selftests/vm: fix map_hugetlb length used for testing read and write

commit cabc30da10e677c67ab9a136b1478175734715c5 upstream.

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")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Leonardo Bras <leonardo@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/9a404a13c871c4bd0ba9ede68f69a1225180dd7e.1580978385.git.christophe.leroy@c-s.fr
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/testing/selftests/vm/map_hugetlb.c b/tools/testing/selftests/vm/map_hugetlb.c
index 5a2d7b8..6af9519 100644 (file)
--- 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);
        }