diff mbox series

mm, hugepages: make memory size variable in hugepage-mremap selftest

Message ID 20211124203805.3700355-1-yosryahmed@google.com
State Accepted
Commit f77a286de48c04f7dd248b41584645afc3613bb1
Headers show
Series mm, hugepages: make memory size variable in hugepage-mremap selftest | expand

Commit Message

Yosry Ahmed Nov. 24, 2021, 8:38 p.m. UTC
The hugetlb vma mremap() test currently maps 1GB of memory to trigger
pmd sharing and make sure that 'unshare' path in mremap code works.
The test originally only mapped 10MB of memory (as specified by the
header comment) but was later modified to 1GB to tackle this case.

However, not all machines will have 1GB of memory to spare for this
test. Adding a mapping size arg will allow run_vmtest.sh to pass an
adequate mapping size, while allowing users to run the test
independently with arbitrary size mappings.

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
---

This is a replacement for
mm-hugepages-fix-size-in-hugetlb-mremap-test.patch in -mm tree.

The original patch set the amount of memory used by the test to 10MB
instead of 1GB to avoid running out of memory. However, the test must
map 1GB or more to trigger pmd sharing. Hence, a variable mapping size
is the best solution here to allow for both options.

---
 tools/testing/selftests/vm/hugepage-mremap.c | 46 +++++++++++++-------
 tools/testing/selftests/vm/run_vmtests.sh    |  2 +-
 2 files changed, 31 insertions(+), 17 deletions(-)
diff mbox series

Patch

diff --git a/tools/testing/selftests/vm/hugepage-mremap.c b/tools/testing/selftests/vm/hugepage-mremap.c
index 257df94697a5..2a7c33631a29 100644
--- a/tools/testing/selftests/vm/hugepage-mremap.c
+++ b/tools/testing/selftests/vm/hugepage-mremap.c
@@ -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(char *addr, size_t len)
 	}
 }
 
-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;
 }
diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
index a24d30af3094..75d401741394 100755
--- a/tools/testing/selftests/vm/run_vmtests.sh
+++ b/tools/testing/selftests/vm/run_vmtests.sh
@@ -111,7 +111,7 @@  fi
 echo "-----------------------"
 echo "running hugepage-mremap"
 echo "-----------------------"
-./hugepage-mremap
+./hugepage-mremap 256
 if [ $? -ne 0 ]; then
 	echo "[FAIL]"
 	exitcode=1