userfaultfd/selftests: clean up hugetlb allocation code

The message for commit 146de078b7bc ("userfaultfd/selftests: fix hugetlb
area allocations") says there is no need to create a hugetlb file in the
non-shared testing case.  However, the commit did not actually change
the code to prevent creation of the file.

While it is technically true that there is no need to create and use a
hugetlb file in the case of non-shared-testing, it is useful.  This is
because 'hole punching' of a hugetlb file has the potentially incorrect
side effect of also removing pages from private mappings.  The
userfaultfd test relies on this side effect for removing pages from the
destination buffer during rounds of stress testing.

Remove the incomplete code that was added to deal with no hugetlb file.
Just keep the code that prevents reserves from being created for the
destination area.

Link: https://lkml.kernel.org/r/20220104021729.111006-1-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index c9eddd25ba1776d9983378ff054fac5e71852d83..d3fd24f9fae8c89579454d6eefacf59ccbb94cb3 100644 (file)
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -87,7 +87,7 @@ static bool test_uffdio_minor = false;
 
 static bool map_shared;
 static int shm_fd;
-static int huge_fd = -1;       /* only used for hugetlb_shared test */
+static int huge_fd;
 static char *huge_fd_off0;
 static unsigned long long *count_verify;
 static int uffd = -1;
@@ -223,9 +223,6 @@ static void noop_alias_mapping(__u64 *start, size_t len, unsigned long offset)
 
 static void hugetlb_release_pages(char *rel_area)
 {
-       if (huge_fd == -1)
-               return;
-
        if (fallocate(huge_fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                      rel_area == huge_fd_off0 ? 0 : nr_pages * page_size,
                      nr_pages * page_size))
@@ -238,17 +235,17 @@ static void hugetlb_allocate_area(void **alloc_area)
        char **alloc_area_alias;
 
        *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
-                          map_shared ? MAP_SHARED :
-                          MAP_PRIVATE | MAP_HUGETLB |
+                          (map_shared ? MAP_SHARED : MAP_PRIVATE) |
+                          MAP_HUGETLB |
                           (*alloc_area == area_src ? 0 : MAP_NORESERVE),
-                          huge_fd,
-                          *alloc_area == area_src ? 0 : nr_pages * page_size);
+                          huge_fd, *alloc_area == area_src ? 0 :
+                          nr_pages * page_size);
        if (*alloc_area == MAP_FAILED)
                err("mmap of hugetlbfs file failed");
 
        if (map_shared) {
                area_alias = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
-                                 MAP_SHARED,
+                                 MAP_SHARED | MAP_HUGETLB,
                                  huge_fd, *alloc_area == area_src ? 0 :
                                  nr_pages * page_size);
                if (area_alias == MAP_FAILED)