@@ -4,7 +4,11 @@
*
* Example of remapping huge page memory in a user application using the
* mremap system call. Code assumes a hugetlbfs filesystem is mounted
- * at './huge'. The code will use 10MB worth of huge pages.
+ * at './huge'. The amount of memory used by this test is decided by a command
+ * line argument in MBs. If missing, the default amount is 10MB.
+ *
+ * To make sure the test triggers pmd sharing and goes through the 'unshare'
+ * path in the mremap code use 1GB (1024) or more.
*/
#define _GNU_SOURCE
@@ -18,8 +22,10 @@
#include <linux/userfaultfd.h>
#include <sys/ioctl.h>
-#define LENGTH (1UL * 1024 * 1024 * 1024)
+#define DEFAULT_LENGTH_MB 10UL
+#define MB_TO_BYTES(x) (x * 1024 * 1024)
+#define FILE_NAME "huge/hugepagefile"
#define PROTECTION (PROT_READ | PROT_WRITE | PROT_EXEC)
#define FLAGS (MAP_SHARED | MAP_ANONYMOUS)
@@ -28,20 +34,20 @@ static void check_bytes(char *addr)
printf("First hex is %x\n", *((unsigned int *)addr));
}
-static void write_bytes(char *addr)
+static void write_bytes(char *addr, size_t len)
{
unsigned long i;
- for (i = 0; i < LENGTH; i++)
+ for (i = 0; i < len; i++)
*(addr + i) = (char)i;
}
-static int read_bytes(char *addr)
+static int read_bytes(char *addr, size_t len)
{
unsigned long i;
check_bytes(addr);
- for (i = 0; i < LENGTH; i++)
+ for (i = 0; i < len; i++)
if (*(addr + i) != (char)i) {
printf("Mismatch at %lu\n", i);
return 1;
@@ -99,11 +105,19 @@ static void register_region_with_uffd(ch
}
}
-int main(void)
+int main(int argc, char *argv[])
{
+ /* Read memory length as the first arg if valid, otherwise fallback to
+ * the default length. Any additional args are ignored.
+ */
+ size_t length = argc > 1 ? (size_t)atoi(argv[1]) : 0UL;
+
+ length = length > 0 ? length : DEFAULT_LENGTH_MB;
+ length = MB_TO_BYTES(length);
+
int ret = 0;
- int fd = open("/huge/test", O_CREAT | O_RDWR, 0755);
+ int fd = open(FILE_NAME, O_CREAT | O_RDWR, 0755);
if (fd < 0) {
perror("Open failed");
@@ -112,7 +126,7 @@ int main(void)
/* mmap to a PUD aligned address to hopefully trigger pmd sharing. */
unsigned long suggested_addr = 0x7eaa40000000;
- void *haddr = mmap((void *)suggested_addr, LENGTH, PROTECTION,
+ void *haddr = mmap((void *)suggested_addr, length, PROTECTION,
MAP_HUGETLB | MAP_SHARED | MAP_POPULATE, fd, 0);
printf("Map haddr: Returned address is %p\n", haddr);
if (haddr == MAP_FAILED) {
@@ -122,7 +136,7 @@ int main(void)
/* mmap again to a dummy address to hopefully trigger pmd sharing. */
suggested_addr = 0x7daa40000000;
- void *daddr = mmap((void *)suggested_addr, LENGTH, PROTECTION,
+ void *daddr = mmap((void *)suggested_addr, length, PROTECTION,
MAP_HUGETLB | MAP_SHARED | MAP_POPULATE, fd, 0);
printf("Map daddr: Returned address is %p\n", daddr);
if (daddr == MAP_FAILED) {
@@ -132,16 +146,16 @@ int main(void)
suggested_addr = 0x7faa40000000;
void *vaddr =
- mmap((void *)suggested_addr, LENGTH, PROTECTION, FLAGS, -1, 0);
+ mmap((void *)suggested_addr, length, PROTECTION, FLAGS, -1, 0);
printf("Map vaddr: Returned address is %p\n", vaddr);
if (vaddr == MAP_FAILED) {
perror("mmap2");
exit(1);
}
- register_region_with_uffd(haddr, LENGTH);
+ register_region_with_uffd(haddr, length);
- void *addr = mremap(haddr, LENGTH, LENGTH,
+ void *addr = mremap(haddr, length, length,
MREMAP_MAYMOVE | MREMAP_FIXED, vaddr);
if (addr == MAP_FAILED) {
perror("mremap");
@@ -150,10 +164,10 @@ int main(void)
printf("Mremap: Returned address is %p\n", addr);
check_bytes(addr);
- write_bytes(addr);
- ret = read_bytes(addr);
+ write_bytes(addr, length);
+ ret = read_bytes(addr, length);
- munmap(addr, LENGTH);
+ munmap(addr, length);
return ret;
}
@@ -111,7 +111,7 @@ fi
echo "-----------------------"
echo "running hugepage-mremap"
echo "-----------------------"
-./hugepage-mremap
+./hugepage-mremap 256
if [ $? -ne 0 ]; then
echo "[FAIL]"
exitcode=1