mm, selftests: test return value of munmap for MAP_HUGETLB memory

When MAP_HUGETLB memory is unmapped, the length must be hugepage aligned,
otherwise it fails with -EINVAL.

All tests currently behave correctly, but it's better to explcitly test
the return value for completeness and document the requirement, especially
if users copy map_hugetlb.c as a sample implementation.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joern Engel <joern@logfs.org>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Eric B Munson <emunson@akamai.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c b/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c
index 3d8e5b0..4900367 100644 (file)
--- a/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c
+++ b/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c
@@ -21,9 +21,13 @@ static int test_body(void)
                 * Typically the mmap will fail because no huge pages are
                 * allocated on the system. But if there are huge pages
                 * allocated the mmap will succeed. That's fine too, we just
-                * munmap here before continuing.
+                * munmap here before continuing.  munmap() length of
+                * MAP_HUGETLB memory must be hugepage aligned.
                 */
-               munmap(addr, SIZE);
+               if (munmap(addr, SIZE)) {
+                       perror("munmap");
+                       return 1;
+               }
        }
 
        p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,

diff --git a/tools/testing/selftests/vm/hugetlbfstest.c b/tools/testing/selftests/vm/hugetlbfstest.c
index ea40ff8..02e1072 100644 (file)
--- a/tools/testing/selftests/vm/hugetlbfstest.c
+++ b/tools/testing/selftests/vm/hugetlbfstest.c
@@ -34,6 +34,7 @@ static void do_mmap(int fd, int extra_flags, int unmap)
        int *p;
        int flags = MAP_PRIVATE | MAP_POPULATE | extra_flags;
        u64 before, after;
+       int ret;
 
        before = read_rss();
        p = mmap(NULL, length, PROT_READ | PROT_WRITE, flags, fd, 0);
@@ -44,7 +45,8 @@ static void do_mmap(int fd, int extra_flags, int unmap)
                        !"rss didn't grow as expected");
        if (!unmap)
                return;
-       munmap(p, length);
+       ret = munmap(p, length);
+       assert(!ret || !"munmap returned an unexpected error");
        after = read_rss();
        assert(llabs(after - before) < 0x40000 ||
                        !"rss didn't shrink as expected");

diff --git a/tools/testing/selftests/vm/map_hugetlb.c b/tools/testing/selftests/vm/map_hugetlb.c
index ac56639..addcd6f 100644 (file)
--- a/tools/testing/selftests/vm/map_hugetlb.c
+++ b/tools/testing/selftests/vm/map_hugetlb.c
@@ -73,7 +73,11 @@ int main(void)
        write_bytes(addr);
        ret = read_bytes(addr);
 
-       munmap(addr, LENGTH);
+       /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
+       if (munmap(addr, LENGTH)) {
+               perror("munmap");
+               exit(1);
+       }
 
        return ret;
 }