[PATCH 4.19 40/41] selftests/vm: fix map_hugetlb length used for testing read and write

Sasha Levin
2024-03-13T17:05:23Z

From: Christophe Leroy <christophe.leroy@c-s.fr>

[ Upstream commit cabc30da10e677c67ab9a136b1478175734715c5 ]

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: Sasha Levin <sashal@kernel.org>
---
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 7b41cc6ecb0bf..c65c55b7a789f 100644
--- a/tools/testing/selftests/vm/map_hugetlb.c
+++ b/tools/testing/selftests/vm/map_hugetlb.c
@@ -46,20 +46,20 @@ 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;
@@ -103,11 +103,11 @@ 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);
}
--
2.43.0