linux-kernel - [PATCH 4.19 26/41] selftests: mm: fix map_hugetlb failure on 64K page size systems

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Date: Wed, 13 Mar 2024 13:04:20 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Nico Pache <npache@...hat.com>,
	Donet Tom <donettom@...ux.vnet.ibm.com>,
	Shuah Khan <shuah@...nel.org>,
	Christophe Leroy <christophe.leroy@....fr>,
	Michael Ellerman <mpe@...erman.id.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 26/41] selftests: mm: fix map_hugetlb failure on 64K page size systems

From: Nico Pache <npache@...hat.com>

[ Upstream commit 91b80cc5b39f00399e8e2d17527cad2c7fa535e2 ]

On systems with 64k page size and 512M huge page sizes, the allocation and
test succeeds but errors out at the munmap.  As the comment states, munmap
will failure if its not HUGEPAGE aligned.  This is due to the length of
the mapping being 1/2 the size of the hugepage causing the munmap to not
be hugepage aligned.  Fix this by making the mapping length the full
hugepage if the hugepage is larger than the length of the mapping.

Link: https://lkml.kernel.org/r/20240119131429.172448-1-npache@redhat.com
Signed-off-by: Nico Pache <npache@...hat.com>
Cc: Donet Tom <donettom@...ux.vnet.ibm.com>
Cc: Shuah Khan <shuah@...nel.org>
Cc: Christophe Leroy <christophe.leroy@....fr>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/testing/selftests/vm/map_hugetlb.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/vm/map_hugetlb.c b/tools/testing/selftests/vm/map_hugetlb.c
index 5a2d7b8efc407..ab349c6db00d4 100644
--- a/tools/testing/selftests/vm/map_hugetlb.c
+++ b/tools/testing/selftests/vm/map_hugetlb.c
@@ -15,6 +15,7 @@
 #include <unistd.h>
 #include <sys/mman.h>
 #include <fcntl.h>
+#include "vm_util.h"
 
 #define LENGTH (256UL*1024*1024)
 #define PROTECTION (PROT_READ | PROT_WRITE)
@@ -70,10 +71,16 @@ int main(int argc, char **argv)
 {
 	void *addr;
 	int ret;
+	size_t hugepage_size;
 	size_t length = LENGTH;
 	int flags = FLAGS;
 	int shift = 0;
 
+	hugepage_size = default_huge_page_size();
+	/* munmap with fail if the length is not page aligned */
+	if (hugepage_size > length)
+		length = hugepage_size;
+
 	if (argc > 1)
 		length = atol(argv[1]) << 20;
 	if (argc > 2) {
-- 
2.43.0