diff --git a/.gitignore b/.gitignore
index 53029e24..efc73a7c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -92,6 +92,7 @@
 /src/lstat64
 /src/makeextents
 /src/metaperf
+/src/mkswap
 /src/mmapcat
 /src/multi_open_unlink
 /src/nametest
@@ -111,6 +112,7 @@
 /src/seek_sanity_test
 /src/stale_handle
 /src/stat_test
+/src/swapon
 /src/t_access_root
 /src/t_dir_offset
 /src/t_dir_offset2
diff --git a/src/Makefile b/src/Makefile
index c42d3bb1..01fe99ef 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -26,7 +26,7 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \
 	renameat2 t_getcwd e4compact test-nextquota punch-alternating \
 	attr-list-by-handle-cursor-test listxattr dio-interleaved t_dir_type \
 	dio-invalidate-cache stat_test t_encrypted_d_revalidate \
-	attr_replace_test
+	attr_replace_test swapon mkswap
 
 SUBDIRS = log-writes perf
 
diff --git a/src/mkswap.c b/src/mkswap.c
new file mode 100644
index 00000000..d0bce2bd
--- /dev/null
+++ b/src/mkswap.c
@@ -0,0 +1,83 @@
+/* mkswap(8) without any sanity checks */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+struct swap_header {
+	char		bootbits[1024];
+	uint32_t	version;
+	uint32_t	last_page;
+	uint32_t	nr_badpages;
+	unsigned char	sws_uuid[16];
+	unsigned char	sws_volume[16];
+	uint32_t	padding[117];
+	uint32_t	badpages[1];
+};
+
+int main(int argc, char **argv)
+{
+	struct swap_header *hdr;
+	FILE *file;
+	struct stat st;
+	long page_size;
+	int ret;
+
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s PATH\n", argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	page_size = sysconf(_SC_PAGESIZE);
+	if (page_size == -1) {
+		perror("sysconf");
+		return EXIT_FAILURE;
+	}
+
+	hdr = calloc(1, page_size);
+	if (!hdr) {
+		perror("calloc");
+		return EXIT_FAILURE;
+	}
+
+	file = fopen(argv[1], "r+");
+	if (!file) {
+		perror("fopen");
+		free(hdr);
+		return EXIT_FAILURE;
+	}
+
+	ret = fstat(fileno(file), &st);
+	if (ret) {
+		perror("fstat");
+		free(hdr);
+		fclose(file);
+		return EXIT_FAILURE;
+	}
+
+	hdr->version = 1;
+	hdr->last_page = st.st_size / page_size - 1;
+	memset(&hdr->sws_uuid, 0x99, sizeof(hdr->sws_uuid));
+	memcpy((char *)hdr + page_size - 10, "SWAPSPACE2", 10);
+
+	if (fwrite(hdr, page_size, 1, file) != 1) {
+		perror("fwrite");
+		free(hdr);
+		fclose(file);
+		return EXIT_FAILURE;
+	}
+
+	if (fclose(file) == EOF) {
+		perror("fwrite");
+		free(hdr);
+		return EXIT_FAILURE;
+	}
+
+	free(hdr);
+
+	return EXIT_SUCCESS;
+}
diff --git a/src/swapon.c b/src/swapon.c
new file mode 100644
index 00000000..0cb7108a
--- /dev/null
+++ b/src/swapon.c
@@ -0,0 +1,24 @@
+/* swapon(8) without any sanity checks; simply calls swapon(2) directly. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/swap.h>
+
+int main(int argc, char **argv)
+{
+	int ret;
+
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s PATH\n", argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	ret = swapon(argv[1], 0);
+	if (ret) {
+		perror("swapon");
+		return EXIT_FAILURE;
+	}
+
+	return EXIT_SUCCESS;
+}
diff --git a/tests/generic/494 b/tests/generic/494
new file mode 100755
index 00000000..28468033
--- /dev/null
+++ b/tests/generic/494
@@ -0,0 +1,77 @@
+#! /bin/bash
+# FS QA Test 494
+#
+# Test invalid swap files.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2018 Facebook.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+_supported_fs generic
+_supported_os Linux
+_require_scratch_swapfile
+_require_test_program mkswap
+_require_test_program swapon
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+echo "File with holes"
+# We can't use _format_swapfile because we're using our custom mkswap and
+# swapon.
+touch "$SCRATCH_MNT/swap"
+$CHATTR_PROG +C "$SCRATCH_MNT/swap" > /dev/null 2>&1
+chmod 0600 "$SCRATCH_MNT/swap"
+$XFS_IO_PROG -c "truncate $(($(get_page_size) * 10))" "$SCRATCH_MNT/swap"
+"$here/src/mkswap" "$SCRATCH_MNT/swap"
+"$here/src/swapon" "$SCRATCH_MNT/swap"
+swapoff "$SCRATCH_MNT/swap" > /dev/null 2>&1
+
+echo "Empty swap file (only swap header)"
+rm -f "$SCRATCH_MNT/swap"
+touch "$SCRATCH_MNT/swap"
+$CHATTR_PROG +C "$SCRATCH_MNT/swap" > /dev/null 2>&1
+chmod 0600 "$SCRATCH_MNT/swap"
+_pwrite_byte 0x61 0 $(get_page_size) "$SCRATCH_MNT/swap" >> $seqres.full
+"$here/src/mkswap" "$SCRATCH_MNT/swap"
+"$here/src/swapon" "$SCRATCH_MNT/swap"
+swapoff "$SCRATCH_MNT/swap" > /dev/null 2>&1
+
+status=0
+exit
diff --git a/tests/generic/494.out b/tests/generic/494.out
new file mode 100644
index 00000000..bd452bb2
--- /dev/null
+++ b/tests/generic/494.out
@@ -0,0 +1,5 @@
+QA output created by 494
+File with holes
+swapon: Invalid argument
+Empty swap file (only swap header)
+swapon: Invalid argument
diff --git a/tests/generic/group b/tests/generic/group
index 9778930a..10267414 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -496,3 +496,4 @@
 491 auto quick freeze mount
 492 auto quick swap
 493 auto quick swap
+494 auto quick swap
