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

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Message-ID: <20240313170435.616724-41-sashal@kernel.org>
Date: Wed, 13 Mar 2024 13:04:34 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Christophe Leroy <christophe.leroy@....fr>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Leonardo Bras <leonardo@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Shuah Khan <shuah@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 40/41] selftests/vm: fix map_hugetlb length used for testing read and write

From: Christophe Leroy <christophe.leroy@....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@....fr>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Leonardo Bras <leonardo@...ux.ibm.com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Shuah Khan <shuah@...nel.org>
Cc: <stable@...r.kernel.org>
Link: http://lkml.kernel.org/r/9a404a13c871c4bd0ba9ede68f69a1225180dd7e.1580978385.git.christophe.leroy@c-s.fr
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.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