| Message ID | 20210413051721.2896915-7-axelrasmussen@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | userfaultfd: add minor fault handling for shmem | expand |
On Mon, Apr 12, 2021 at 10:17:18PM -0700, Axel Rasmussen wrote: > 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; > +} It would be nice if shmem_allocate_area() could merge with hugetlb_allocate_area() somehow, but not that urgent. Reviewed-by: Peter Xu <peterx@redhat.com>
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index fc40831f818f..1f65c4ab7994 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -278,13 +278,29 @@ static void shmem_release_pages(char *rel_area) 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_test_ops = { .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 = {
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. Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> --- tools/testing/selftests/vm/userfaultfd.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-)