[PATCH] selftests/vm: Fix map_hugetlb length used for testing read and write

[Christophe Leroy]

Commit fa7b9a805c79 ("tools/selftest/vm: allow choosing mem size and
page size in map_hugetlb") added the possibility to change the size
of memory mapped for the test, but left the read and write test using
the default value. This is unnoticed when mapping a length greater
than the default one, but segfaults otherwise.

Fix read_bytes() and write_bytes() by giving them the real length.

Also fix the call to munmap().

Fixes: fa7b9a805c79 ("tools/selftest/vm: allow choosing mem size and page size 
in map_hugetlb")
Cc: sta...@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
 tools/testing/selftests/vm/map_hugetlb.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/vm/map_hugetlb.c 
b/tools/testing/selftests/vm/map_hugetlb.c
index 5a2d7b8efc40..6af951900aa3 100644
--- a/tools/testing/selftests/vm/map_hugetlb.c
+++ b/tools/testing/selftests/vm/map_hugetlb.c
@@ -45,20 +45,20 @@ 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 length)
 {
        unsigned long i;
 
-       for (i = 0; i < LENGTH; i++)
+       for (i = 0; i < length; i++)
                *(addr + i) = (char)i;
 }
 
-static int read_bytes(char *addr)
+static int read_bytes(char *addr, size_t length)
 {
        unsigned long i;
 
        check_bytes(addr);
-       for (i = 0; i < LENGTH; i++)
+       for (i = 0; i < length; i++)
                if (*(addr + i) != (char)i) {
                        printf("Mismatch at %lu\n", i);
                        return 1;
@@ -96,11 +96,11 @@ int main(int argc, char **argv)
 
        printf("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() length of MAP_HUGETLB memory must be hugepage aligned */
-       if (munmap(addr, LENGTH)) {
+       if (munmap(addr, length)) {
                perror("munmap");
                exit(1);
        }
-- 
2.25.0