From: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> Subject: userfaultfd/selftests: create alias mappings in the shmem test Previously, we just allocated two shm areas: area_src and area_dst. With this commit, change this so we also allocate area_src_alias, and area_dst_alias. area_*_alias and area_* (respectively) point to the same underlying physical pages, but are different VMAs. In a future commit in this series, we'll leverage this setup to exercise minor fault handling support for shmem, just like we do in the hugetlb_shared test. Link: https://lkml.kernel.org/r/20210503180737.2487560-9-axelrasmussen@xxxxxxxxxx Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Brian Geffon <bgeffon@xxxxxxxxxx> Cc: "Dr . David Alan Gilbert" <dgilbert@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Jerome Glisse <jglisse@xxxxxxxxxx> Cc: Joe Perches <joe@xxxxxxxxxxx> Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> Cc: Lokesh Gidra <lokeshgidra@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Cc: Mina Almasry <almasrymina@xxxxxxxxxx> Cc: Oliver Upton <oupton@xxxxxxxxxx> Cc: Shaohua Li <shli@xxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Cc: Wang Qing <wangqing@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/vm/userfaultfd.c | 22 ++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) --- a/tools/testing/selftests/vm/userfaultfd.c~userfaultfd-selftests-create-alias-mappings-in-the-shmem-test +++ a/tools/testing/selftests/vm/userfaultfd.c @@ -278,13 +278,29 @@ static void shmem_release_pages(char *re static void shmem_allocate_area(void **alloc_area) { - unsigned long offset = - alloc_area == (void **)&area_src ? 0 : nr_pages * page_size; + void *area_alias = NULL; + bool is_src = alloc_area == (void **)&area_src; + unsigned long offset = is_src ? 0 : nr_pages * page_size; *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, offset); if (*alloc_area == MAP_FAILED) err("mmap of memfd failed"); + + area_alias = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE, + MAP_SHARED, shm_fd, offset); + if (area_alias == MAP_FAILED) + err("mmap of memfd alias failed"); + + if (is_src) + area_src_alias = area_alias; + else + area_dst_alias = area_alias; +} + +static void shmem_alias_mapping(__u64 *start, size_t len, unsigned long offset) +{ + *start = (unsigned long)area_dst_alias + offset; } struct uffd_test_ops { @@ -314,7 +330,7 @@ static struct uffd_test_ops shmem_uffd_t .expected_ioctls = SHMEM_EXPECTED_IOCTLS, .allocate_area = shmem_allocate_area, .release_pages = shmem_release_pages, - .alias_mapping = noop_alias_mapping, + .alias_mapping = shmem_alias_mapping, }; static struct uffd_test_ops hugetlb_uffd_test_ops = { _
