 	mfd_assert_add_seals(fd, F_SEAL_SHRINK);
 	mfd_assert_has_seals(fd, F_SEAL_SHRINK);
-	munmap(p, MFD_DEF_SIZE);
+	munmap(p, mfd_def_size);
 
 	/* readable ref allows sealing */
 	p = mfd_assert_mmap_private(fd);
 	mfd_assert_add_seals(fd, F_SEAL_WRITE);
 	mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
-	munmap(p, MFD_DEF_SIZE);
+	munmap(p, mfd_def_size);
+
+	close(fd);
+}
+
+/*
+ * Basic test to make sure we can open the hugetlbfs fd via /proc and
+ * perform some simple operations on it.
+ */
+static void hugetlbfs_proc_open(char *b_suffix)
+{
+	int fd, fd2;
+
+	printf("%s HUGETLBFS-PROC-OPEN %s\n", MEMFD_STR, b_suffix);
 
+	fd = mfd_assert_new("kern_memfd_share_open",
+			    mfd_def_size,
+			    MFD_CLOEXEC);
+
+	fd2 = mfd_assert_open(fd, O_RDWR, 0);
+
+	mfd_assert_read(fd);
+	mfd_assert_write(fd);
+
+	mfd_assert_shrink(fd2);
+	mfd_assert_grow(fd2);
+
+	close(fd2);
 	close(fd);
 }
 
@@ -801,12 +986,23 @@ static void test_share_mmap(void)
  * This is *not* like dup(), but like a real separate open(). Make sure the
  * semantics are as expected and we correctly check for RDONLY / WRONLY / RDWR.
  */
-static void test_share_open(void)
+static void test_share_open(char *banner, char *b_suffix)
 {
 	int fd, fd2;
 
+	/*
+	 * hugetlbfs does not contain sealing support.  So test basic
+	 * functionality of using /proc fd via hugetlbfs_proc_open
+	 */
+	if (hugetlbfs_test) {
+		hugetlbfs_proc_open(b_suffix);
+		return;
+	}
+
+	printf("%s %s %s\n", MEMFD_STR, banner, b_suffix);
+
 	fd = mfd_assert_new("kern_memfd_share_open",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 	mfd_assert_has_seals(fd, 0);
 
@@ -841,13 +1037,19 @@ static void test_share_open(void)
  * Test sharing via fork()
  * Test whether seal-modifications work as expected with forked childs.
  */
-static void test_share_fork(void)
+static void test_share_fork(char *banner, char *b_suffix)
 {
 	int fd;
 	pid_t pid;
 
+	/* hugetlbfs does not contain sealing support */
+	if (hugetlbfs_test)
+		return;
+
+	printf("%s %s %s\n", MEMFD_STR, banner, b_suffix);
+
 	fd = mfd_assert_new("kern_memfd_share_fork",
-			    MFD_DEF_SIZE,
+			    mfd_def_size,
 			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
 	mfd_assert_has_seals(fd, 0);
 
@@ -870,40 +1072,40 @@ int main(int argc, char **argv)
 {
 	pid_t pid;
 
-	printf("memfd: CREATE\n");
+	if (argc == 2) {
+		if (!strcmp(argv[1], "hugetlbfs")) {
+			unsigned long hpage_size = default_huge_page_size();
+
+			if (!hpage_size) {
+				printf("Unable to determine huge page size\n");
+				abort();
+			}
+
+			hugetlbfs_test = 1;
+			mfd_def_size = hpage_size * 2;
+		}
+	}
+
 	test_create();
-	printf("memfd: BASIC\n");
 	test_basic();
 
-	printf("memfd: SEAL-WRITE\n");
 	test_seal_write();
-	printf("memfd: SEAL-SHRINK\n");
 	test_seal_shrink();
-	printf("memfd: SEAL-GROW\n");
 	test_seal_grow();
-	printf("memfd: SEAL-RESIZE\n");
 	test_seal_resize();
 
-	printf("memfd: SHARE-DUP\n");
-	test_share_dup();
-	printf("memfd: SHARE-MMAP\n");
-	test_share_mmap();
-	printf("memfd: SHARE-OPEN\n");
-	test_share_open();
-	printf("memfd: SHARE-FORK\n");
-	test_share_fork();
+	test_share_dup("SHARE-DUP", "");
+	test_share_mmap("SHARE-MMAP", "");
+	test_share_open("SHARE-OPEN", "");
+	test_share_fork("SHARE-FORK", "");
 
 	/* Run test-suite in a multi-threaded environment with a shared
 	 * file-table. */
 	pid = spawn_idle_thread(CLONE_FILES | CLONE_FS | CLONE_VM);
-	printf("memfd: SHARE-DUP (shared file-table)\n");
-	test_share_dup();
-	printf("memfd: SHARE-MMAP (shared file-table)\n");
-	test_share_mmap();
-	printf("memfd: SHARE-OPEN (shared file-table)\n");
-	test_share_open();
-	printf("memfd: SHARE-FORK (shared file-table)\n");
-	test_share_fork();
+	test_share_dup("SHARE-DUP", SHARED_FT_STR);
+	test_share_mmap("SHARE-MMAP", SHARED_FT_STR);
+	test_share_open("SHARE-OPEN", SHARED_FT_STR);
+	test_share_fork("SHARE-FORK", SHARED_FT_STR);
 	join_idle_thread(pid);
 
 	printf("memfd: DONE\n");
diff --git a/tools/testing/selftests/memfd/run_tests.sh b/tools/testing/selftests/memfd/run_tests.sh
new file mode 100755
index 0000000..daabb35
--- /dev/null
+++ b/tools/testing/selftests/memfd/run_tests.sh
@@ -0,0 +1,69 @@
+#!/bin/bash
+# please run as root
+
+#
+# Normal tests requiring no special resources
+#
+./run_fuse_test.sh
+./memfd_test
+
+#
+# To test memfd_create with hugetlbfs, there needs to be hpages_test
+# huge pages free.  Attempt to allocate enough pages to test.
+#
+hpages_test=8
+
+#
+# Get count of free huge pages from /proc/meminfo
+#
+while read name size unit; do
+        if [ "$name" = "HugePages_Free:" ]; then
+                freepgs=$size
+        fi
+done < /proc/meminfo
+
+#
+# If not enough free huge pages for test, attempt to increase
+#
+if [ -n "$freepgs" ] && [ $freepgs -lt $hpages_test ]; then
+	nr_hugepgs=`cat /proc/sys/vm/nr_hugepages`
+	hpages_needed=`expr $hpages_test - $freepgs`
+
+	echo 3 > /proc/sys/vm/drop_caches
+	echo $(( $hpages_needed + $nr_hugepgs )) > /proc/sys/vm/nr_hugepages
+	if [ $? -ne 0 ]; then
+		echo "Please run this test as root"
+		exit 1
+	fi
+	while read name size unit; do
+		if [ "$name" = "HugePages_Free:" ]; then
+			freepgs=$size
+		fi
+	done < /proc/meminfo
+fi
+
+#
+# If still not enough huge pages available, exit.  But, give back any huge
+# pages potentially allocated above.
+#
+if [ $freepgs -lt $hpages_test ]; then
+	# nr_hugepgs non-zero only if we attempted to increase
+	if [ -n "$nr_hugepgs" ]; then
+		echo $nr_hugepgs > /proc/sys/vm/nr_hugepages
+	fi
+	printf "Not enough huge pages available (%d < %d)\n" \
+		$freepgs $needpgs
+	exit 1
+fi
+
+#
+# Run the hugetlbfs test
+#
+./memfd_test hugetlbfs
+
+#
+# Give back any huge pages allocated for the test
+#
+if [ -n "$nr_hugepgs" ]; then
+	echo $nr_hugepgs > /proc/sys/vm/nr_hugepages
+fi
-- 
2.7.5

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