linux-kernel - [PATCH AUTOSEL 4.14 7/7] selftests/memfd: clean up mapping in mfd_fail

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Date:   Tue,  1 Mar 2022 15:21:28 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Shuah Khan <shuah@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>, gthelen@...gle.com,
        linux-kselftest@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 7/7] selftests/memfd: clean up mapping in mfd_fail_write

From: Mike Kravetz <mike.kravetz@...cle.com>

[ Upstream commit fda153c89af344d21df281009a9d046cf587ea0f ]

Running the memfd script ./run_hugetlbfs_test.sh will often end in error
as follows:

    memfd-hugetlb: CREATE
    memfd-hugetlb: BASIC
    memfd-hugetlb: SEAL-WRITE
    memfd-hugetlb: SEAL-FUTURE-WRITE
    memfd-hugetlb: SEAL-SHRINK
    fallocate(ALLOC) failed: No space left on device
    ./run_hugetlbfs_test.sh: line 60: 166855 Aborted                 (core dumped) ./memfd_test hugetlbfs
    opening: ./mnt/memfd
    fuse: DONE

If no hugetlb pages have been preallocated, run_hugetlbfs_test.sh will
allocate 'just enough' pages to run the test.  In the SEAL-FUTURE-WRITE
test the mfd_fail_write routine maps the file, but does not unmap.  As a
result, two hugetlb pages remain reserved for the mapping.  When the
fallocate call in the SEAL-SHRINK test attempts allocate all hugetlb
pages, it is short by the two reserved pages.

Fix by making sure to unmap in mfd_fail_write.

Link: https://lkml.kernel.org/r/20220219004340.56478-1-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
Cc: Joel Fernandes <joel@...lfernandes.org>
Cc: Shuah Khan <shuah@...nel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/testing/selftests/memfd/memfd_test.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index 845e5f67b6f02..cf4c5276eb06a 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -416,6 +416,7 @@ static void mfd_fail_write(int fd)
 			printf("mmap()+mprotect() didn't fail as expected\n");
 			abort();
 		}
+		munmap(p, mfd_def_size);
 	}
 
 	/* verify PUNCH_HOLE fails */
-- 
2.34.1